Applied Colloids Surfactants

Insektenvernichtungsmittel künftig ein zunehmendes Problem für Gewässer in Europa - Helmholtz-Zentrum für Umweltforschung UFZ - Forschen für die Umwelt

2012-01-27T09:27:00.001+01:00

Insektenvernichtungsmittel künftig ein zunehmendes Problem für Gewässer in Europa - Helmholtz-Zentrum für Umweltforschung UFZ - Forschen für die Umwelt

Zitate:
Europas Gewässer werden in Zukunft stärker mit Insektenvernichtungsmitteln belastet sein als bisher. Das ist das Ergebnis einer Studie des Helmholtz-Zentrums für Umweltforschung (UFZ)...

Die Wissenschaftler empfehlen deshalb, den Eintrag von Pflanzenschutzmitteln drastisch zu minimieren. Neben einer Verminderung des Pestizideinsatzes kann dies durch die Einrichtung von Pufferzonen am Gewässer erfolgen.

Lediglich für 12 Küstenstaaten der USA gibt es Schätzungen, die einen generellen Anstieg des Insektizideinsatzes im Zeitraum 2000 bis 2100 von bis zu 28 Prozent erwarten. Die europäische Studie dagegen rechnet mit einem wesentlichen höheren Anstieg von bis zum 23fachen des momentanen Insektizideinsatzes in einzelnen Ländern je nach Stärke des Temperaturanstiegs und der zugrunde gelegten Landnutzungsänderung.

Außer Begrenzung der Auswirkungen durch Pufferzonen werden keine Alternativen gefordert/diskutiert.

Eine Alternative wäre Stärkung der natürlichen Feinde der Schadinsekten.

Diethylhexyl phthalate (DEHP), bisphenol A, and pesticides Pollute European Water Bodies More Than Previously Thought

2011-11-17T12:26:00.001+01:00

Diethylhexyl phthalate (DEHP), bisphenol A, and pesticides Pollute European Water Bodies More Than Previously Thought

Studie: Pestizide belasten Gewässer stärker als gedacht

SOURCE: Helmholtz Association of German Research Centres

.....
One of the most frequently registered compounds was diethylhexyl phthalate (DEHP), a chemically-produced softener which may impair fertility and is therefore banned in the EU from 2015. This is followed by another softener bisphenol A (BPA), which may also impair fertility, and diclofenac and ibuprofen, two pharmaceutical substances used commonly in painkillers.
The scientists classified a total of 73 compounds as potential priority pollutants. Around two thirds of these are pesticides, i.e. products used in agriculture to protect crops against disease, pests and weeds.
....
"Terbuthylazine is a compound that is structurally closely related to the priority pollutants simazine and atrazine, which may not be applied any more. This is a nice example how small structural modifications of chemical products may apparently improve the chemical status without mitigating any hazards to the aquatic ecosystems."
....We were also surprised that substances previously classified as harmless, such as HHCB, which is used as a synthetic musk fragrance in personal care products, are present in the environment in alarming concentrations,"

less than five cents per person per day to provide clean drinking water

2011-08-23T11:56:00.000+02:00

'Research confirmed cost of just pennies a day per person to provide safe drinking water; Independent, scientific research validates potable water solution and its impact in a developing country; Project Safewater-Colón findings can help address the United Nation's Millennium Development Goals'
Article on water.online

see http://www.projectsafewater.com/

Wir.Dienen.Deutschland?

2011-07-06T08:18:00.002+02:00

für Frieden und Demokratie in der Welt.

wie unsere Regierung mit Waffenlieferungen an Saudiarabien.

Saudiarabien ist unser Verbündeter

wie vormals Gaddafi.

Militär dient der Fortsetzung der Politik mit anderen Mitteln.

Dem dienen?

Wir.Dienen.Deutschland.

2011-07-05T08:19:00.002+02:00

Wir.Dienen.Deutschland.

für den Frieden der Welt.

Da können dann auch mal paar kleine Afghanen drauf gehen.

'Deutschland muß auch seine wirtschaftlichen Interessen militärisch verteidigen'

Heil Dir im Siegerkranz fürs deutsche Vaterland sterben wir.

Alternative

Triclosan replacement

2011-03-29T11:25:00.003+02:00

sensidin^® DO – a triclosan alternative for deodorants

Product offered by

Schülke&Mayr GmbH

Product description
sensidin® DO combines the well-known deodorant and skin care
properties of ethylhexylglycerin with the antimicrobial properties
of octenidine HCl.

see also industry urged to take precautions with triclosan

Industry urged to take precautions with triclosan

2010-12-07T09:00:00.002+01:00

source cosmetics design-europe.com

By Andrew McDougall, 03-Dec-2010

Following various studies on the use of the antibacterial agent triclosan in consumer products, including oral care, experts are urging companies to remove it from their formulations as a precaution.

Elizabeth Salter Green, director of ChemTrust, a health and environmental body, explained that on a precautionary basis the chemical may not be safe to use at any level.

“It is important to stress that triclosan is not a dioxin, however concerns are that under certain circumstances it can develop the ability to disrupt hormones,” she told CosmeticsDesign-Europe.com.

Found in many consumer products

Triclosan is an ingredient added to many consumer products as an antibacterial ingredient.

It may be found in products such as antibacterial soaps and body washes, toothpastes, and some cosmetics. It is regulated by the U.S. Food and Drug Administration (FDA), and the European Union.

At this time, the FDA does not have evidence that triclosan added to antibacterial soaps and body washes provides extra health benefits over soap and water. However it stated that in 1997, reviewed extensive effectiveness data on triclosan in Colgate Total toothpaste showing that triclosan in this product was effective in preventing gingivitis.

Salter Green suggested that whilst one toxin may be harmless in a product individually, they may be dangerous if reacting together, suggesting that if there was no benefit for the toxin, it should be left out of the formulation.

Removed from GSK’s oral products

Oral care giant, GlaxoSmithKline, has removed triclosan from its Aquafresh and Sensodyne toothpastes, as well as its Corsodyl mouthwash, according to the University of Florida which has performed a study on the ingredient in sheep.

“If one eats the right foods and maintains correct dental hygiene, then triclosan, or other antibacterial agents are not needed,” explained Salter Green.

In the study by the University of Florida, researchers found that levels of triclosan were potentially damaging to the unborn foetus, if ingested by the carrying mother.

“We know it's a problem. But we just don't know how much of a problem. Triclosan can affect blood flow to the uterus, meaning the baby’s brain does not get the oxygen it needs,” said Professor Margaret James, who is the lead-author of the present study.

Discussing this particular study, Salter Green mentioned that a developing foetus in the uterus is extremely sensitive, and may be affected by disrupted hormone affecting brain development, metabolism, or the reproductive system.

Although this test was carried out on sheep, she explained that if the triclosan disrupts the hormone activity in an animal, whilst not being 100 per cent comparable, preserved hormonal evolution would suggest possible dangers to humans, and that the agent should be avoided if possible purely from a precautionary level.

comment

after wide spread use in sanitizers an increase in dioxine levels was experienced, leading to the conclusion that under some circumstances dioxines may be formed from triclosan.

FDA-fact sheet triclosan

What is triclosan?

Triclosan is an ingredient added to many consumer products to reduce or prevent bacterial contamination. It may be found in products such as clothing, kitchenware, furniture, and toys. It also may be added to antibacterial soaps and body washes, toothpastes, and some cosmetics—products regulated by the U.S. Food and Drug Administration (FDA).

What is known about the safety of triclosan?

Triclosan is not currently known to be hazardous to humans. But several scientific studies have come out since the last time FDA reviewed this ingredient that merit further review.

Animal studies have shown that triclosan alters hormone regulation. However, data showing effects in animals don’t always predict effects in humans. Other studies in bacteria have raised the possibility that triclosan contributes to making bacteria resistant to antibiotics.

In light of these studies, FDA is engaged in an ongoing scientific and regulatory review of this ingredient. FDA does not have sufficient safety evidence to recommend changing consumer use of products that contain triclosan at this time.

Does triclosan provide a benefit in consumer products?

For some consumer products, there is clear evidence that triclosan provides a benefit. In 1997, FDA reviewed extensive effectiveness data on triclosan in Colgate Total toothpaste. The evidence showed that triclosan in this product was effective in preventing gingivitis.

For other consumer products, FDA has not received evidence that the triclosan provides an extra benefit to health. At this time, the agency does not have evidence that triclosan in antibacterial soaps and body washes provides any benefit over washing with regular soap and water.

What consumers should know:

Triclosan is not known to be hazardous to humans.
FDA does not have sufficient safety evidence to recommend changing consumer use of products that contain triclosan at this time.
In light of questions raised by recent animal studies of triclosan, FDA is reviewing all of the available evidence on this ingredient’s safety in consumer products. FDA will communicate the findings of its review to the public in spring 2011.
At this time, FDA does not have evidence that triclosan added to antibacterial soaps and body washes provides extra health benefits over soap and water. Consumers concerned about using hand and body soaps with triclosan should wash with regular soap and water.
Consumers can check product labels to find out whether products contain triclosan.

How can I tell if there is triclosan in a product that I am using?

Antibacterial soaps and body washes, and toothpastes are considered over-the-counter drugs. If an over-the-counter drug contains triclosan, it will be listed as an ingredient on the label, in the Drug Facts box. If a cosmetic contains triclosan, it will be included in the ingredient list on the product label.

What is FDA doing to evaluate the safety of triclosan?

We are engaged in an ongoing scientific and regulatory review of the safety of triclosan in FDA-regulated products. We also have partnered with other Federal Agencies to study the effects of this substance on animal and environmental health (see http://www.epa.gov/oppsrrd1/REDs/factsheets/triclosan_fs.htm; http://www.epa.gov/endo/).

FDA is working to incorporate the most up-to-date data and information into the regulations that govern the use of triclosan in consumer products. FDA will communicate the findings of its review to the public in spring 2011.

This article appears on FDA's Consumer Updates page, which features the latest on all FDA-regulated products.

Date Posted: April 8, 2010

new interest in surfactant enhanced soil clean-up

2010-12-03T11:25:00.002+01:00

In the last years I only sporadically observed new abstracts on this topic.
In the latest issue of clu-in.org I found several of them. It seems interest in this topic is revitalizing.

the first is not associated with surfactants I think

ADVANCED METHODOLOGIES FOR THE TREATMENT OF HYDROCARBON CONTAMINATED SLUDGES FROM SOIL WASHING PROCESSES

Garcia Frutos, F.J., O. Escolano, R. Perez, A. Rubio, A. Gimeno, M.D. Fernandez, M. Babin, G. Carbonell, C. Perucha, and J. Laguna. First Spanish National Conference on Advances in Materials Recycling and Eco-Energy, Madrid, 12-13 November 2009. Paper S02-6, p 49-52, 2009

Fine products (silt-clay fractions) in sludge from soil washing plants following bulk soil treatment usually are highly contaminated. These fractions commonly are committed to landfill disposal or thermal destruction (in the case of organic contaminants). This paper presents the results of preliminary physical-chemical and bioremediation treatability tests carried out on a hydrocarbon-heavy sludge sample after bulk soil processing in a soil washing plant. To date, best results were obtained in two bioremediation processes tested at lab scale—landfarming and bioreactors—which decreased hydrocarbon levels by better than 50% in two months and one month, respectively. http://digital.csic.es/bitstream/10261/18607/1/S02_6.pdf

comment: reducing the very high contamination with spending time and money by only 50 % is really not worse the effort.

ULTRASOUND ASSISTED SOIL WASHING FOR REMOVAL OF DIESEL WITH SURFACTANT

Cho, S.-H., Y. Son, J. Cha, S.-G. Nam, M. Lim, and J. Khim, Korea Univ.
Proceedings of Symposium on Ultrasonic Electronics, Vol 30, p 147-148, 2009 [18-20 November 2009, Paper 1P4-31]

Mechanical mixing generally is a key process in conventional soil washing, sometimes accompanied by injection of anionic or non-ionic surfactants to enhance mass transfer of pollutants from soil to aqueous phase. Tests of the application of ultrasound to the washing process indicate a significant increase in removal efficiency. When the washing water or slurry was irradiated with ultrasound, cavitation events occurred, and sonochemical and sonophysical effects were induced. Sonophysical effects, such as micro jet and micro streaming, could enhance mass transfer of organic/inorganic pollutants from soil phase to aqueous phase. This paper describes the conduct and results of a study undertaken to compare an ultrasonic soil washing process with a conventional mechanical soil washing treatment to gain a better understanding of the mechanisms of each process. http://www.use-jp.org/USE2010/proceedings/USE09/pdf/1P4-31.pdf

TREATMENT OF FUEL-OIL CONTAMINATED SOILS BY BIODEGRADABLE SURFACTANT WASHING FOLLOWED BY FENTON-LIKE OXIDATION

Tsai, T.T. and C.M. Kao (National Sun Yat-Sen Univ., Taiwan); R.Y. Surampalli (U.S. EPA, Kansas City, KS); S. H. Liang (National Sun Yat-Sen Univ.).
Journal of Environmental Engineering, Vol 135 No 10, p 1015-1024, 2009

A bench-scale study was conducted to develop a two-stage remedial system consisting of surfactant washing followed by a Fenton-like oxidation process to remediate fuel-oil contaminated soils. The researchers also evaluated the effects of residual surfactant and soil organic matter (SOM) on the efficiency of Fenton-like oxidation; the effect of potassium dihydrogen phosphate (KH₂PO₄) addition on the stability of H₂O₂ and oxidation efficiency; and the possible oxidation products after the oxidation process. In the surfactant washing stage, a biodegradable surfactant, Simple Green (SG) at 50 g/L, was applied to flush fuel-oil contaminated soil having initial total petroleum hydrocarbons (TPHs) concentration of 50,000 mg/kg. Washing with 45 pore volumes (PVs) of SG followed by 25 PVs of deionized water achieved 90% TPH removal, dropping the soil TPH concentration from 50,000 to 4,950 mg/kg. In the Fenton-like oxidation stage at initial soil TPH concentration of ~4,950 mg/kg, TPH removal efficiency increased significantly with increased H₂O₂ concentrations. There was evidence that residual SG and SOM can compete with TPH for oxidants and thereby decrease oxidation efficiency; hence, an oxidation-sorption-desorption-oxidation scheme for soil TPH was observed in this experiment due to the initial sorption of TPH on SOM. Addition of 2.2 mM of KH₂PO₄ increased the stability and half-life of H₂O₂ but decreased TPH removal efficiency. The oxidation potential of the Fenton-like process was insufficient to oxidize fuel oil completely to nontoxic end products. The by-products observed after the oxidation process contained carboxyl groups with molecular weights similar to their parent compounds. Results indicate that the two-stage remedial system shows promise for future treatment of fuel-oil contaminated soil.

REMEDIATION OF DDT-CONTAMINATED SOIL USING OPTIMIZED MIXTURES OF SURFACTANTS AND A MIXING SYSTEM
Ghazali, M., E. McBean, H. Shen, W. Anderson, and P.-A. Dastous.
Remediation Journal, Vol 20 No 4, p 119-132, 2010

A surfactant-aided soil washing technique was studied as an alternative method for remediation of DDT-contaminated clayey soil. The ex situ process used both nonionic and anionic surfactants. A mixture of 1% nonionic surfactant (Brij 35) and 1% anionic surfactant (SDBS) removed more than 50% of DDT from soil in a flow-through system, whereas individual surfactants or other combinations of the surfactants exhibited lower removal efficiency. The use of a mixing system improved the soil washing process. A combination of 2% Brij 35 and 0.1% SDBS was found to be optimum, removing 70 to 80% of DDT. Prewashing the soil with tap water decreased the adsorption of surfactants to soil particles by 30 to 40%, and postwashing recovered 90% of the surfactants.

BENCH SCALE TREATABILITY STUDIES OF CONTAMINATED SOIL USING SOIL WASHING TECHNIQUE

Gupta, M.K., R.K. Srivastava, and A.K. Singh.
E-Journal of Chemistry, Vol 7 No 1, p 73-80, 2010

Surfactant washing is an ex situ process. The excavated contaminated soil can be heaped on plastic liners or other impermeable barriers and irrigated with washing solutions such as surfactant; alternatively, batch washing of the contaminated soil can be conducted in tanks or lined pits using continuous flows washing in countercurrent or normal modes. The authors applied soil washing using plain water enhanced with surfactants to a study of the remediation of soil contaminated with engine lubricant oil or a heavy metal. The engine oil was used at different percentages (by dry weight of the soil) to contaminate the soil artificially. The geotechnical properties of the soil underwent large modifications after mixing with the oil. Sorption experiments were conducted with cadmium metal in an aqueous medium at different initial concentrations of the metal and at varying pH values of the sorbing medium. For the remediation of contaminated soil matrices, a nonionic surfactant was used for the restoration of geotechnical properties of the soil samples contaminated with lubricant oil, while an anionic surfactant was employed to desorb cadmium from the contaminated soil matrix. The surfactant for soil contaminated with lubricant oil was able to restore properties up to 98% of those of virgin soil, while up to 54% cadmium was desorbed from the contaminated soil matrix in surfactant-aided desorption experiments. http://www.e-journals.in/PDF/V7N1/73-80.pdf

comment: As nonionic surfactant Triton X-100, as anionic Sodium Dodecyl Sulfate, selection seems to be based on scholarly aspects.
In my experience for mineral oil contaminated soil a mixture of anionic/nonionic works best, e.g. 3 parts Na Alkyl benzene sulfonate / 7 parts Synperonic 91/4

ELECTROKINETIC REMOVAL OF PETROLEUM HYDROCARBON FROM RESIDUAL CLAYEY SOIL FOLLOWING A WASHING PROCESS
Jeon, C.-S., J.-S. Yang, K.-J. Kim, and K. Baek.
CLEAN — Soil, Air, Water, Vol 38 No 2, Feb 2010

A study was conducted of total petroleum hydrocarbon (TPH) removal from residual clayey soil using an electrokinetic process following a washing procedure. Eight electrokinetic experiments were carried out to investigate the characteristics of TPH removal. When 0.1 M MgSO₄ or 0.1 M NaOH was used as an electrolyte, the electric current increased rapidly within the first 100 or 200 h, respectively. A negatively charged soil surface resulted in a more negative zeta potential and greater electroosmotic flow toward the cathode. The accumulated electroosmotic flow was higher when using 0.1 M NaOH as the anolyte-purging solution than when using 0.1 M MgSO₄. Although the energy consumption for the two purging solutions was similar, the efficiencies of TPH removal when 0.1 M MgSO₄ and 0.1 M NaOH with surfactant were used were 0 and 39, respectively, because the electroosmotic flow rate increased with TPH removal efficiency. When 5 isopropyl alcohol was used as a circulation solution, the electric current increased, but the TPH removal was similar to that using water. In terms of energy consumption, the use of a surfactant-enhanced electrokinetic process with NaOH as electrolyte was effective in removing TPHs from low-permeability soil. http://onlinelibrary.wiley.com/doi/10.1002/clen.200900190/pdf

REMOVAL OF HIGH CONCENTRATIONS OF POLYCYCLIC AROMATIC HYDROCARBONS FROM CONTAMINATED SOIL BY BIODIESEL
Jinbao Wu, Zongqiang Gong, Liyan Zheng, Yanli Yi, Jinghua Jin, Xiaojun Li and Peijun Li
Frontiers of Environmental Science & Engineering in China, [online prior to print publication] 2010
Solubilizing experiments were carried out to evaluate the ability of biodiesel to remove PAHs from highly contaminated manufactured gas plant (MGP) and PAH-spiked soils alongside applications of hydroxypropyl-beta-cyclodextrin (HPCD) and tween 80 as comparisons. Biodiesel displayed the highest solubilities for phenanthrene (420.7 mg/L), pyrene (541.0 mg/L), and benzo(a)pyrene (436.3 mg/L). These corresponded to several-fold increases relative to 10% HPCD and tween 80. Biodiesel showed a good efficiency for PAH removal from the spiked and MGP soils for both low- and high-molecular-weight PAHs at high concentrations. Biodiesel was a more effective agent for PAH removal from the spiked soils compared with HPCD and tween 80; it achieved over 77.9% removal of individual PAHs. Tween 80 also showed comparable capability with biodiesel for PAH solubilization at a concentration of 10% for the spiked soils. Biodiesel solubilized a wider range of PAHs than HPCD and tween 80 for the MPG soils. At PAH concentrations of 229.6 and 996.9 mg/kg, biodiesel removed >80% of total PAHs. The investigators observed a significant difference between PAH removals from the spiked and field MGP soils: PAH removals from the MGP soil by HPCD and tween 80 were much lower than those from the spiked soil. These results demonstrate the potential for utilizing biodiesel for remediation of highly PAH-contaminated soil.

comment: Though biodiesel worked best (I experienced the same), it works when used as 100 %. Clean-up of biodiesel for recycling proved difficult, with activated carbon it will be costly. For PAH extraction I would suggest a combination of about 1 part carboxymethyl cellulose / 9 Part Synperonic 91/4.

WASHING OF FIELD WEATHERED CRUDE OIL CONTAMINATED SOIL WITH AN ENVIRONMENTALLY COMPATIBLE SURFACTANT, ALKYL POLYGLUCOSIDE
Han, M., G. Ji, and J. Ni, Peking Univ., Beijing, China.
Chemosphere, Vol 76 No 5, p 579-86, 2009
Weathered crude oil-contaminated soils are much more difficult to remediate than those freshly contaminated. Although surfactant-enhanced ex situ soil washing can be used to remediate the weathered soils, surfactant toxicity is a major concern. A class of green surfactants, alkyl polyglucosides (APGs), was tested for washing field-weathered soils with relatively high oil concentration (123 mg/g dry soil) from an oilfield in China. APG1214, characterized with a longer alkyl chain, was more effective than APG0810 for removing crude oil. Addition of inorganic sodium salts to the APG1214 solution further improved crude oil removal efficiency. Washing parameters (temperature, washing time, agitation speed, and solution/soil ratio) were investigated, further optimized, and integrated with an orthogonal design. Under optimum conditions, removal efficiency reached 97%. GC/MS analysis showed that the proportion of small n-alkanes (C(16) to C(23)) in residual crude oil gradually increased, which helped to interpret the oil removal mechanism. Removal of large n-alkanes was achieved from the synergy between APG1214 and inorganic salts, which was the opposite of the effect when they were added separately. This study presents a promising technique for remediation of weathered crude oil-contaminated soils with ecologically compatible surfactant and provides guidelines for its practical application.

Asphaltene stability - nonscanning NIR technique: World Congress on Emulsion 2010

2010-07-23T16:01:00.003+02:00

Contribution to the 5th world congress on emulsion CME
12 - 14 October, Lyon, France

`A comparative study of asphaltene precipitation/flocculation by a new non-scanning NIR-technique in accordance with ASTM D 7061`

St. Küchler, T. Sobisch, A. Uhl, D. Lerche

LUM

Rudower Chaussee 29 (OWZ) 12489 Berlin / Germany

info@lum-gmbh.de, www.lum-gmbh.com

Abstract

Asphaltenes and its derivatives, which are present in crude oil emulsions , may create severe technical and economical problems when they precipitate. Especially the flocculation of asphaltenes in heavy fuel oils may cause severe problems, including reservoir plugging, fouling of production facilities, altering wettability and poisoning refinary catalysts. Therefore the prediction and prevention of asphaltene flocculation is a crucial task for technical and laboratory staff in R&D, QC and production.

From the various methods that have been suggested over the years to serve this task the ASTM D 7061-05a has become an industrial standard to quantify and predict asphaltene flocculation in crude oils and heavy fuels.

In this contribution a non-scanning NIR-technique will be applied to measure asphaltene stability according to ASTM D 7061-05a by space and time resolved extinction (transmission) profiles (STEP-Technology). This apparatus (LUMiReader®, LUM GmbH) has the capability to measure simultaneously in 3 channels at tontrolled temperature up to 60°C.

Nine different crude oils with and without inhibitor were studied.

For direct comparison the same samples have been analyzed by the scanning apparatus described in the ASTM D 7061-05a.

The Separability Numbers, calculated from the measurements with the non-scanning NIR-apparatus, range from 0.2 to 15 showing a very good reproducibility and a very good agreement with the scanning technique. The applied non-scanning NIR-apparatus therefore is able to serve the broad spectra of crude oils in the market.

Keywords: Crude oil, heavy fuel oil, Induced Phase Separation of Asphaltene, Separability Number, STEP-Technology

test for long term stability - bottom focused back scattering World Congress on Emulsion 2010

2010-07-23T15:57:00.000+02:00

Contribution to the 5th world congress on emulsion CME
12 - 14 October, Lyon, France

Easing formulation of emulsions and test for long term stability using bottom focussed back scattering

T. Sobisch, U. Rietz, D. Lerche

LUM

Rudower Chaussee 29 (OWZ) 12489 Berlin / Germany

info@lum-gmbh.de, www.lum-gmbh.com

Abstract

Selection of efficient emulsifiers, their optimum concentration and of the processing conditions is a demanding and time consuming process. Evaluation of emulsion stability can be eased when focussing on the changes in droplet concentration right at the bottom part of the emulsion samples. Furthermore the level of the back scattering signal is directly related to the dispersion degree. Thus the initial back scattering signal can be used to compare emulsification quality and to detect loss in dispersity due to aging.

The method was applied to trace the optimum emulsifier concentrations for silicone oil emulsions to evaluate the influence of processing intensity. Further the method was used to detect the very first changes of sample dispersity after accelerated aging.

Results demonstrate that bottom focussed back scattering can be applied as tool in every day formulation work and that during accelerated aging tests the method can serve as a sensitive measure of loss of dispersion integrity.

Keywords: formulation, emulsifier selection, processing conditions, accelerated aging, bottom focussed back scattering

Inlined creaming, speeding-up stability evaluation - World Congress on Emulsion 2010

2010-07-23T15:52:00.003+02:00

Contribution to the 5th world congress on emulsion CME
12 - 14 October, Lyon, France

Speeding up the evaluation of emulsion stability during normal storage conditions

T. Sobisch, D. Lerche

LUM

Rudower Chaussee 29 (OWZ) 12489 Berlin / Germany

info@lum-gmbh.de, www.lum-gmbh.com

Abstract

The principle of inclined settling is often used in separation technology to increase capacity and efficiency of settling aggregates. The Boycott effect is also applied in clinical tests to speed-up the evaluation of blood samples.

To answer the question whether this approach can also be used to speed up the evaluation of emulsion stability tests were carried out with colloidal stable emulsions (stable against aggregation and coalescence) and flocculated emulsions.

The LUMiReader instrument (LUM, Germany) can measure space and time resolved extinction (transmission) profiles (STEP technology) in multiple channels using near infrared (NIR) or visible light. This way it measures changes in turbidity and the movement of the boundary towards the supernatant. Even more the angle of inclination can be varied between 0 and 30° from the vertical.

Investigations on creaming as function of angel of inclination were carried out on nonflocculated silicone oil-in-water emulsions varying the oil concentration and on flocculated silicone oil-in-water emulsions at different electrolyte concentration.

The same principle behaviour as in case of monodisperse colloidal stable silica was found for the polydisperse colloidal stable (nonflocculated) emulsion. In this case ‘inclined creaming’ proceeds. At 30° inclination the creaming can be accelerated by a factor of about 9, i.e. the necessary time for stability evaluation can be shortened accordingly.

The creaming rate dependence on inclination is rather unpredictable for flocculated network forming emulsions. A maximum in creaming rate was observed around 25° inclination. In case of the emulsion with 0.5 M NaCl this relates to an enhancement factor of over 25, however, for 0.75 M NaCl it is only slightly higher than 1.

Keywords: enhanced creaming, Boycott effect, emulsion stability, creaming velocity, salt induced flocculation

Rapid emulsifier selection, emulsion stability, reformulation - World Congress on Emulsion 2010

2010-07-23T15:42:00.002+02:00

Contribution to the 5th world congress on emulsion CME
12 - 14 October, Lyon, France

Rapid emulsifier selection and evaluation of emulsion stability for reformulation

T. Sobisch, D. Lerche, LUM

Rudower Chaussee 29 (OWZ) 12489 Berlin / Germany

info@lum-gmbh.de, www.lum-gmbh.com

Abstract

A multisample technique based on analytical centrifugation is presented which allows for an accelerated study of creaming, sedimentation and of separation of oil and water phases. Not only information on the extent of phase separation is provided but also the kinetics are measured directly in-situ.

The method was applied to check for alternatives to nonyl phenol based surfactants as emulsifiers for silicone oil emulsions. Different commercial products were evaluated. It proved to be a very efficient screening method, which can be also applied in every day formulation work.

Due to the multisample approach one centrifugal run with 12 different samples was sufficient to identify more environmentally benign emulsifiers with identical or better performance. In a second run the efficiency of emulsifier combinations was tested. The primary destabilization mechanism for all emulsions was creaming, however, most emulsions showed phase inversion when a critical phase ratio was reached inside the cream layer. By increasing the polarity of the alternative emulsifiers the risk of phase inversion could be rigorously reduced.

Keywords: reformulation, REACH, emulsifier selection, silicon oil-in-water emulsions, creaming kinetics, analytical centrifugation

Surfactant adsorption kinetics - emulsion stability, World Congress on Emulsion 2010

2010-07-23T15:28:00.002+02:00

Contribution to the 5th world congress on emulsion CME
12 - 14 October, Lyon, France

Interrelation between surfactant adsorption kinetics, interfacial rheology and emulsion stability

T. Sobisch1, N. Mucic2, J. Krägel2, A.V. Makievski3, R. Miller² and D. Lerche1

1 LUM GmbH, Rudower Chaussee 29 (OWZ) 12489 Berlin / Germany
info@lum-gmbh.de, www.lum-gmbh.com
² MPI für Kolloid- und Grenzflächenforschung, Am Mühlenberg 1, 14424 Potsdam / Germany
3 SINTERFACE Technologies, Volmerstrasse 5, 12489 Berlin / Germany

Abstract
The right choice of emulsifier is an ongoing challenge in emulsion technology. The time scale of the emulsification process has a strong impact on the emulsifier efficiency, which can only become effective if the adsorption kinetics are fast enough to avoid coalescence of freshly formed droplets. Additionally, the interfacial rheology at the oil-water interface determines the final emulsion stability.
The interrelation between surfactant adsorption kinetics, interfacial rheology and emulsion stability was investigated in model systems paraffin oil / water / nonionic surfactants, where the EO-chain length was varied.
The kinetics and thermodynamic properties of the surfactants at the oil/water interface were measured by using drop profile analysis tensiometry. The same tool is applied for the investigation of the interfacial dilational rheology by recording the interfacial tension response to harmonic area compressions-expansions of the studied drop.
Emulsions were prepared with a dissolver type homogenizer. Stability of emulsions was investigated as function of time of processing, surfactant concentration and HLB value using multisample analytical centrifugation. Not only the extent of phase separation but also the kinetics are directly measured in-situ.
Emulsion stability increases with time of emulsification. The emulsifier with 5 EO units is far more effective than that with 12 EO units. Adsorption equilibrium at the interface is reached in seconds. The kinetics of adsorption show clearly a depletion effect of surfactant molecules from the aqueous phase, which is especially pronounced for the emulsifier with 5 EO units. Nevertheless, at higher surfactant concentration the interfacial tension is lower for the more lipophilic surfactant.

Keywords: emulsion stability, adsorption layer properties, analytical centrifugation, emulsion preparation, emulsifier selection, oil-in-water

Characterization of the dispersion properties of carbon nanotubes in ionic liquids by the separation behaviour in the centrifugal field

2010-06-28T09:38:00.005+02:00

Characterization of the dispersion properties of carbon nanotubes in ionic liquids by the separation behaviour in the centrifugal field

T. Sobisch, D. Lerche

LUM Berlin/Germany www.LUM-gmbh.com

Y. Korth, C. Friedrich

Albert-Ludwigs-Universität Freiburg/Germany www.fmf.uni-freiburg.de

Scope

Carbon nanotubes are considered as nano materials with a broad application potential, e.g. as filler, in electronic devices and batteries. The relatively good dispersibility in ionic liquids is an interesting approach.

Carbon nanotubes in ionic liquids tend to form extended inter-tangled fibre networks, however, for efficient application a high degree of dispersion is required.

In this study dispersions of different multiwalled carbon nanotube products in 1-butyl-3-methyl-imidazoliniumtetrafluoroborat (BMIBF4) were characterized by multisample analytical centrifugation with high resolution photometric detection. Based on the sedimentation/consolidation behaviour pronounced differences in the degree of network formation and in the packing density were identified. The size distribution of the products was also determined by multisample analytical centrifugation.

Carbon nanotube dispersions [1]

Raw materials

Fig. 1 Overview over materials used and below related TEM pictures

The 3 different products used differ largely in material properties and morphology (Fig. 1)

Dispersion preparation

In a first step the nanotubes were dispersed in ethanol by sonication. After adding BMIBF4 sonication was repeated and in a third step the ethanol was evaporated. Dispersions of 1 % m/m were prepared. For the centrifugal analysis dispersions were further diluted to 0.1 % m/m.

Method of multisample analytical centrifugation

Time and space resolved detection of light transmission (STEP-Technology) combined with multisample analytical centrifugation (LUMiSizer, LUM, Germany, [2-4]) was applied, which measures concentration changes inside the sample by high resolution photometric detection (see Fig. 2).

Fig. 2 Measurement scheme of the multisample analytical centrifuge. Local changes are detected during centrifugation. The distribution of transmission is recorded over the whole sample length at predefined time intervals.

Up to 12 different samples can be analysed at the same time at constant or variable centrifugal acceleration up to 2300 g. The shape and progression of the transmission profiles contain the information on the dispersion properties. The transmission profiles (Fig. 4) are representative for the distribution of particle concentration inside the sample (low transmission means high, high transmission means low particle concentration). Based on this, sedimentation and clarification kinetics, the dependence between packing density and pressure, as well as the velocity and particle size distribution can be obtained. Polycarbonate cells with an optical path length of 2.1 mm were used.

Results and discussion

Size distributions

Fig. 3 Comparison of the cumulative intensity weighted distribution of the 3 products.

The particle size is obtained as equivalent particle diameter according to the hydrodynamic diameter of spherical particles. Therefore the large asymmetry of the nanotubes will have a pronounced impact on these results. Nevertheless, it can be seen that the Nanocyl product has a narrower distribution and lacks the coarse fraction present in the two other products.

Separation behaviour as function of raw material

Fig. 4 Transmission profiles obtained during 2 hours centrifugation at 2300 g as function of the raw material used (first profile after 10 seconds in red, last profile after 2 hours in green).

As obvious from Fig. 4 the evolution of transmission profiles during centrifugation can be used as finger print to distinct the 3 products. All 3, especially Nanocyl, exhibit a different behaviour.

The transmission profiles depict the transmission as function of the position inside the sample given as distance from the centre of rotation.

In case of Nanocyl sharp vertical profiles are obtained showing that all particles move with identical velocity. The distance between the consecutive profiles is narrowing due to the resistance to compaction is increasing with the packing density obtained. This is characteristic for a flocculated particle network, in this case for a network of entangled nanotubes. For the other 2 products there is no sharp sedimentation front, instead the transmission is gradually decreasing towards the cell bottom. This relates to a polydisperse sedimentation, the particles or aggregates/agglomerates move with different velocity. It can be further noticed that for these two dispersions sediment (range of minimum transmission close to the bottom) is formed instantaneously followed by a gradual increase of transmission in the supernatant. Therefore, it can be concluded that there is a fast settling of aggregates/agglomerates followed by the separation of fines.

On a closer look for Polytech&Net one can observe a gradual compression of the instantaneously formed sediment (particle network).

According to the sediment height the order of packing density is:

Nanocyl <>

From the comparison of the transmission profiles it can be concluded that the Iolitek has the highest dispersibility, Nanocyl has a pronounced tendency to form an entangled network.

Influence of the degree of ultrasonication on separation kinetics

Fig. 5 Separation kinetics as function of intensity of sonication for the centrifugation of 0.1 % dispersion of Nanocyl in BMIBF4 at 2300 g.

For Nanocyl the intensity of sonication during dispersion was varied, abbreviated as CE.10.42, CE.10.43, CE.65.45 (amplitude and duration: 10 % 5 min / 10 % 8 min / 65% 16 min). Fig. 5 exhibits the related separation kinetics (movement of the boundary supernatant/dispersion with time). Increasing the sonication intensity the separation slows down and the equilibrium sediment height increases (difference between position of the cell bottom and the position of the boundary towards the sediment), i.e. the packing density decreases.

Fig. 6 Compression-dilation kinetics of the sediment formed after 2 hours centrifugation in Nanocyl dispersions as function of sonication intensity. The centrifugal acceleration was increased step-wise and then decreased.

As shown in Fig. 6 sediments formed in case of Nanocyl (compacted particle network) exhibit elastic behaviour. The packing density calculated from sediment volume and particle concentration decreases with intensity of sonication.

References

[1] Y. Korth, PhD thesis Rheologische und morphologische Eigenschaften von Fasernetzwerken

Freiburg i. Breisgau, Univ., Diss., 2010

http://www.freidok.uni-freiburg.de/volltexte/7491/pdf/Dissertation_Yasmin_Korth_5.5.2010.pdf

[2] D. Lerche, Dispersion stability and particle characterisation by sedimentation kinetics in a centrifugal field

J. Dispersion Sci. Technol. 23, 5, 699 ‑ 709 (2002)

[3] G.G. Badolato, F. Aguilar, H.P. Schuchmann, T. Sobisch and D. Lerche, Evaluation of long term stability of model emulsions by multisample analytical centrifugation,

Progr. Colloid Polym. Sci. 134 66–73 (2008)

[4] T. Sobisch and D. Lerche, Thickener performance traced by multisample analytical centrifugation

Colloids & Surfaces A 331 114-118 (2008)

Bisphenol A Massenchemikalie mit unerwünschten ... UBA Hintergrundpapier

2010-06-22T13:32:00.002+02:00

Bisphenol A - Massenchemikalie mit unerwünschten Nebenwirkungen

Hintergrundpapier Umweltbundesamt

'Bisphenol A war eine der ersten synthetischen
Substanzen, von der bekannt wurde, dass sie das natürliche
weibliche Sexualhormon Östrogen in der
Wirkung nachahmen kann. Die britischen Biochemiker
Edward Charles Dodds und Wilfrid Lawson suchten
1936 nach Chemikalien, die in der Lage waren, in
der medizinischen Therapie das natürliche Östrogen zu
ersetzen. Dieses weibliche Hormon war extrem teuer,
da es bis dahin aufwändig aus dem Urin schwangerer
Stuten aufbereitet werden musste.....
Bisphenol A steckt in vielen Alltagsprodukten: in CDs
und DVDs, im Kassenzettel aus Thermopapier oder in
Plastikschüsseln. Doch was ist Bisphenol A, wofür wird
es eigentlich verwendet und in welchen Mengen?'

Zusammenfassung
Bisphenol A ist in vielen Produkten unseres täglichen
Lebens. Der größte Teil des produzierten Bisphenol A
wird zu stabilen Kunststoffen verarbeitet (Polykarbonat
und Epoxidharzen). Unter bestimmten Bedingungen
kann sich die Chemikalie aus Gebrauchsgegenständen
lösen – wie aus der Beschichtung von Dosen – und
über die Nahrung oder über die Haut – wie bei
Thermopapier – in den menschlichen Körper gelangen.
Hier kann die Substanz wie das weibliche
Sexualhormon Östrogen wirken.
Bisphenol A gelangt auch in den Wasserkreislauf
und somit in den Körper von Wasserorganismen.
Messungen der letzten Jahre wiesen Bisphenol A in vielen
Gewässern nach. Der Stoff stammt im Wesentlichen
aus den Kläranlagen der Unternehmen, die Bisphenol A
produzieren und verarbeiten.
Besteht ein Risiko für Mensch und Umwelt? Sind darum
gesetzliche Maßnahmen zum Schutz vor Bisphenol A
notwendig?
Zahlreiche Studien belegen, dass Bisphenol A in das
Hormonsystem von Säugern und Gewässerorganismen
eingreift. Es gibt Untersuchungen, die der Chemikalie
bereits bei niedrigen Konzentrationen negative
Effekte auf die Sexualität sowie einen Zusammenhang
mit dem Auftreten von Diabetes und Herz-
Kreislauferkrankungen nachweisen. Zudem gibt es
Hinweise darauf, dass der Stoff die Entwicklung geistiger
Fähigkeiten und des Verhaltens beeinträchtigen
kann und Aggressivität fördert und Lernen hemmt. Die
wissenschaftlichen Ergebnisse, die bis heute vorliegen,
sind jedoch nicht ohne Widersprüche. Viele Studien
werden von Wissenschaftlern kontrovers diskutiert.
Auch für einige Tierarten (z.B. Schnecken) stellen
Studien fest, dass Bisphenol A bereits in sehr niedrigen
Konzentrationen die Fortpflanzung stört. Jedoch ist die
Auswertung dieser Ergebnisse umstritten, da viele dieser
Tests methodische Mängel haben.
Im EU-Altstoffprogramm gemäß Altstoffverordnung
(EWG) Nr. 793/93 bewerteten die EU-Mitgliedstaaten
das Risiko von Bisphenol A für Mensch und Umwelt.
Das Ergebnis: bei sachgemäßer Verwendung von
Produkten auf Bisphenol A-Basis besteht für die
Verbraucherinnen und Verbraucher kein Anlass zur
Sorge vor gesundheitlichen Gefahren. Auch die europäische
Lebensmittelbehörde EFSA kommt zu diesem
Schluss. Nicht alle EU-Länder teilen ein so eindeutiges
Ergebnis. Dänemark und Frankreich zum Beispiel
haben vorsorglich weitergehende Maßnahmen für
bestimmte Produkte erlassen. Kanada hat inzwischen
aus Vorsorgegründen Bisphenol A-haltige Babyflaschen
verboten. Auch aus der fachlichen Sicht des UBA ergibt
sich ein ausreichendes Besorgnispotenzial. Zahlreiche
wissenschaftliche Befunde ergeben insgesamt ein
konsistentes Bild, so dass trotz der Unsicherheiten
und Wissenslücken bei der Risikobewertung und der
Expositionshöhe Handlungsbedarf besteht. Das UBA
spricht sich darum dafür aus, vorsorgend tätig zu
werden und die Verwendung einiger Produkte, die
Bisphenol A enthalten, zu beschränken.
Auch für die Umwelt bewertet die EU das Risiko als
vertretbar. Die errechneten Konzentrationen in der
Umwelt liegen deutlich unterhalb der Werte, bei denen
Wirkungen auf Boden- und Wasserorganismen zu erwarten
sind. Gleichzeitig liefern verschiedene Studien
Anhaltspunkte dafür, dass das Risiko für Gewässer- und
Sedimentorganismen möglicherweise bisher unterschätzt
wird.
Mit der europäischen Chemikalienverordnung REACH
stehen die Bisphenol A-Hersteller und Verwender in
der Pflicht, ihre Eigenverantwortung wahrzunehmen.
Sie müssen darstellen, unter welchen Bedingungen
Bisphenol A über den gesamten Lebensweg sicher
verwendet werden kann. Falls nötig müssen sie hierzu
Risikominderungsmaßnahmen einleiten.
Diese Informationen wird das Umweltbundesamt verwenden,
um die Risikobewertung für Bisphenol A zu
überprüfen. Das UBA wird dann entscheiden, ob aus
fachlicher Sicht zusätzliche gesetzliche Maßnahmen zur
Risikominderung in der Umwelt notwendig und der EU
zu empfehlen sind. Dabei sind für Bedarfsgegenstände
mit Bisphenol A auch produktrechtliche
Regelungsoptionen zu prüfen. Grundsätzlich empfiehlt
das UBA, den Gehalt von Bisphenol A in Produkten weiter
zu begrenzen. Außerdem rät das UBA Herstellern,
Importeuren und Verwendern von Bisphenol A, für alle
Einsatzgebiete des Stoffes, die wesentlich zu Exposition
von Mensch und Umwelt beitragen, gesundheits- und
umweltfreundlichere Alternativen zu verwenden. Damit
kann ein wichtiger Beitrag zur Produktverantwortung
bei einem Stoff, bei dem vorsorglicher Schutz von
Mensch und Umwelt angezeigt ist, geleistet werden.

"Blühende Landschaften" am Hindukusch?

2009-12-11T12:19:00.002+01:00

medico - Bewertung aus der Sicht einer deutschen Hilfsorganisation

"Blühende Landschaften" am Hindukusch?

Rede von medico-Geschäftsführer Thomas Gebauer. Gehalten auf der Konferenz "Mission impossible am Hindukusch? - Zwischenbilanz der neuen internationalen Afghanistan-Politik" am 24.11.2009 in Berlin. Veranstaltet wurde die Konferenz vom Verband Entwicklungspolitik deutscher Nichtregierungsorganisationen (VENRO).

Kriegerische Zustände herrschen in Afghanistan bekanntlich nicht erst seit gestern. Nicht die Lage ist neu, wohl aber der Minister, der sie kommentiert. Und da hat sich offenbar etwas verändert. Statt die Dinge weiter Schönzureden, könnte nun endlich auch dort Klartext geredet werden, wo über die Entsendung von Soldaten entschieden wird: im Bundestag.

Sie alle kennen die sprachlichen Verrenkungen, die in den letzten Jahren die Runde machten. Statt von Krieg war von Stabilisierungseinsatz die Rede, statt von Aufstandsbekämpfung von einer Friedens- und Wiederaufbaumission, von Soldaten als Aufbauhelfer - ja selbst von Tornados zur Planung von Infrastrukturprojekten, wie mir Abgeordnete des Deutschen Bundestages zu versichern versuchten. Ein einziger Eiertanz, den wir, den entwicklungspolitisch tätige NGOs immer mit größter Skepsis verfolgt haben.

Warum? – Auch darum wird es gehen, wenn ich Ihnen im Folgenden die Lage in Afghanistan aus der Perspektive von Hilfsorganisationen, die vor Ort tätig sind, schildern werde. Ausgangspunkt für mich sind zunächst eigene Erfahrungen, Besuche vor Ort, Gespräche mit Partnern, dann aber auch die Erfahrungen meiner Kollegen bei medico international, schließlich all das, was andere NGOs berichten, was wir untereinander austauschen und zuletzt in einem gemeinsamen Positionspapier unter dem Dach von VENRO zusammengetragen haben. Dessen Forderungen werde ich Ihnen gegen Ende meiner Ausführungen im Einzelnen erläutern.

..........................

So sehr wir auf rasche und spürbare Verbesserungen drängen, steht für uns doch auch fest, dass nachhaltige Veränderungen nicht von heute auf morgen gelingen werden. Voraussetzungen sind partizipative Prozesse, in die alle relevanten Akteure eingebunden werden müssen, begleitet von Verhandlungen und vertrauensbildenden Maßnahmen, um schließlich langfristig angelegte Aufbauprogramme zu definieren, die nicht von außen übergestülpt werden und am Ende nur der Legitimation bzw. der Absicherung von Truppenpräsenz dienen.

III.

Lassen Sie mich abschließend noch mal auf die Äußerungen von Verteidigungsminister Guttenberg zu sprechen kommen. In seinem Focus-Interview hat er auch gesagt, dass – und ich zitiere – "dass man in Afghanistan an seine Grenzen stößt, wenn man von einer Demokratie westlichen Stils zu träumen beginnt. Ein solcher Traum ist mit den Realitäten vor Ort nicht vereinbar. Auch dieser Traum hat uns viel Zeit gekostet".

Mit Blick auf die Verhältnisse, die in Afghanistan herrschen, mag auch darin etwas Zutreffendes zum Ausdruck kommen. Gewiss war die Idee naiv gewesen, das Modell des OECD-Staates nach Afghanistan exportieren zu wollen. Dennoch kann ich mich nicht ganz des Eindrucks erwehren, dass er für die Grenzen, auf die man in Afghanistan nun stößt, vor allem die Afghanen selbst verantwortlich machen will.

So notwendig realistische Einschätzungen sind, so wenig darf dabei übersehen werden, dass die Sache der Afghanen schon lange nicht mehr die Sache der Afghanen alleine ist. Auch der Westen hat über Jahrzehnte hinweg heftig Einfluss genommen. Mit dem Argument, Freiheit und Demokratie verteidigen zu wollen, hat er den Kampf der Mujaheddin gegen die sowjetische Besatzung finanziert. Später hat er zusehen, wie das Land von eben den Mujaheddin vollends in Schutt und Asche gelegt wurde. Er hat, in der Hoffnung, endlich wieder einen Garant für Stabilität gefunden zu haben, der sich obendrein noch als Bündnispartner in den Auseinandersetzungen mit dem Iran anbot, Mitte der 90er Jahre die Bildung der Taliban unterstützt. Und er hat dann 2001 erneut mit den Mujaheddin und Warlords gemeinsame Sache gemacht, als es darum ging, die Taliban wieder aus Afghanistan zu vertreiben.

2001, zu Beginn des internationalen Engagements, standen die Voraussetzungen für die Herausbildung demokratischer Verhältnisse nicht einmal schlecht. Mit großem Enthusiasmus beteiligten sich die Afghanen an der Loya Jirga und stimmten für eine neue Verfassung. Der Moment, in dem die Demokratie scheiterte, war, als der damalige US-Botschafter und die UN dafür sorgten, dass in der Loya Jirga neben den gewählten Delegierten auch 50 Plätze für die Warlords reserviert wurden. Es waren die Afghanen, denen mit diesem skandalösen Akt die Grenzen für den Traum ihrer Demokratie aufgezeigt wurden. Um sich selber die Finger nicht schmutzig machen zu müssen, hatte der Westen mit Kriegsverbrechern paktiert, mit anderen Worten: den Teufel mit dem Beelzebub ausgetrieben.

Wer so vorgeht, muss sich nicht wundern, wenn Demokratie scheitert. Nicht eine vermeintliche Rückständigkeit der Afghanen steht dem Traum demokratischer Verhältnisse entgegen, sondern die Art und Weise wie der Westen in den letzten Jahrzehnten von außen eingegriffen hat. Taliban, Warlords, Milizen, Drogenbarone – sie alle sind nichts anderes als die Gespenster der Ruinen gescheiterter Interventionen.

SEDIMENTATION AND CONSOLIDATION BEHAVIOUR OF KAOLIN SUSPENSIONS IN PRESENCE OF DISPERSANT

2009-08-13T13:44:00.002+02:00

FILTECH 2009 International Conference Exhibition for Filtration and Separation Technology
October 13 - 15 Wiesbaden Germany

Characterization of sedimentation and consolidation behaviour of kaolin suspensions in presence of dispersant

T. Sobisch², C. Le Coeur¹, T. Detloff², A. Zierau², O. Larue¹.D. Lerche², E. Vorobiev¹

¹ Université de Technologie Compiègne / Département Génie Chimique, Compiègne/France

² LUM / 12489 Berlin / Germany

During processing and application of kaolin usually dispersants are used. For optimization evaluation of the sedimentation behaviour of the suspensions can deliver important information. To this end a method for comprehensive characterization of this process is required.

Space and time resolved photometric methods using near infrared (NIR) light enable the measurement of the movement of the boundary towards the supernatant and to characterize clarification processes. X-rays on the other hand give information on concentration profiles in sediment and suspensions. These two methods complement each other to characterize sedimentation and consolidation behaviour.

In this paper the sedimentation and consolidation behaviour of kaolin suspensions was studied by multisample analytical centrifugation with photometric detection. Kaolin, dispersant concentration and centrifugal acceleration was varied. After dewatering of the sediments in the centrifugal field, the distribution of packing density was determined using X-ray measurements.

LABORATORY SCALE EVALUATION OF INCLINED SETTLING

2009-08-13T13:32:00.002+02:00

FILTECH 2009 International Conference Exhibition for Filtration and Separation Technology
October 13 - 15 Wiesbaden Germany

Laboratory scale evaluation of inclined settling

T. Sobisch, D. Lerche, LUM, Berlin/Germany

The principle of inclined settling is often used in practise to increase capacity and efficiency of settling aggregates. The settling rate in inclined-plate (lamella) and tube settlers is influenced by two factors, the effect of gravity acting on the particles and the settling rate due to the presence of inclined surfaces. The increase in settling rate exhibits a complex dependence on material properties (solids density and size distribution, concentration, surface properties, liquid properties) and the angle of inclination. So far adjustment of operating conditions is done empirically or based on pilot or field scale experiments. A preselection based on lab scale experiments would be beneficial.

The LUMiReader instrument can measure space and time resolved extinction (transmission) profiles (STEP technology) in multiple channels using near infrared (NIR) or visible light. This way it measures changes in turbidity and the movement of the boundary towards the supernatant. Even more the angle of inclination can be varied between 0 and 30° from the vertical.

Investigations on settling as function of angel of inclination were carried out on lime suspensions with varying solids concentration.

FLOCCULATED DISPERSIONS CHARACTERIZED BY DIFFERENT METHODS MEASURING TRANSMISSION

2009-08-13T13:00:00.002+02:00

FILTECH 2009 International Conference Exhibition for Filtration and Separation Technology
13 - 15 October 13 - 15 Wiesbaden Germany

sedimentation and consolidation behaviour of Flocculated Dispersions Characterized by different methods measuring transmission

T. Sobisch¹, A. Zierau¹, A. Bjeoumikov², M. Holke³, D. Lerche¹

¹ LUM, ² IFG GmbH, ³ IAP e.V., Berlin/Germany

During technical application and during solid-liquid separation dispersions are often flocculated. While during application sedimentation and consolidation usually have to be avoided or minimized, for solid-liquid separation these are essential. In both cases there is a need for fast reliable methods for comprehensive characterization of these processes.

Space and time resolved photometric methods using near infrared (NIR) light are well suited to measure kinetics of sedimentation and clarification. Using X-rays additional information on concentration profiles in sediments and highly concentrated suspensions can be obtained. Therefore photometric and X-ray measurements can ideally complement each other.

Investigations on sedimentation and consolidation behaviour of flocculated polydisperse quartz suspensions are presented. These were carried out at normal earth gravity as function of flocculant concentration using both transmission measurements with NIR light and X-rays. This was followed by measurement of the compressional behaviour of the sediments formed at earth gravity. To this end multisample analytical centrifugation with photometric detection was used. After dewatering of the sediments in the centrifugal field the space resolved distribution of packing density inside the sediments was determined measuring X-ray transmission.

Qualitätskontrolle und Stabilitätsuntersuchungen an Wasserlacken

2009-08-13T10:36:00.002+02:00

GDCh - Lacktagung 2009 - Wasserlacke überall
23.-25.09.2009 Überlingen Germany

Qualitätskontrolle und Stabilitätsuntersuchungen an Wasserlacken mittels Analytischer Zentrifugation

Sobisch, T., Uhl, A., Lerche, D., LUM Berlin/D

Wasserlacke sind Dispersionen. Deshalb ist nicht nur die mikrobiologische und chemische, sondern auch die Entmischungsstabilität der Produkte zu prüfen. Diese Aufgabe ergibt sich sowohl in Bezug auf die Entwicklung neuer Produkte als auch für die Qualitätskontrolle.

Es wird eine Multiprobentechnik vorgestellt, die mittels Analytischer Zentrifugation eine beschleunigte Charakterisierung von Entmischungsprozessen (Aufrahmung, Sedimentation, Koaleszenz, Phasenseparation) erlaubt. Hierbei kann die Kinetik dieser Destabilisierungsprozesse direkt zeitgleich für bis zu 12 verschiedene Proben bestimmt werden.

Die Analytische Zentrifugation mißt die den Proben inhärente Stabilität. Erst in der Zukunft ablaufende Destabilisierungsprozesse, die auf langsamen Diffusionsprozessen beruhen, können nicht vorhergesehen werden. In dieser Hinsicht empfiehlt sich eine Kombination mit gängigen Alterungstests. Neben der direkten und indirekten Messung der Dispersionsstabilität kann die Dispersionsstruktur (geflockt/nicht geflockt) und Art der Partikelwechselwirkungen (attraktiv oder repulsiv) sowie die Partikelgrößenverteilung der Produkte charakterisiert werden.

Konzentrationsprofile innerhalb der sich bildenden Sedimente wurden mittels ortsaufgelöster Messung der Röntgentransmission gemessen.

Die Leistungsfähigkeit der Methode wird am Beispiel ausgewählter Wasserlacke insbesondere in Bezug auf pH und Temperatureinfluß belegt.

ACHEMA2009 - Paint products: Accelerated stability and quality testing by direct measurement of separation and segregation

2009-04-29T12:35:00.002+02:00

Paper at

ACHEMA 2009
29th International Exhibition-Congress on Chemical Engineering, Environmental Protection and Biotechnology
11 - 15 May 2009 Frankfurt am Main / Germany

T. Sobisch, D. Lerche, LUM Berlin/Germany

Paper 7401, 05/11/09 4 p.m.

Paint products: Accelerated stability and quality testing by direct measurement of separation and segregation

To assure continued consumer satisfaction the following stability issues of paint products have to be minimized or avoided:

• Syneresis – separation of the liquid dispersion media
• Pigment segregation – change of colour composition inside a container
• Particle segregation – change of particle size distribution inside a container

These stability issues have to be addressed not only during development of new paint products but also for quality assurance during production on a regular basis. This paper demonstrates that multisample analytical centrifugation can be used as an efficient tool for the accelerated evaluation of separation stability of paint products.
In addition this technique provides for high resolution data of particle size distributions of pigments or emulsions.

ACHEMA2009 - Photometric instrumentation for evaluation of dispersion stability and optimization

2009-04-29T12:28:00.002+02:00

Paper at

ACHEMA 2009
29th International Exhibition-Congress on Chemical Engineering, Environmental Protection and Biotechnology
11 - 15 May 2009 Frankfurt am Main / Germany

T. Sobisch, T. Detloff, U. Rietz, D. Lerche, LUM Berlin/Germany

Paper 7404, 05/14/09 2 p.m.

Photometric instrumentation for evaluation of dispersion stability and optimization of separation and stabilization of dispersions

Dispersion stability – in one way or the other - is a hot topic in many industries (cosmetics, ceramics, pharmaceutics, paints, mining etc.). Mostly high dispersion stability is required, however, separation of dispersions is the issue in other fields.
From this it is evident that formulation of products as well as process and quality control is in need of efficient measurement techniques.
The paper proposes the use of high resolution photometric detection of transmission profiles (LUMiReader) and the use of bottom focussed backscattering (LUMiCheck).
These techniques allow for an accelerated study of dispersion demixing. The LUMiReader provides information on the extent of phase separation but also on the kinetics of the underlying processes directly in-situ. The LUMiCheck is used to measure sedimentation and creaming with high sensitivity by focussing on changes in particle concentration right at the bottom part of the dispersions.
The potential of these methods was demonstrated on several systems by screening for the most efficient dispersants, preparation conditions and also for selection of conditions to separate dispersions.

ACHEMA2009 - Speeding up the evaluation of the physical stability of beverage dispersions

2009-04-29T12:20:00.002+02:00

Paper at

ACHEMA 2009
29th International Exhibition-Congress on Chemical Engineering, Environmental Protection and Biotechnology
11 - 15 May 2009 Frankfurt am Main / Germany

T. Sobisch, D. Lerche, LUM Berlin/Germany

Paper 7403, 05/11/09 11 a.m.

Speeding up the evaluation of the physical stability of beverage dispersions

Reduction of turbidity and phase separation is an important problem for the beverage industry. Traditional methods of stability evaluation are visual observations (over several months) and measurement of opacity, droplet size index particle size analysis during storage.
Alternatively high resolution photometric detection of transmission profiles with a LUMiReader instrument is proposed.
This technique allows for an accelerated study of beverage demixing by providing information on the extent of phase separation but also on the kinetics of the underlying processes directly in-situ. This is of great practical importance for evaluation of shelf life but is also very useful in screening of additives for more stable formulations.
The method was tested for a range of beverages with the focus on beverage emulsions.

ACHEMA2009 - Additive selection and evaluation of dispersion stability for reformulation in the REACH process

2009-04-29T11:58:00.002+02:00

Paper at

ACHEMA 2009
29th International Exhibition-Congress on Chemical Engineering, Environmental Protection and Biotechnology
11 - 15 May 2009 Frankfurt am Main / Germany

T. Sobisch, D. Lerche, LUM Berlin/Germany

Paper 7402, 05/15/09 11 a.m.

Rapid additive selection and evaluation of dispersion stability for reformulation in the REACH process

Selection of additives for stabilization of dispersions is a frequent task. This relates to practical issues like formulation of dispersions, optimization of preparation conditions, quality control and shelf life estimation. Due to European legislation (REACH) many companies are facing the problem to replace proven components in their formulations (low volume speciality compounds or problematic chemicals). This also applies to emulsifiers and emulsion based products.

A multisample technique based on analytical centrifugation is presented which allows for an accelerated study of demixing of dispersion like creaming, sedimentation and of separation of oil and water phases. Not only information on the extent of phase separation is provided but also the kinetics are measured directly in-situ. The latter is of great practical importance for estimation of shelf life and in relation to the engineering of separation processes but is also very useful in screening of additives for replacement.

The method was applied to check for alternatives to nonyl phenol based surfactants as emulsifiers for silicone oil emulsions. Due to the multisample approach one centrifugal run with 12 different samples was sufficient to identify more environmentally benign emulsifiers with identical or better performance. In a second run the efficiency of emulsifier combinations was tested.

Campact Studie Verbot Genmais

2009-04-06T12:40:00.002+02:00

Campact: 'Die Chancen stehen nicht schlecht für ein Verbot von Gen-Mais MON810 (in Deutschland'.
...
Aigners Abteilungsleiter für Gentechnik erklärte im Gespräch mit uns, ein Verbot nach der Schutzklausel zu prüfen. Wir sollten ihm hierfür nur genügend aktuelle Risikostudien zusammenstellen. Das ließen wir uns nicht zweimal sagen: Innerhalb weniger Tage stellten uns der Gentechnik-Experte Christoph Then und eine Rechtsanwältin ein Gutachten zusammen, das zeigt auf Basis welcher aktueller Risikostudien der Gen-Mais verboten werden kann. '

zum Gutachten

hier die Zusammenfassung:
Die vorliegende Kurzstudie legt dar, dass ein Anbauverbot von MON810 in Deutschland
wissenschaftlich und rechtlich geboten ist. Sie gibt einen Überblick über die Ergebnisse neuer
wissenschaftlicher Publikationen, die deutlich machen, dass die Risiken des Anbaus von MON810 für
die menschliche Gesundheit und die Umwelt bisher nicht ausreichend untersucht wurden. So liegen
neue, konkrete Hinweise auf eine Gefährdung von Bienen, von nützlichen Insekten und der Ökologie
von Gewässern vor. Auch zur Gefährdung der Gesundheit liegen neue Studien vor, die zeigen, dass
der gentechnisch veränderte Mais dazu beitragen kann, Immunkrankheiten auszulösen.
Zudem wird in der Studie anschaulich gemacht, dass die bisher praktizierten Ansätze zur
Risikobewertung von MON810 zu kurz greifen: Sie setzen sich nicht in angemessener Weise mit der
Sicherheit des Insektengifts auseinander, das in den Gentechnik-Pflanzen produziert wird. Die
wissenschaftliche Unsicherheit über die Wirkungsweise des produzierten Gifts wird differenziert
dargestellt.
Darüber hinaus werden die Argumente einer kritischen Prüfung unterzogen, die vom Bundesamt für
Verbraucherschutz und Lebensmittelsicherheit (BVL) und von der Zentralen Kommission für die
Biologische Sicherheit (ZKBS) im Jahr 2007 als Beweis für die Sicherheit von MON810 vorgebracht
wurden.
Insgesamt wird gezeigt, dass sich seit dem Jahre 2007, als in Deutschland zuletzt über ein
Anbauverbot des gentechnisch veränderten Mais MON810 diskutiert wurde, weitere konkrete
wissenschaftliche Hinweise auf eine Gefährdung von Mensch und Umwelt durch MON810 ergeben
haben. Zudem ist noch deutlicher geworden, dass es erhebliche Lücken bei der Risikobewertung des
Bt-Toxins gibt, das in den MON810-Pflanzen gebildet wird.
Dass ein Verbot des Anbaus von MON810 nicht nur in der Sache, sondern auch rechtlich geboten ist,
wird abschließend anhand dem deutschen und europäischen Gentechnikrecht sowie der
Rechtsprechung belegt.

Colloids, Grains and Dense Suspensions: under Flow and under Arrest

2009-01-22T15:12:00.003+01:00

Announcement

Colloids, Grains and Dense Suspensions: under Flow and under Arrest

2 Day Discussion Meeting – Free International Scientific Conference

9 – 10 March 2009

Location:

The Royal Society

6-9 Carlton House Terrace

London SW1Y 5AG

Organised by

Professor Michael Cates FRS (University of Edinburgh), Dr Paul Bartlett (University of Bristol),

Professor Wilson Poon (University of Edinburgh).

Synopsis

Colloidal suspensions undergo Brownian diffusion that arrests at high density, remobilizing under flow. Slowly sheared non-Brownian particles (dry or in suspension) likewise show chaotic trajectories, but of quite different origin. Both systems can jam spontaneously when too large a stress is applied. This meeting will compare and contrast the flow, jamming and arrest of Brownian and non-Brownian materials.

Chairs

Professor Henk Lekkerkerker, Professor Rudolf Klein

Speakers

Dr Daniel Bonn, Professor Bulbul Chakraborty, Professor Matthias Fuchs, Professor Jennifer Lewis, Professor Narayan Menon, Professor Sidney Nagel, Professor David Pine, Dr Olivier Pouliquen, Professor Peter Pusey FRS, Dr Fahrang Radjai, Dr Veronique Trappe, Professor Dimitris Vlassopoulos

Registration

This meeting is free to attend, but pre-registration (online) is essential. The online registration form and programme information can be found at

royalsociety.org/events

Particulate Systems Analysis 2008 Depletion flocculation characterised by multisample analytical centrifugation

2008-07-17T09:55:00.002+02:00

Particulate Systems Analysis 2008 2-4th September, Stratford-upon-Avon

Paper

Depletion flocculation characterised by multisample analytical centrifugation

T. Sobisch, T. Detloff, D. Lerche

A considerable part of dispersions used in various technical applications show depletion flocculation. Under these circumstances the particle size distribution depends on polymer and particle concentration. Therefore, dilution has to be avoided if the particle size distribution has to be determined. Further, for technical separation processes like centrifugation the effective (apparent) viscosity of the polymer solutions is of interest. As polymer solutions often exhibit shear thinning behaviour the shear dependent apparent viscosity has also to be known for the determination of particle size distribution by analytical centrifugation. The paper describes a new method how one can determine the shear dependent apparent viscosity of polymer solutions in the centrifugal field in-situ using monodispersed particles as tracer. Based on this approach it is then possible to determine the overall particle size distribution of depletion flocculated dispersions and the particle size distribution of particles remaining in suspensions for given times of centrifugation. The approach was successfully applied to the characterization of polydisperse quartz dispersions.

"öffentliches" Gelöbnis vor dem Reichstag

2008-07-13T00:35:00.001+02:00

"öffentliches" Gelöbnis vor dem Reichstag - Schweigen der Grünen bei Benutzung der öffentlichen Grünflächen für Militärritual?

Nach einem Sturm der Entrüstung (Verteidigungsminister - jetziger und ehemalige, Bildzeitung, CDU, FDP) darf sie nun doch stattfinden, die öffentliche Vereidigung unter breitem Ausschluß der Öffentlichkeit, weiträumiger Absperrung - unter Vermittlung des Rot/Roten Senats.

Ursprünglich sollte ja über 4 Tage alles abgesperrt werden, wir sind ja ein demokratischer Rechtsstaat. Protestieren darf man sicher immer, nur da wo es nicht stört. Ein bischen hatte man sich wohl doch bei den Chinesen abgeschaut.

Politikverdrossenheit - hat wohl auch damit zu tun, daß die Staatsreson oben an steht. Ein schwarz-gelber Senat hätte ebenso gehandelt wie jetzt der rot-rote und wohl auch ein rot-grüner!

Bei einer aktuellen Internetrecherche habe ich nur eine Positionierung DER LINKEN gegen den Vorgang gelesen. Gegen die Vereidigung ist jetzt eine Demo angemeldet worden.

Wenn schon öffentliches Gelöbnis, dann auch öffentlich - sonst bitte in der Kaserne. Für mich wird die Demokratie [u]nicht[/u] mit militärischen Mitteln verteidigt und ich bin nicht allein mit dieser Auffassung.

Eine kritische Stellungname der Grünen zum Vorhaben der "öffentlichen" Vereidigung ist überfällig. Von der t.w. antimilitaristischen positionierten Linken kann man das Wohl wegen Rücksichten auf den rot-roten Senat wohl nicht erwarten.

Easing formulation of suspensions by bottom focused back scattering - Poster at SIS2008

2008-06-19T15:55:00.000+02:00

Poster at 17th International Symposium on Surfactants in Solution on August 17-22, 2008 Berlin

Easing formulation of suspensions by bottom focused back scattering

Selection of efficient dispersants, their optimum concentration and processing conditions is a demanding and time consuming process. In almost all cases a high sedimentation stability is required. Evaluation of sedimentation stability can be eased when focusing on the changes in particle concentration right at the bottom part of the suspensions.

A new multisample approach using light backscattering signals is presented. It allows for fast measurement of stability and/or demixing phenomena and separation kinetics of up to 8 different samples simultaneously. The concentration change is measured in a very small region of interest at the bottom of sample cell by light back scattering. The method was applied to trace the optimum dispersant concentrations for mineral suspensions stabilized by nonionic or anionic surfactant. Further the influence of processing conditions and pH was evaluated.

Easing formulation of emulsions by bottom focused back scattering - poster at SIS2008

2008-06-19T15:51:00.000+02:00

Poster at 17th International Symposium on Surfactants in Solution on August 17-22, 2008 Berlin

Easing formulation of emulsions by bottom focused back scattering

Selection of efficient emulsifiers, their optimum concentration and processing conditions is a demanding and time consuming process. In almost all cases a high creaming stability is required. Evaluation of creaming stability can be eased when focusing on the changes in droplet concentration right at the bottom part of the emulsion samples.
A new multisample approach using light backscattering signals is presented. It allows for fast measurement of stability and/or demixing phenomena and separation kinetics of up to 8 different samples simultaneously, by monitoring the concentration change in a very small region of interest at the bottom of sample cell.
The method was applied to trace the optimum emulsifier concentrations for silicone oil emulsions stabilized by nonionic or anionic surfactant. Further the influence of processing time and intensity was evaluated for a high speed rotor stator mixer.

Sedimentation and consolidation behaviour of mineral suspensions flocculated by adsorbing and nonadsorbing polymers - poster at SIS2008

2008-06-19T15:43:00.000+02:00

Poster at 17th International Symposium on Surfactants in Solution on August 17-22, 2008 Berlin

Sedimentation and consolidation behaviour of mineral suspensions flocculated by adsorbing and nonadsorbing polymers

In many industrial applications stability and rheological behaviour of dispersions is adjusted using polymeric additives. Nonadsorbing polymers used as thickeners to stabilise formulations not only increase fluid viscosity but can also induce depletion flocculation. On the other hand adsorbing polymers are used mainly to flocculate suspensions for enhanced separation. Both types of flocculation are concentration dependent, high polymer concentration can lead to restabilization.

In this paper the sedimentation and consolidation behaviour of flocculated polydisperse quartz dispersions were investigated as function of polymer concentration. Depletion flocculation was induced by adding anionic polyacrylamide, electrostatic flocculation by adding a high charge density cationic polymer (PolyDADMAC).
Sedimentation and consolidation behaviour was measured as function of excess pressure applied using a multisample analytical centrifuge. This results in information about dispersion stability, packing density, dewaterability and rheological properties (compressive yield stress, elasticity).
The packing density as function of polymer concentration and centrifugal pressure applied was separately determined by X-ray adsorption. In addition to the average packing density obtained by analytical centrifugation this method allows to determine the local distribution of particle concentration.

A New Method Based on Light Backscattering Signals to trace Sedimentation and Creaming - paper at SIS 2008

2008-06-19T15:37:00.001+02:00

Presentation at 17th International Symposium on Surfactants in Solution on August 17-22, 2008 Berlin

A New Method Based on Light Backscattering Signals to Trace Sedimentation and Creaming

A considerable percentage of industrial products are dispersions (emulsions, suspensions, suspoemulsions). In addition to microbiological and chemical stability, physical stabilities manifested in creaming and/or sedimentation processes are also of great importance, both for the R&D and production process. The increasingly complex demands placed on new formulations require fast, reliable and cost-efficient means for analysing equipments.
A new multisample approach using light backscattering signals is presented. It allows for fast measurement of destabilisation and/or demixing phenomena and separation kinetics of up to 8 different samples simultaneously, by monitoring the concentration change in a very small region of interest at the bottom of sample cell.
The paper deals with the measuring principle and the analysis of the measuring signals. The whole time course can be described by a three parametric function. We represent applications regarding classification of dispersions with different stabilities due to different surfactants or emulsifiers as well as checking of destabilisation procedures.

This study was supported by a grant from the Federal Ministry of Economics and Technology (grant number KA0248303FK6).

Rapid emulsifier selection and evaluation of emulsion stability for reformulation - presentation at SIS2008

2008-06-19T15:28:00.000+02:00

Presentation at 17th International Symposium on Surfactants in Solution on August 17-22, 2008 Berlin

Rapid emulsifier selection and evaluation of emulsion stability for reformulation

Selection of emulsifiers and evaluation of emulsion stability is a frequent task. This relates to practical issues like formulation of emulsions, optimization of preparation conditions, quality control, shelf life estimation and breaking of emulsions. Due to European legislation (REACH) many companies are facing the problem to replace proven components in their formulations (low volume speciality compounds or problematic chemicals). This also applies to emulsifiers and emulsion based products.
A multisample technique based on analytical centrifugation is presented which allows for an accelerated study of creaming, sedimentation and of separation of oil and water phases. Not only information on the extent of phase separation is provided but also the kinetics are measured directly in-situ. The latter is of great practical importance for estimation of shelf life and in relation to the engineering of separation processes.
The method was applied to check for alternatives to nonyl phenol based surfactants as emulsifiers for silicone oil emulsions. Due to the multisample approach one centrifugal run with 12 different samples was sufficient to identify more environmentally benign emulsifiers with identical or better performance. In a second run the efficiency of emulsifier combinations was tested. In addition to these investigations the applicability of the method for selection of the most efficient emulsification conditions was demonstrated.

Farben & Lacke: Schnelle Bewertung von Entmischung und Segregation

2008-06-18T12:20:00.000+02:00

Artikel in Welt der Farben Ausgabe Juli/August 2008

Farben & Lacke: Schnelle Bewertung von Entmischung und Segregation

Titus Sobisch, Dietmar Lerche, Arnold Uhl, L.U.M. GmbH, Rudower Chaussee 29, 12489 Berlin

Problemstellung

Zur Gewährleistung der Kundenzufriedenheit sind folgende Stabilitätsprobleme von Farben und Anstrichstoffen zu vermeiden oder zu minimieren:

· Synerese – an der Oberfläche scheidet sich das Dispersionsmedium ab

· Pigmentsegregation – Änderung der Farbzusammensetzung innerhalb des Behälters

· Partikelsegregation – Änderung der Partikelgrößenzusammensetzung innerhalb des Behälters.

Diese Aufgaben stellen sich sowohl bei der Entwicklung neuer Produkte als auch regelmäßig bei der Qualitätssicherung in der Produktion. Zur Lösung dieses Problems läßt sich die Analytische Zentrifugation mit Mehrprobenrotor einsetzen, wodurch eine bis zu 2300-fach beschleunigte Bewertung der Entmischungsstabilität von Produkten der Farb- und Lackindustrie ermöglicht wird. Durch Einsatz der Zentrifugation werden Entmischungsprozesse und somit die Bewertung der Produkte beschleunigt.

Scope

To assure continued consumer satisfaction the following stability issues of paint products have to be minimized or avoided:

· Syneresis – separation of the liquid dispersion media

· Pigment segregation – change of colour composition inside a container

· Particle segregation – change of particle size distribution inside a container

These stability issues have to be addressed not only during development of new paint products but also for quality assurance during production on a regular basis. This application note demonstrates that multisample analytical centrifugation can be used as an efficient tool for the accelerated evaluation of separation stability of paint products.

In addition this technique provides for high resolution data of particle size distributions of pigments or emulsions.

Campact Klimaappell an Merkel und Gabriel

2008-05-08T09:32:00.000+02:00

Unterzeichnen Sie den Appell an Merkel und Gabriel

Zukunft statt Kohle!

Den Energiekonzernen ist unser Klima egal: Sie wollen mehr als 20 neue Kohlekraftwerke bauen. Für Jahrzehnte würde eine klimaschädliche und ineffiziente Stromproduktion zementiert.

Fordern Sie Angela Merkel und Umweltminister Gabriel auf, die Pläne zu stoppen: Sie müssen neuen Kraftwerken per Gesetz vorschreiben, Energie effizient zu nutzen. Nur wer mindestens 58 Prozent der im Brennstoff enthaltenen Energie zur Stromerzeugung nutzt, darf bauen. Das schaffen moderne Gaskraftwerke, während Kohlekraftwerke scheitern. zur Kurzinfo

Unterzeichnen Sie den Appell! Die Namen aller Unterzeichner/innen werden täglich an Merkel und Gabriel verschickt und bei der Sitzung des Bundeskabinetts zum Klimaschutz am 27. Mai öffentlich präsentiert.

Separation behaviour of suspensions in polymer solutions WFC 10 World Filtration Conference 10

2008-04-21T12:31:00.001+02:00

Contribution to 10th World Filtration Conference April 14-18 2008 Leipzig/Germany
Separation behaviour of suspensions in polymer solutions studied by multisample analytical centrifugation

T. Sobisch*, T. Detloff, D. Lerche

In many industrial applications the separation behaviour of dispersions is influenced by the presence of polymeric additives. For example nonadsorbing polymers used as thickeners to stabilise formulations not only increase fluid viscosity but can also induce depletion flocculation. Both viscosity increase and depletion flocculation will modify separation processes. Furthermore the rheological properties of polymer solutions are generally shear dependent.

In this paper we study the shear dependent sedimentation in a centrifugal field for monodisperse (silica) and polydisperse (quartz) dispersions in anionic polymer solutions of varying concentration.

A multisample analytical centrifugation technique with photometric detection (STEP-Technology) is used in this study to trace the sedimentation velocity, velocity and size distributions in-situ. Measurements with monodisperse silica could be used to determine the effective viscosity as function of polymer concentration and centrifugal acceleration. Results revealed depletion flocculation at low polymer concentration but stabilization at higher concentrations. For the polydisperse quartz dispersions the sedimentation velocity of the coarse fraction and the particle size distribution in the supernatant could be determined.

Keywords

sedimentation, analytical centrifugation, velocity distribution, particle size distribution, polymer solutions, depletion flocculation, in-situ measurement, solid-liquid separation

Evaluation of beverage cloud emulsion stability - Food Colloids 2008

2008-04-21T12:13:00.000+02:00

Contribution to Food Colloids 2008 - Le Mans
Evaluation of traditional and new methods determining beverage cloud emulsion stability
C. Cherbit, S. Reiner, G. Reineccius
Department of Food Science and Nutrition, University of Minnesota, 1334 Eckles Ave., Saint Paul, MN 55108 USA
T. Sobisch, D. Lerche LUM, Berlin, Germany

Emulsions are inherently unstable. This is an ongoing problem for the food and flavor industries. The objective of this work was to evaluate two instruments (LUMiSizer® and LUMiReader®) designed to characterize dispersion stability thereby potentially replacing lengthy and costly traditional methods.
Several beverage cloud emulsions were prepared using orange terpenes or medium chain triglycerides as the oil phase, emulsifiers (gum acacia or a chemically modified starch), in the presence or absence of a weighing agent (ester gum). Results obtained with the analytical centrifuge LUMiSizer® and the separation analyser LUMiReader® were compared to those obtained using traditional methods (visual observations of creaming, measurement of absorbance to obtain the opacity and droplet size index, and particle size analysis).
For the systems investigated application of high resolution photometric detection compared to traditional methods resulted in more detailed information in shorter time.

70 % gegen Bahnprivatisierung

2008-03-28T14:29:00.000+01:00

Repräsentative Emnidumfrage von Bahn für Alle

70 Prozent der Bevölkerung lehnen jede
Kapitalprivatisierung ab und wollen eine Bahn in
öffentlicher Hand. Das hat eine repräsentative Befragung
des Meinungsforschungsinstituts Emnid im Auftrag von "Bahn
für Alle" ergeben. Die Entscheidung über die Zukunft der
Bahn ist für viele Menschen wichtig für ihre künftige
Wahlentscheidung, hat die Umfrage ebenfalls ergeben.

In keiner Partei gibt es eine Mehrheit für eine
Bahnprivatisierung. Unter Anhängern der SPD ist die
Ablehnung mit 73 Prozent besonders hoch.

Die Menschen messen der Zukunft der Bahn eine hohe
Bedeutung bei. Lediglich ein Drittel der Bevölkerung meint,
dass die Haltung der Parteien zur Bahnprivatisierung für
ihre Wahlentscheidung unwichtig sei.

Befragt wurden von Emnid am 25. und 26. März 2008
telefonisch 1006 Personen ab 14 Jahre.

Charakterisierung interpartikulärer Kräfte

2008-03-14T08:43:00.000+01:00

Artikel in

Chemie Ingenieur Technik Volume 80, Issue 3 , Pages 393 - 397

Charakterisierung interpartikulärer Kräfte für Fest/Flüssig-Trennverfahren mittels Analytischer Zentrifugation

T. Sobisch, D. Lerche
Dispersionen • Partikel • Trennverfahren • Zentrifugation

Das Verhalten von Dispersionen, gekennzeichnet durch Entmischungs-, Fließ- und Packungsverhalten, wird durch Art und Stärke der interpartikulären Wechselwirkungskräfte bestimmt. Dies ist von grundlegender Bedeutung für die Anwendung von Dispersionen auf verschiedensten Gebieten aber auch für Fest/Flüssig-Trennverfahren. Der folgende Beitrag berichtet über die Anwendung der Analytischen Zentrifugation zur Untersuchung der Kinetik und Polydispersität von Trennprozessen sowie des Packungs- und Kompressionsverhaltens am Beispiel polydisperser Feinstpartikelsuspensionen. Die Analytische Zentrifuge misst die lokalen und zeitlichen Änderungen der Transmission mittels STEP-Verfahren. Innerhalb der untersuchten Feinstpartikelsuspensionen variiert der Grad der Partikelwechselwirkung von repulsiv bis stark attraktiv und deckt somit den gesamten Bereich typischer Trennaufgaben ab. Die Charakteristik der Trennprozesse (Einzelkorn- oder Zonensedimentation, freie oder behinderte Sedimentation, Konsolidierungsverhalten, Polydispersität) lässt sich aus der Form und dem Verlauf der gemessenen Transmissionsprofile bestimmen. Repulsive Partikelwechselwirkungen führen zu einem polydispersen Sedimentationsverhalten, d. h. die Teilchen sedimentieren mit unterschiedlicher Geschwindigkeit entsprechend ihrer Größe. Im Fall stark attraktiver Wechselwirkungen bewegen sich insbesondere bei hohen Volumenkonzentrationen alle Partikel gemeinsam mit dergleichen Geschwindigkeit. Wenn nur schwache Anziehungskräfte wirken, bildet sich eine Sedimentationsfront, die den Großteil der Partikel einschließt, ein Teil der kleineren Partikel zeigt aber weiterhin polydisperses Sedimentationsverhalten. Die erzielbare Packungsdichte wird gleichfalls durch die Stärke der Partikelwechselwirkungen bestimmt. Aus technologischer Sicht steht die Packungsdichte im direkten Zusammenhang mit der Entwässerbarkeit bzw. dem Entfeuchtungsverhalten sowie der Redispergierbarkeit. Für kolloidchemisch stabile Dispersionen (repulsive Wechselwirkungen) werden auch bei relativ geringer Zentrifugalbeschleunigung hohe Packungsdichten erreicht, die Sedimente sind nahezu inkompressibel. Bei polydispersen Systemen tritt in diesem Fall Partikelsegregation auf. Mit Zunahme der Anziehungskräfte zwischen den Teilchen ist ausgeprägtes Kompressionsverhalten zu beobachten, die Packungsdichte ist stark vom ausgeübten Zentrifugaldruck abhängig. Bei stark geflockten Systemen werden selbst bei sehr hohen Drücken nur moderate Entfeuchtungsgrade erzielt.

Änderung des Gentechnik-Gesetzes beschlossen campact aktion

2008-01-26T21:08:00.000+01:00

Der Bundestag hat die Änderung des Gentechnik-Gesetzes beschlossen / ein Durchmarsch der Agro-Gentechnik findet nicht statt.

Zusammenfassung der neuen Regelungen

Zusammenfassung der überwiegend erfolgreichen Campactaktion seit Anfang 2006.

Campact - Demokratie in Aktion (http://www.campact.de)

Paint products: Accelerated stability and quality testing

2007-11-02T15:34:00.000+01:00

On line article at SpecialChem4coatings.com

Paint products: Accelerated stability and quality testing
Part I: Direct measurement of separation and segregation by multisample analytical centrifugation

Scope

To assure continued consumer satisfaction the following stability issues of paint products have to be minimized or avoided:

syneresis - separation of the liquid dispersion media
Pigment segregation - change of colour composition inside a container
Particle segregation - change of particle size distribution inside a container

In part II the application of multi-sample analytical centrifugation for optimization of deagglomeration of pigment particles will be addressed.

Formula V - Formulation Science and Technology 2007

2007-11-02T14:41:00.000+01:00

Formula V 19 - 22 November Potsdam, Germany

' Formulating opens the way for tailoring products for specific applications and combining components with often contradicting properties. Formulation science and technology is a core discipline for industries and applications like home care, cosmetics, plant protection and coatings but also of emerging importance in fields like electronics, composite materials and biomedical technology.'

Poster contributions

Accelerated screening of formulations towards freeze-thaw stability

T. Sobisch, D. Lerche, L.U.M. GmbH, www.lum-gmbh.com

Rudower Chaussee 29, 12489 Berlin, Germany

The formulation of dispersion based products as well as process development/monitoring and quality assurance require efficient and objective analytical tools for shelf life prediction and stability determination. Freeze/thaw stability is often used as measure of long term stability. On the other hand high freeze/thaw stability is often required as a material property. To this end the potential of multisample analytical centrifugation was evaluated as an accelerated test procedure.
A new multisample approach is presented using analytical centrifugation (STEP-Technology), which allows for an accelerated characterization of destabilization processes (creaming, sedimentation, coalescence, phase separation). The kinetics of these destabilizing processes can be traced simultaneously for up-to 12 different samples with temperature control in the range between 4 and 60 °C.
Analytical centrifugation measures in a rapid way the inherent stability of the samples. Therefore, alterations due to accelerated aging by freeze/thaw cycling can be traced far more earlier than by naked eye.

The wide application potential of this approach is demonstrated by examples of measurements on paints, cosmetics and food products.

Thickener performance traced by multisample analytical centrifugation

T. Sobisch, D. Lerche, L.U.M. GmbH, www.lum-gmbh.com

Rudower Chaussee 29, 12489 Berlin, Germany

Polymeric thickeners are important ingredients to adjust flow properties and stability of formulations. The effect of polymeric additives on dispersion properties is rather complex (viscosity of the continuous phase, adsorption and depletion effects, interaction with other ingredients). Therefore optimum formulation requires extensive experimental investigations.

A new multisample approach is presented using analytical centrifugation (STEP-Technology), which allows for an accelerated characterization of separation stability. Even more, comparing measurements at different centrifugal acceleration information on flow properties is also available (Newtonian, shear thinning or thickening behaviour, yield point, compressive yield stress). The kinetics of separation can be traced simultaneously for up-to 12 different samples with temperature control in the range between 4 and 60 °C.
The potential of multisample analytical centrifugation for formulation design was demonstrated investigating the effect of particle (calcium carbonate, silica) and polymer (polyacryl amide) concentration on dispersion properties of different stabilized suspensions.

making palm oil production less polluting - the wastewater issue

2007-09-28T08:49:00.001+02:00

besides the issue of rain forest destruction conventional palm oil production generates up-to 4 tonnes highly contaminated wastewater and more then 40 cubic meter methane per tonne of palm oil produced.

To reduce environmental impact German researchers have developed a treatment process using wastewater and plant residues of oil production for co composting.

Concerns Over Bisphenol A

2007-09-06T08:45:00.000+02:00

Human exposures are usually as high as those causing profound effects in rodents

"THE SUSPECTED LINK between low levels of human exposure to bisphenol A (BPA), a monomer widely used to make polycarbonate plastic and epoxy resins, and adverse health affects was bolstered last week with the publication of four toxicology studies that investigated the link.

The most significant paper is a consensus statement from 38 scientists released online in Reproductive Toxicology (DOI: 10.1016/j.reprotox.2007.07.005). It concludes that human exposure to BPA, primarily from food containers, is within the range shown to be biologically active in animal studies. In rodents, low BPA exposures in the womb cause increases in the rates of prostate and breast cancer, reproductive abnormalities, lowered sperm counts, early onset of puberty in females, and obesity and insulin-resistant diabetes."

.................
"Despite growing evidence of toxic effects in lab animals, manufacturers of BPA insist that their product is safe. Steven Hentges, executive director of the polycarbonate/BPA group at the American Chemistry Council, an industry group, disputes the new research in Reproductive Toxicology. He says it is not credible, pointing to a European Food Safety Authority report that indicated no adverse effects of BPA"

Risk due to endocrine effect of compounds used in personal care products

2007-08-21T08:46:00.001+02:00

COMMENTARY: Do Personal-Care Products Need a Makeover? (By Gary Ginsberg)

E/The Environmental Magazine - Norwalk,CT,USA
'The typical surfactants, emulsifiers, oils and fragrances are
generally safe. However, as with many things, the devil is in the details
and it's the small ...'

problems associated with phtalates, parabens, benzophenons, bisphenol A, triclosan

What´s Toxic, What´s not

Gefährdungen durch Chemikalien in Bekleidungstextilien - Übersicht

2007-08-08T08:35:00.000+02:00

BfR- Bundesinstitut für Risikobewertung gibt einführende Übersicht über Gefährdungen durch Chemikalien in Bekleidungstextilien

depleted uranium amunition leads to groundwater contamination - Uranmunition im Boden führt zu radioaktiver Grundwasserkontamination

2007-07-05T08:58:00.000+02:00

Langzeitstudie zur Auflösung von Uranmunition im Boden

"In einer bisher einmaligen Langzeitstudie haben Wissenschaftler vom GSF Forschungszentrum für Umwelt und Gesundheit in Kooperation mit dem Forschungszentrum Dresden-Rossendorf (FZD) untersucht, was mit panzerbrechender Uranmunition passiert, die lange im Boden lagert und damit Verwitterungs- und Auswaschungsprozessen ausgesetzt ist. Die Ergebnisse zeigen, dass die Munition schnell zersetzt wird und Uranverbindungen in das Grundwasser gelangen können."

Exposure to depleted uranium (DU) particles strongly increases risk of lung cancer

2007-05-16T08:48:00.000+02:00

The Alchemist Newsletter: May 8, 2007

'Exposure to depleted uranium (DU) particles is a source of growing concern internationally as it increases the risk of lung cancer, according to John Pierce Wise Sr of the University of Southern Maine. Writing in the journal Chemical Research in Toxicology the researchers explain that DU has a density twice that of lead and so is used in military armor and munitions. However, DU dust produced in combat can lead to frequent and widespread exposure of military personnel and civilians during an after combat. Few studies have been undertaken, bit Wise and his colleagues have now tested the effects of DU on cultures of human lung cells. "This is the first report on the cytotoxicity and clastogenicity [chromosome damaging potential] of particulate and soluble DU in human bronchial cells," the researchers say.'

Fast evaluation of dispersion properties for particle size analysis / Charakterisierung der Dispersionseigenschaften für die Partikelgrößenanalyse

2007-04-24T10:39:00.000+02:00

LUMiFuge / LUMiSizer - Application

Evaluation of dispersion properties for particle size analysis

Scope

To obtain reasonable information about the size of particles in powders and suspensions full dispersion of the particles is required prior to particle size measurement. Therefore the question arises how to select dispersion conditions and dispersion media properly. Often not the size distribution of aggregates/agglomerates is of interest but the distribution of the size of primary particles. In this case intense processing and suitable dispersants have to be applied. Multisample analytical centrifugation can be used as an efficient screening tool to assist in sample preparation. Even more it allows for high resolution determination of particle size distributions.

LUMiFuge / LUMiSizer - Anwendungsschrift

Charakterisierung der Dispersionseigenschaften für die Partikelgrößenanalyse

Problemstellung

Sinnvolle Ergebnisse zur Partikelgrößenverteilung von Pulvern und Suspensionen sind nur erhältlich, wenn die Partikel bei der Messung hinreichend gut dispergiert vorliegen. Es ergibt sich die grundsätzliche Frage, wie die experimentellen Dispergierungsbedingungen und das Dispersionsmedium zu wählen sind. In vielen Fällen interessiert nicht die Verteilung der Aggregate sondern die der Primärpartikel. In diesen Fällen müssen die Agglomerate intensiv mechanisch beansprucht und Dispergiermittel eingesetzt werden. Die Analytische Zentrifugation mit Multiprobenrotor läßt sich als effizientes Werkzeug beim Screening der geeigneten Probenvorbereitung einsetzen. Darüber hinaus ermöglicht die Analytische Zentrifugation die Bestimmung der Partikelgrößenverteilungen mit hoher Auflösung.

2007-03-07T14:02:00.000+01:00

Poster presented at the 4th World Congress on Emulsions Lyon 2006

Evaluation of long term stability of model emulsions by multisample analytical centrifugation

T. Sobisch, D. Lerche,

L.U.M. GmbH, Rudower Chaussee 29 (OWZ), 12489 Berlin, Germany,

www.lum-gmbh.com, info@lum-gmbh.de

F. Aguilar, G.G. Badolato, H.P. Schuchmann,

Institute of Engineering in Life Sciences, Department of Food Process Engineering, University of Karlsruhe, Haid-und-Neu-Str. 9, 76131 Karlsruhe, Germany

Abstract

Destabilisation processes in emulsions are very complex. Aging and breaking of emulsions are the result of several processes – creaming or sedimentation, flocculation, coalescence, Ostwald ripening, phase inversion – which can occur separately or simultaneously. This is the main reason why the development of reasonable procedures for shelf life prediction is very difficult and always depends on the product which is subject to evaluation.

Multisample analytical centrifugation with photometric detection (STEP-technology) is a tool for an accelerated characterisation of any demixing processes (creaming, sedimentation, phase separation) as well as for the quantification of time dependent structural alterations (e.g. flocculation, coalescence, Ostwald ripening).
Model emulsions were designed exhibiting creaming, coalescence, flocculation or Ostwald ripening as the dominating mechanism for instability. To answer the question whether multisample analytical centrifugation can be used to predict the long term stability of emulsions results obtained are compared with rheological measurements, particle size analysis by light scattering and common accelerated stability tests like freeze/thaw cycling and storing at 45 °C.

In all cases the creaming (or sedimentation) velocity measured by analytical centrifugation markedly increased during storage induced by increasing salt concentration (flocculation), increasing droplet size (using emulsifier with lower HLB value) or increasing the fraction of clove oil (Ostwald ripening). During a relatively short period of observation only a small part of these alterations could be detected using conventional methods of emulsion characterization.

Method of multisample analytical centrifugation

The multisample analytical centrifuge (LUMiFuge, LUM GmbH, Berlin Germany) used in this study employs the STEP technology, which allows to measure the intensity of the transmitted light as function of time and position over the entire sample length simultaneously (measurement scheme see Figure).

Measurement scheme of the multisample analytical centrifuge with photometric detection. Parallel NIR-light is passed through the sample cells and the distribution of local transmission is recorded at preset time intervals over the entire sample length.

The data are displayed as function of the position within the sample, representing the distance from the centre of rotation. The transmission profiles obtained are representative for the variation of droplet (particle) concentration inside the sample (low transmission means high, high transmission means low droplet concentration).

The progression of the transmission profiles provides information on the kinetics of the separation process and allows particle characterization.

At the same time up to 8 different samples can be analysed simultaneously at constant or variable centrifugal speed up to 2300 g. The separation behaviour of the individual samples can be compared and analysed in detail by tracing the variation in transmission at any part of the sample or by tracing the movement of any phase boundary.

As for a given type of sample cells the position corresponds to a defined sample volume the relationship between the position and the volume can be established by calibration. This allows to directly determine separated phase volumes and to calculate packing densities.

For further details of the application of the method for characterization of emulsions see [1,2,3].

Silicon oil-in-water emulsions with and without induced flocculation

Oil-in-water emulsions φ= 30 %

Sample preparation:

1. 40 % oil / 1% sodium dodecyl sulfate

Process:Microfluidizer® 500 bar

2. Diluted with deionized water or concentrated salt solution to result in 30 % oil and 0, 150 and 300 mM NaCl

Creaming without centrifugation (high salt concentration)

Centrifugation – creaming at 1100 g (low salt concentration)

During the storage time no significant changes in droplet size and viscosity at 0 and 150 mM NaCl
Creaming and water separation clearly visible after the addition of salt (c > 500 mM NaCl)
For small concentration of salt the height of separated water (in a cylinder) not detected or remains constant
The creaming velocity measured by the analytical centrifuge increases during storage, increasing the salt concentration and increasing the temperature
All emulsions were very vulnerable to freeze/thaw cycling

Coalescencing vegetable oil-in-water emulsions –

stabilised with emulsifiers having different polarity

Oil-in-water emulsions j = 30 %

Process:Microfluidizer® 500 bar

Non ionic emulsifier Emulsions

η mPa/s x_3,2 µm

Tween 20, HLB 16.7 3.73 0.66

Tween 80, HLB 15 3.11 0.62

Tween 65, HLB 10.5 3.12 1.35

Centrifugation – creaming at 1100 g

Movement of the position of the interface emulsion –water (distance to the centre of rotation) during centrifugation measured just after preparation of the emulsions.

Already at this stage distinct differences in stability traced due to bigger droplets (Tween 65) or higher viscosity (Tween 20)

During storage no significant changes in droplet size and viscosity

Creaming velocity increase due to bigger droplet sizes with decreasing emulsifier HLB value (more coalescence during production) or lower viscosity

Increased destabilization at higher temperature
Only unstable emulsion vulnerable to freeze-thaw cycling

Ostwald ripening in water-in-oil emulsions

Water-in-oil emulsions j = 30 %

Process:Microfluidizer® 500 bar

Continuous phase mixture clove/vegetable oil viscosity η

Sample 1 50/50 76 mPa/s

Sample 2 75/25 47 mPa/s

Sample 3 25/75 102 mPa/s

Sample 4 0/100 141 mPa/s

Emulsifier: polyglycerol polyricinoleat PGPR 90 – HLB 1

Marked Ostwald Ripening only at mass fraction clove oil > 0.5
Emulsions droplet size and sedimentation velocity increase during storage, however the viscosity remains unchanged
Instability increases increasing the storage temperature
Results of droplet size measurements and sedimentation velocity are in good agreement

Conclusion

The investigations revealed that analytical centrifugation is well suited for accelerated stability testing of emulsions of varying composition and for various types of slow destabilizing mechanisms. Whereas measurements of droplet size distributions and viscosity measurements were not able to always detect the beginning of destabilization, centrifugal analysis enabled to detect instabilities faster and more accurately. The multisample technique therefore is ideally suited for screening purposes in emulsion product development.

Acknowledgement

This study was supported by a grant from the Bundesministerium für Wirtschaft und Technologie (grant number KA 0047301AWZ3).

References

[1] T. Sobisch, D. Lerche, Rapid characterization of emulsions for emulsifier selection, quality control and evaluation of stability using multisample analytical centrifugation

SCI/RSC/SCS conference Cosmetics and Colloids, London 15 February 2005

http://www.soci.org/SCI/groups/col/2005/reports/pdf/gs3257_sob.pdf

[2] T. Sobisch, D. Lerche,

Rapid selection of dispersants and evaluation of emulsion stability by analytical centrifugation

La Rivista Italiana delle Sostanze Grasse 6/2005 308 – 316

[3] T. Sobisch, D. Lerche, 2007

Application of multisample analytical centrifugation for fast evaluation of long term stability and freeze/thaw stability of emulsions

http://docs.google.com/Doc?id=dcvcr5vw_1fqx3hp

PERFLUORIERTE VERBINDUNGEN - Hintergrundpapier Umweltbundesamt

2007-03-07T08:39:00.000+01:00

Zitat:

Perfluorierte Verbindungen sind verstärkt in die öffentliche Diskussion geraten: „Perfluorierte Verbindungen in aller Munde“, „Gift in Pommes“: Unter diesen und ähnlichen Titeln berichten die Medien über Funde in Trinkwasser und Nahrungsmitteln.

.....

Das ist leider nicht alles: Für Umweltschützer ist es ein Problem, dass Perfluorcarbonsäuren und -sulfonsäuren überall verbreitet sind: Sie lassen sich in Flüssen, in den Weltmeeren, in Robben, Nerzen, Füchsen, Eisvögeln und Fischen aus der kanadischen Arktis und selbst in der Leber von Eisbären auf Grönland nachweisen. Besonders bedenklich sind jedoch die weltweiten Nachweise im menschlichen Blut.

Hintergrundpapier Perfluorierte Verbindungen

Pflanzenschutzmittel in der Umwelt - Übersicht

2007-01-10T08:57:00.000+01:00

Pflanzenschutzmittel in der Umwelt

Übersicht des
Bayerischen Landesamtes für Umwelt
Infozentrum UmweltWissen

'Pflanzenschutzmittel bekämpfen Pflanzenkrankheiten. Leider wirken sie aber nicht nur gegen die
Schaderreger, sondern oft auch gegen andere Lebewesen. Mittlerweile kann man Spuren von
Pflanzenschutzmitteln fast überall nachweisen: im Boden, im Wasser, in der Luft, in unseren Lebensmitteln,
aber auch im Fett der arktischen Eisbären und im Eis der Zugspitze. Aus Umweltsicht
ist daher jede Maßnahme wichtig, die die Anwendung von Pflanzenschutzmitteln reduzieren hilft.
In dieser Publikation finden Sie einen einführenden Überblick über dieses weite Themenfeld.'

PARTEC 2007 conference papers

2007-01-05T14:07:00.000+01:00

PARTEC 2007
Nuremberg, Germany 27-29.3.2007
International Congress on Particle Technology together with POWTECH 2007 / TechnoPharm 2007

Tandem Lecture

Particle interactions in dispersions of micro and nanoparticles / Sedimentation of Colloidal Particles

T. Sobisch1), D. Lerche1), F. Babick 2), G. Salinas Salas 3)

¹⁾ L.U.M. GmbH, Germany, 2)TU Dresden, Germany, 3) Universidad de Talca, Chile

ABSTRACT

The behaviour of dispersions in liquid media, i.e. dispersion stability, flow, separation and packing behaviour, is determined by interparticle forces. This is of fundamental importance for their application in diverse fields such as nanomaterials, coating, paper making, ceramics, sludge dewatering, to name just a few. The first part of the present work reports on the use of multisample analytical centrifugation for investigation of the sedimentation kinetics and the packing and compression behaviour to characterize the colloidal stability and microstructure in aqueous dispersed systems for two different fields of great practical importance, namely mineral particle suspensions and pigment dispersions. The second part focuses on the effect of non-hydrodynamic interactions on the sedimentation behaviour of colloidal systems in liquid media. In many situations complex dependencies prevent a priori calculation of sedimentation kinetics. An experimental study on the influence of double layer interactions on the sedimentation velocity will be presented.
The new multisample approach uses the STEP-technology. Space and time resolved extinction profiles quantify the alteration of particle concentration and packing behaviour without the need for sample dilution. The latter is a necessary prerequisite for ensuring that the liquid dispersions maintain their original properties. The multisample technique applied implies the potential for more systematic studies for targeted colloidal stability.

Introduction

The behaviour of dispersions in liquid media, i.e. dispersion stability, flow, separation and packing behaviour, is determined by the nature and degree of interparticle forces. This is of fundamental importance for their application in diverse fields but also for solid-liquid separation processes. For the characterisation of dispersions analytical techniques are preferable, which avoid sample dilution, thus leaving the dispersion properties unchanged. To this end analytical centrifugation has proven as an efficient tool [1-5] for the quantification of particle porosity [6], particle interaction and particle aggregation [7-11] from both, sedimentation kinetics and packing behaviour.

The first part of the present work reports on the use of multisample analytical centrifugation for investigating the sedimentation kinetics, the packing and compression behaviour with regard to the colloidal stability and microstructure in aqueous dispersed systems.
The sedimentation of stabilised suspensions strongly depends on the particle concentration. Even for dilute systems the decrease in the settling velocity compared to that of isolated particles is quite significant. This is primarily due to hydrodynamic interactions (HI), which are long-range interaction, since disturbances in the flow field decline reciprocally with the distance from the surface. The sedimentation of colloidal particles is additionally affected by the electric double layer surrounding them. The double layer leads to electroviscous effects as well as to electrostatic repulsion between neighbouring particles. Both phenomena can amplify the hydrodynamic hindrance to considerable extent. The second part of our paper presents an experimental study on the influence of double layer thickness on the sedimentation of charged colloidal particles. Investigations were carried out using multisample analytical centrifugation, in which the sedimentation velocity of monosized silica particles was studied at different particle concentration and varying ionic strengths. The results are discussed with regard to the applicability of theoretical models and (semi-)emiprical approximations.

REFERENCES:

[1] R. Buscall, Colloids Surfaces 5 (1982) 269–283.
[2] T. Gilányi, G. Horváth-Szabó, E. Wolfram, J. Colloid Interface Sci. 98 (1984) 72–77.
[3] E. Tombácz, I. Deér, I. Dékány, Colloids Surfaces A 71 (1993) 269-276.
[4] E. Tombácz, B. Horváth, I. Ábrahám, Colloids Surfaces A 71 (1993) 277–285.
[5] S. Tcholakova, N.D. Denkov, I.B. Ivanov, B. Campbell, Langmuir 18 (2002) 8960-8971.
[6] T. Sobisch, D. Lerche, S. Fischer, C. Fanter, Progr. Colloid Polym. Sci. 133 (2006) 169-172. [7] T. Sobisch, D. Lerche, Tenside Surf. Det. 39 (2002) 232-236.
[8] T. Sobisch, D. Lerche, Chemistry Preprint Archive 2002 (2002) 9, 170-184.
[9] T. Sobisch, D. Lerche, In: U. Teipel (Hrsg.): Symposium Produktgestaltung in der Partikeltechnologie Band 2 (2004) 433-448.
[10] T. Sobisch, D. Lerche, Chemistry Preprint Archive 2003 (2003) 7, 198-218.
[11] T. Sobisch, D. Lerche, T. Detloff, M. Beiser, A. Erk, Filtration 6 (2006) 313-321.
[12] D. Lerche, J. Dispersion Sci. Technol. 23 (2002) 699–709.
[13] T. Sobisch, D. Lerche, Colloid and Polymer Science 278 (2000) 369–374.
[14] T. Sobisch, D. Lerche, Filtration 4 (2004) 270 – 274.
[15] G.K. Batchelor, J. Fluid Mech. 52 (1972) 245.
[16] J Happel, H Brenner. Low Reynolds Number hydrodynamics. Nijhoff, The Hague, 1983. [17] DME Thies-Weesie, AP Philipse, G Nägele, B Mandl, R Klein. J. Colloid Interface Sci. 176 (1995) 43-54.
[18] JF Richardson, WN Zaki. Trans. Instn. Chem. Engrs 32 (1954) 35-53
[19] M Smoluchowski, in : Handbuch der Elektrizität und des Magnetismus, Bd.2, Leipzig 1914. [20] Levine S. et al. J. Colloid Interface Sci. 57 (1976) 3, 424-437
[21] Keh & Ding. J. Colloid Interface Sci. 227 (2000) 540-552

paper Ostwald-Kolloquium
27.3. 2007 17.10

Characterization of liquid nanoparticle dispersions by multisample analytical centrifugation

T. Sobisch, D. Lerche

L.U.M. GmbH, Rudower Chaussee 29 (OWZ), 12489 Berlin, Germany, www.lum-gmbh.com

ABSTRACT

Reducing particle dimensions to nanoscale leads to qualitatively new properties. This holds also for liquid dispersions, which are the most often used form of application of nanoparticles. For characterization of nanoparticle dispersions techniques are preferable, which avoid dilution, thus don’t modify dispersion properties. To this end multisample analytical centrifugation proved as an efficient tool. The new multisample approach uses the STEP-technology. Space and time resolved extinction profiles quantify the alteration of particle concentration but also packing behaviour and phase separation during centrifugation.

Examples are presented for examination of colloidal crystallization and of microgels. The effect of initial volume concentration and sediment pressure on the speed and extend of the crystallization process was studied. Further, the behaviour of microgels was characterized as function of centrifugal acceleration, temperature and concentration.

1 Introduction

Application of nanoparticles in diverse fields is fast developing. For practical applications the colloidal stability of nanoparticle dispersions and the particle size distribution is of paramount importance. This relates to the need for a high through-put tool for the analysis of the dispersion properties during formulation, selection of processing conditions and for quality control of manufactured batches. Analytical control over the dispersion properties at various stages is considered as a key to the successful application of nanoparticles. The phase behaviour of nanoparticle dispersions and the phenomenon of colloidal crystallization is closely related to the nature of particle interactions and particle polydispersity, i.e. colloidal crystallization is favoured by a low degree of particle aggregation and low polydispersity of particle size.
Colloidal crystallization has received considerable attention both from a theoretical and an experimental perspective [1 - 6]. Appearance of crystallization in colloidal suspensions has been deduced so far from visual inspection of Bragg Reflections [3-6]. In case of nanosized materials optical detection with high resolution of the local position offers an alternative approach [7]. Microgel particles are often applied as a physical model for soft deformable particles, for the study of rheological properties and phase transitions. Aqueous microgel suspensions are characterized by a strong dependence of particle size on temperature tuneable by the degree of cross linking. Relating to their specific tuneable properties microgel particles have wide ranging potential applications in the field of sensors, catalysis and controlled drug release. Physicochemical characterization of suspension behaviour and thermal and mechanical properties of these materials is essential for quality control and technical applications.
The paper describes the application of multisample analytical centrifugation for qualitative and quantitative characterization of nanoparticle suspensions and microgel particles as function of concentration, temperature and centrifugal pressure applied. The method allows tracing the distribution of light transmission over the whole sample length during centrifugation. Thereby the kinetics and extent of separation processes can be investigated in-situ.

REFERENCES:

[1] M.D. Rintoul, S. Torquato, Physical Review Letters 77 (1996) 4198.

[2] http://www.icmm.csic.es/cefe

[3] A. Imhof, J.K.G. Dhont, Physical Review Letters 75 (1995) 1662.

[4] W.K. Kegel, Langmuir 16 (2000) 939.

[5] K. Yoshinaga, M. Chiyoda, H. Ishiki, T. Okubo, Colloids and Surfaces A 204 (2002) 285.

[6] A.P. Philipse, G.H. Koenderink, Adv. Coll. Interface Sci. 100-102 (2002) 613.

[7] T. Sobisch, D. Lerche, Interaction between tailored particle interfaces characterized by analytical centrifugation,

Chemistry Preprint Archive, Volume 2003, Issue 7, July 2003, Pages 198-218

http://www.sciencedirect.com/preprintarchive,

[8] T. Sobisch, D. Lerche, Application of a new separation analyzer for the characterization of dispersions stabilized with clay derivatives, Colloid and Polymer Science 278 (2000) 369–374.

[9] D. Lerche, Dispersion stability and particle characterisation by sedimentation kinetics in a centrifugal field, J. Dispersion Sci. Technol. 23 (2002) 699–709.

[10] T. Sobisch, D. Lerche, Use of analytical centrifugation for evaluation of solid-liquid separation in decanter centrifuges: Application for selection of flocculants for sludge dewatering, Filtration 4 (2004) 270–274.

[11] T. Sobisch, D. Lerche, T. Detloff, M. Beiser, A. Erk, Tracing the centrifugal separation of fine particle slurries by analytical centrifugation, Filtration 6 (2006) 313-321.

posters

Characterization of carbon black dispersions by multisample analytical centrifugation

T. Sobisch, D. Lerche, N. Quintas, T. Detloff
L.U.M. GmbH, Rudower Chaussee 29 (OWZ), 12489 Berlin, Germany, www.lum-gmbh.com

ABSTRACT

Carbon black dispersions are widely applied in inks and paints. A high dispersity and high degree of dispersion stability is of paramount importance. Analytical centrifugation with photometric detection revealed a surprising phenomenon in several industrial application labs, the so called ‘Backfolding’. After a distinct time of centrifugation a marked reduction in turbidity is observed in the supernatant, separated so far. A close correlation was suspected between the degree of the ‘Backfolding’ and product performance. A detailed investigation of this phenomenon was performed in the centrifugal field as function of preparation conditions of carbon black dispersions, volume fraction, centrifugal acceleration, temperature, viscosity and additives.

Analytical centrifugation can be used for an integral characterization of dispersion quality influenced by viscosity, density difference, particle stabilization and particle size distribution. The new multisample approach uses the STEP-technology. Space and time resolved extinction profiles quantify the alteration of particle concentration and packing behaviour during centrifugation without the need for sample dilution. The latter is a necessary prerequisite for ensuring that the liquid dispersions maintain their original properties. The multisample technique applied implies the potential for systematic studies for targeted colloidal stability.

Separation behaviour and dispersion properties of clay suspensions traced by multisample analytical centrifugation

T. Sobisch, D. Lerche

Clay minerals are used in diverse fields, mostly as rheological additives or for adsorption purposes. The properties of clay suspensions strongly depend on processing and suspension composition. The separation behaviour in the centrifugal field in turn is determined by the dispersion degree obtained and on particle interactions. Therefore analytical centrifugation can be used for optimization of separation/classification after processing and for process development and quality control as well.

Investigations using multisample analytical centrifugation with photometric detection (STEP-technology) are presented.

Depending on dispersion quality a characteristic separation behaviour is observed during centrifugation of clay dispersions. Due to attractive particle interactions usually zone sedimentation is observed. Addition of dispersants might result in polydisperse sedimentation of individual particles (colloidal stable dispersions). Packing behaviour and dewaterability are also directly related to particle interactions and to the degree of delamination. Increasing the degree of delamination the effective volume concentration increases (packing density decreases) Adding efficient dispersants packing density increases due to reduction of attractive particle interactions.

The influence of the duration of dispersion, dispersion intensity and dispersants on degree of delamination, particle interactions, separation behaviour and particle size distributions was exemplified for sepiolites of different origin.

Evaluation of Particle Size Analysis by Novel
Centrifugal Sedimentation Method

T. Detloff1), D. Lerche

1)L.U.M. GmbH, Rudower Chaussee 29, 12489 Berlin, Germany, www.lum-gmbh.com, info@lum-gmbh.de

The particle size distribution of dispersions of fine particles were determined by a multisample analytical photocentrifuge LUMiSizer®, which allows to determine space and time resolved extinction profiles (STEP-Technology) during the centrifugation of up to 12 samples simultaneously. While the variation of the light extinction curves caused by centrifugal segregation allows a qualitative description, a rigorous formulation can give access to detailed quantitative characterization. It will be shown that the particle size distribution may be derived by two procedures: analyzing the variation of the extinction at any point of the sample over centrifugation time or analyzing the extinction variation over the entire sample length at any time of centrifugation. For higher concentrations multiple light scattering and the corresponding flux density function were taken into account.

Furthermore we report on studies regarding the validation of this new approach. In these respect measurements with different “well known” and certified particles where done to proof the accuracy of the PSD of concentrated and diluted dispersions. The sensitivity regarding different monomodal and polymodal particle samples will be demonstrated.

Contact person: Torsten Detloff, L.U.M. GmbH, Rudower Chaussee 29, Germany, phone: +49‑(0)‑30‑67 80 60 30, fax: +49‑(0)‑30‑67 80 60 58, t.detloff@lum-gmbh.de

A Novel Simulation Method for Separation Processes in Gravitational and Centrifugal Field

T. Detloff1), D. Lerche

1)L.U.M. GmbH, Rudower Chaussee 29, 12489 Berlin, Germany, www.lum-gmbh.com, info@lum-gmbh.de

Separation processes and dewatering/deliquoring are of great importance across a variety of industries and have a great number of applications (e.g. waste water treatment mineral processing, geotechnical engineering, industrial sludge or bio-, food and pharma separation). Therefore the sedimentation/flotation behaviour of diluted and concentrated dispersions plays a key role. The Simulation of these processes is more and more important because of the time and cost saving factor. During decades since the pioneering work of Kynch in 1952 [1] different investigations were done to model the separation process of concentrated dispersions driven by gravity or a centrifugal field [2]. Also models for polydisperse dispersions which may be flocculated or forming compressible sediments were developed [3].

Based on these work, the authors will present a software tool to simulate the separation process of mono- and polydisperse dispersions (suspensions and emulsions), including flocculation and sediment compressibility in different container geometries. The simulation results will be compared with conducted experiments using space and time depended concentration detection in gravitational and centrifugal field.

References:

[1] G. J. Kynch, A theory of sedimentation. Trans. Faraday Soc. 48 (1952) 166-176.

[2] G. Anestis, W. Schneider, Application of Theory of Kinematic Waves to Centrifugation of Suspensions, Ingenieur-Archiv 53 (1983) 399-407.

[3] S. Berres, R. Bürger, On gravity and centrifugal settling of polydisperse suspensions forming compressible sediments, Int. J. Solids Structures 40 (2003) 4965-4987.

Filtech 2007 conference papers

2007-01-05T13:49:00.000+01:00

Filtech 2007 International conference & exhibitition for filtration and separation technology
February 27 - March 1, 2007
Wiesbaden Germany

paper

Characterization of interparticle forces for solid-liquid separation processes using multisample analytical centrifugation

T. Sobisch, D. Lerche

Dispersion Stability & Particle Analysis, L.U.M. GmbH

Rudower Chaussee 29 (OWZ), 12489 Berlin, Germany

info@lum-gmbh.de, www.lum-gmbh.com

ABSTRACT

The present work reports on the use of multisample analytical centrifugation for investigation of the kinetics and polydispersity of the sedimentation process as well as of the packing and compression behaviour. The method was applied for two different systems of practical importance, namely, polydisperse fine particle suspensions with varying degree of interparticle attraction and for pigment dispersions modified by milling.

The shape and evolution of these extinction profiles allow conclusions about the nature of the sedimentation process (free sedimentation of individual particles, hindered settling, zone sedimentation). Strong repulsive particle interactions lead to a polydisperse sedimentation behaviour, i.e. particles move with different sedimentation velocities according to their particle size. In case of strong attractive particle interactions all particles are moving with identical velocity. If only weak attractive forces act between the particles a sedimentation front of the main fraction of particles evolves, however, a part of the fine fraction still exhibits polydisperse sedimentation behaviour.

Packing density, obtained after compression, is related to the total interparticle potential energy. The packing behaviour further is directly related to the dewatering (deliquoring) behaviour of the sediment. For colloidal stable dispersions the equilibrium packing density is reached almost instantaneously after applying the centrifugal force and a virtually incompressible sediment is formed. For polydisperse suspensions segregation will occur especially at lower initial volume fractions. Increasing the degree of interparticle forces a pronounced compressional behaviour was experienced, packing density becomes very sensitive to changes in centrifugal pressure. However, for strongly flocculated particle dispersions even at high centrifugal pressures only moderate deliquoring can be achieved.

The sedimentation of pigment dispersions investigated is characterized by zone sedimentation. Packing density increases markedly as deagglomeration proceeds during wet milling. Sedimentation analysis allows for direct measurement of the dispersion degree without dilution.

KEYWORDS

Physicochemical aspects, centrifugation, particle interactions and characterization, solid-liquid separation, clarification, classification, dewatering

Introduction

For characterization of dispersions techniques are preferable, which avoid dilution, thus don’t modify dispersion properties. To this end analytical centrifugation proved as an efficient tool [1-5]. Both, sedimentation kinetics and packing behaviour cover information on particle porosity [6], particle interaction and particle aggregation [7-11]. Fig. 1 shows a schematic overview of the relations between the nature of particle interactions and the sedimentation/packing behaviour.

Fig.1 Schematic overview of relations between the nature of particle interactions and sedimentation/packing behaviour

If strongly repulsive interparticle forces dominate, in dilute systems particles are fully dispersed and sediment individually (colloidal stable dispersions). As the centrifugal acceleration increases with the distance from the centre of rotation sedimentation speeds up until the final sediment height is reached and dense packing is obtained. In case of weakly attractive interactions particles are weakly flocculated. As long as individual flocs sediment the shape of sedimentation curves is similar to that of colloidal stable dispersions. However after formation of a space filling network sedimentation gradually slows down until the centrifugal pressure cannot compress the dense network further (consolidation). Strongly attractive interactions cause strong flocculation. Large flocs sediment very fast and form loose irregular particle networks, which show high resistance against consolidation. The final sediment height is reached only slowly.

paper

Comparison of particle separation in centrifuges with cylindrical tubes or disc rotors .
Experiments and theoretical models

Dietmar Lerche and Torsten Detloff

Dispersion Stability & Particle Analysis, L.U.M. GmbH

Rudower Chaussee 31, 12489 Berlin, Germany

info@lum-gmbh.de, www.lum-gmbh.com

ABSTRACT

Separation and purification of nano- and microparticles becomes essential for technical applications in manifold industrial fields such as biotechnology, drug development, coating and pigment to name only a few. Despite numerous papers since the pioneering work of Kynch, the separation process of concentrated dispersions driven by gravity or a centrifugal field, are not completely understood yet, especially, if particles interact with each other. In the centrifugal case additional difficulties emerge from the Coriolis coupling between the radial and the azimuthal velocity and the geometry of the "containers". Batch centrifuges operate either with containers of constant cross section (CCS geometry) or with disc/cylindrical rotors, where the cross sectional area changes with the distance from the axis of rotation (CSAC geometry). In this paper we shall focus on the sedimentation in these different cell geometries. Experimentally the separation process of dispersions of monodisperse silica and polydisperse quartz at different volume concentrations was investigated by analytical centrifugation (LUMiSizer®). Space and time resolved extinction profiles (STEP-Technology) during the centrifugation were measured using cells with CCS or CSAC geometries. In general, the sediment height in the CSAC cells is smaller compared to CCS ones, but the alteration of the concentration in the vicinity along the radius is similar for both cell types. Experiments were compared with model calculations based on the kinematic Kynch model advanced by Buerger. It will be shown that from results of tube centrifugation (CCS cells) the sedimentation behavior in a disk or cylinder centrifuge (CSAC cells) may be well predicted. This allows to use analytical tube centrifugation to optimize the separation and purification processes of nano- and microparticles by industrial cylinder.

KEYWORDS: Analytical centrifugation, Separation behaviour, Silica, Quartz, Container Geometry, Kinematic Model

Application of multisample analytical centrifugation for fast evaluation of long term stability and freeze/thaw stability of emulsions

2007-01-02T13:55:00.000+01:00

Contribution to the 4th World Congress on Emulsions Lyon 2006

Application of multisample analytical centrifugation for fast evaluation of long term stability and freeze/thaw stability of emulsions

T. Sobisch, D. Lerche

L.U.M. GmbH, Rudower Chaussee 29 (OWZ), 12489 Berlin, Germany

www.lum-gmbh.com, info@lum-gmbh.de

The development of emulsion based products as well as process development/monitoring and quality assurance require efficient and objective analytical tools for shelf life prediction and stability determination. Freeze/thaw stability is often used as measure of long term stability. On the other hand high freeze/thaw stability is often required as property of the final product. To this end the potential of multisample analytical centrifugation was evaluated as an accelerated test procedure.

A new multisample approach is presented using analytical centrifugation, which allows for an accelerated characterization of destabilization processes (creaming, sedimentation, coalescence, phase separation). The kinetics of these destabilizing processes can be traced simultaneously for up-to 12 different samples with temperature control in the range between 4 and 45 °C. No dilution is necessary, which otherwise could lead to changes of dispersion properties.

Analytical centrifugation measures in a rapid way the inherent stability of the samples. Therefore, alterations due to slow aging may be investigated combining first a shorted common accelerated stability test like freeze/thaw cycling and second a rapid evaluation by analytical centrifugation.

The wide application potential of this approach is demonstrated by examples of measurements on cosmetic creams and on beverages.

1 Introduction

Multisample analytical centrifugation is efficient in characterization and measurement of the speed of destabilizing processes like creaming, coalescence and phase separation (1-7). It detects very small differences in stability and allows for an accelerated characterization of emulsions without dilution, thus avoiding changes of emulsion properties.

As a demonstration the evaluation of aging of cosmetic creams and of beverages is presented, which is important in relation to development of new formulations and in quality control of manufactured products. The stability of samples aged during storage at ambient conditions or by a freeze-thaw cycle (accelerated aging) was compared with the initial stability just after manufacturing.

Full article

Application of multisample analytical centrifugation for fast evaluation of long term stability and freeze/thaw stability of emulsions

2007-01-02T13:49:00.000+01:00

http://www.AppliedColloidsSurfactants.info, http://AppliedColloidsSurfactants.blogspot.com, mailto:AppliedColloidsSurfactants@gmail.com

Contribution to the 4th World Congress on Emulsions Lyon 2006

Application of multisample analytical centrifugation for fast evaluation of long term stability and freeze/thaw stability of emulsions

T. Sobisch, D. Lerche

L.U.M. GmbH, Rudower Chaussee 29 (OWZ), 12489 Berlin, Germany

www.lum-gmbh.com, info@lum-gmbh.de

The wide application potential of this approach is demonstrated by examples of measurements on cosmetic creams and on beverages.

1 Introduction

Analytical centrifugation traces the inherent stability, but cannot foresee destabilizing processes that will happen during storage of the sample. But, it will see the results of destabilizing processes far faster than visual observation. Therefore, to this end a combination with suitable stress tests is the method of choice. As a demonstration the evaluation of aging of cosmetic creams and of beverages is presented, which is important in relation to development of new formulations and in quality control of manufactured products. The stability of samples aged during storage at ambient conditions or by a freeze-thaw cycle (accelerated aging) was compared with the initial stability just after manufacturing.

2 Experimental

2.1 Materials and sample preparation
Two different commercial cosmetic o/w creams and two emulsion based beverage samples were used as received close to the date of production, after storage under ambient laboratory conditions over 2 month (cosmetic creams) and after one freeze/thaw cycle (24 h at -10 °C followed by 24 h at 25 °C).

2.2 Method of multisample analytical centrifugation

The multisample analytical centrifuge (LUMiFuge, LUM GmbH, Berlin Germany) used in this study employs the STEP-Technology, which allows to measure the intensity of the transmitted light as function of time and position over the entire sample length simultaneously (Measurement scheme see Fig. 1).

Fig. 1 Measurement scheme of the multisample analytical photocentrifuge. Parallel NIR-light is passed through the sample cells and the distribution of local transmission is recorded at preset time intervals over the entire sample length

The data are displayed as function of the position within the sample, as distance from the centre of rotation (transmission profiles, see Fig. 2). The progression of the transmission profiles contains the information on the kinetics of the separation process and allows particle characterization.

As for a given type of sample cells the position corresponds to a defined sample volume the relationship position – volume can be established by calibration.
For further details of the application of the method for characterization of emulsions see (1-7).

3 Results and Discussion

Fig. 2 Centrifugation of a cosmetic cream of the o/w type at 1100 g for 18 hours. Evolution of transmission profiles with time – first recorded profile undermost (red), last profile uppermost (green).

Figure 2 displays the transmission profiles obtained by centrifugation at 1100 g for the least stable cream analysed after just being manufactured.

The sharp drop in transmission at about 88.5 mm marks the filling height of the sample. The lowest transmission belongs to the first profile (lowest transmission). The destabilizing process, separation of an aqueous phase, starts from the bottom of the cell. The boundary water -emulsion is moving upwards (last profile highest transmission in the bottom region). That is, the separation process is characterized by creaming of oil droplets inside the continuous aqueous phase. From this it becomes obvious that the cream is an oil-in-water emulsion. The type of emulsion oil-in-water (o/w) or water-in-oil (w/o) can easily be deduced from the primary process of destabilization traced by the evolution of transmission profiles – creaming of oil droplets or sedimentation of water droplets.

It has to be noted that the cream has a high inherent stability, given the long time and high speed of centrifugation necessary to produce these changes.

The more stable creams exhibited only a small increase of transmission near the cell bottom. For a comparative investigation therefore the change in transmission of the bottom region was chosen as a measure of stability.

Fig. 3 Change of integral transmission (113 – 114 mm) during centrifugation at 1100 x g for 18 hours – effect of 2 month aging at ambient temperature

Figure 3 shows the effect of two month of aging at ambient temperature for the most and for the least stable sample. The just prepared samples show a distinct less pronounced demixing during centrifugation than the samples after 2 month aging at ambient laboratory conditions. The most likely cause is slow flocculation, which lead to a (temporary) stabilization against creaming due to an increase in viscosity. However, further flocculation is expected to cause irreversible destabilization. In contrast other aging processes like coalescence and Ostwald ripening would have led to a direct destabilization.

The effect of accelerated aging by a freeze-thaw cycle (thawing after storage at -10 °C, for 24 hours compared to the samples not subjected to the freeze-thaw cycle) is depicted in Fig. 4. It is readily obvious from this comparison that aging by one freeze-thaw cycle markedly enhances the differences in stability already inherent in the samples before freezing. As seen the separation of the continuous phase at the bottom is initially slow and speeds up only after a prolonged time of centrifugation. This indicates a stabilizing barrier against creaming (probably a flocculated network). The freeze-thaw cycle obviously reduces the stabilizing barrier causing a marked decrease of the induction period time.

In the case investigated the order of stability of the different creams does not change during aging (2 month, or after an additional freeze-thaw cycle), i.e. the inherent stability of the samples as prepared is altered during aging for all samples the same way. To trace slow destabilizing processes a combination with common accelerated aging tests is the method of choice.

Fig. 4 Change of integral transmission (113 – 114 mm) during centrifugation at 1100 x g for 18 hours – effect of a freeze-thaw cycle after 2 month aging at ambient temperature

Evaluation of long term stability is often complicated by slow diffusion based destabilization processes, which cannot be foreseen by analytical centrifugation. However, the result of these processes can be traced far more faster then by naked eye. An example is given in Fig. 5 for emulsion based beverage samples. In this case the stability was measured by the variation of turbidity during centrifugation. As can be seen the fresh samples exhibited a similar behaviour. However, they were markedly destabilized after only one freeze-thaw cycle. After this, sample 1 showed a substantial higher loss of stability. The same trends were observed after 6 week of storage but less pronounced.

Fig. 5 Effect of aging on emulsion based beverages, influence of 1 freeze-thaw cycle on speed of clarification measured as variation in transmission, centrifugation at 1100 g

4 Conclusions

The investigations revealed that analytical centrifugation was well suited for accelerated stability testing of commercial emulsions in case of slow destabilizing mechanisms. In one case analytical centrifugation traced differences in separation stability just after manufacturing, which were enhanced during only one freeze-thaw cycle. In the other case differences in stability were revealed after freeze-cycling only.

The multisample technique is ideally suited for screening purposes.

5 References

(1) T. Sobisch, D. Lerche, Rapid emulsifier selection and evaluation of emulsion stability by multisample analytical centrifugation, this conference - Topic: - 3 Behaviour, characterization and processing, Workshop: 3.1 New techniques of characterization

(2) T. Sobisch, D. Lerche, G.G. Badolato, F. Aguilar, H.P. Schuchmann, Evaluation of long term stability of model emulsions by multisample analytical centrifugation, this conference:

Topic: - 3 Behaviour, characterization and processing, Workshop: 3.1 New techniques’ of characterization

(3) D. Lerche, T. Sobisch, S. Küchler, Shelf life prediction of emulsions by based on multisample analytical centrifugation, this conference - Topic: - 3 Behaviour, characterization and processing, Workshop: 3.1 New techniques of characterization

(4) T. Sobisch, D. Lerche, Rapid characterization of emulsions for emulsifier selection, quality control and evaluation of stability using multisample analytical centrifugation, 2005,

SCI/RSC/SCS conference Cosmetics and Colloids, London 15 February 2005

http://www.soci.org/SCI/groups/col/2005/reports/pdf/gs3257_sob.pdf

(5) T. Sobisch, D. Lerche, Rapid selection of dispersants and evaluation of emulsion stability by analytical centrifugation, La Rivista Italiana delle Sostanze Grasse 82 (2005) 304 – 312

(6) T. Sobisch, D. Lerche, S. Küchler, A. Uhl, Rapid stability assessment for liquid and paste like foods by multisample analytical centrifugation, Paper Proceedings Euro Food Chem XIII, Macromolecules and their degradation products in food – physiological, analytical and technological aspects, Hamburg, Germany, September 19 – 23 2005, Eds. T. Eklund, M. Schwarz, H. Steinhart, H.-P. Their, P. Winterhalter, pp. 672 – 675, Gesellschaft Deutscher Chemiker e.V., 2005, ISBN 3-936028-31-1

(7) D. Lerche, T. Sobisch, S. Küchler, 2002, Stability analyser LUMiFuge 116 for rapid evaluation of emulsion stability and demulsifier selection, Chemistry Preprint Archive, Volume 2002, Issue 6, June 2002, Pages 195-201 http://www.sciencedirect.com/preprintarchive

EU-Kommission und Vattenfall stellen Gewinnmaximierung über Naturschutz

2006-11-28T09:37:00.000+01:00

ROBIN WOOD - Presse 27.11.06

Lacomaer Teiche dürfen nicht zu Gunsten der klimaschädlichen Braunkohleverstromung abgebaggert werden!
ROBIN WOOD kritisiert die heute bekannt gewordene Stellungnahme der EU-Kommission, in der die Abbaggerung der schützenswerten Lacomaer Teiche genehmigt wird, auf schärfste. Entgegen der Auffassung der EU-Kommission sieht ROBIN WOOD kein übergeordnetes öffentliches Interesse darin, ein gemeldetes Fauna-Flora-Habitat-Gebiet zugunsten der klimaschädlichen Braunkohleverstromung zu vernichten. ROBIN WOOD fordert das Land Brandenburg auf, die Interessen des Konzerns Vattenfall nicht höher zu bewerten, als die Interessen des Natur- und Klimaschutzes und sich im noch ausstehenden wasserrechtlichen Planfeststellungsbeschluß für den Erhalt der Teiche auszusprechen.
Trotz der Tatsache, dass die EU-Kommission dem Antrag zur Beseitigung der Lacomaer Teiche eine lückenhafte Argumentation bescheinigt, hat sie mit Schreiben vom 24. November einer Abbaggerung der Teiche zugestimmt - ROBIN WOOD liegt die Stellungnahme vor. Lückenhaft sei die Argumentation im Antrag insbesondere in Bezug auf eine preisgünstige und sichere Energieversorgung, die nur durch die unter den Lacomaer Teichen lagernde Braunkohle zu erreichen sei. Auch sei ganz allgemein versäumt worden, eine Umstellung der Energieversorgung unter anderem auf Gas zu prüfen.

Die EU-Kommission hat sich fatalerweise dennoch der Bewertung des Konzern Vattenfall angeschlossen, wonach alle Alternativen zur Inanspruchnahme der Teiche, z.B. eine Leistungserhöhung im Tagebau Jänschwalde oder im Tagebau Welzow-Süd, eine vorzeitige Weiterführung des Tagesbaus Reichwalde in Sachsen oder der Ausbau Erneuerbarer Energien zusätzliche - nicht zumutbare -Investitionen des Konzerns erforderten.
Diese Bewertung erfolgte vor dem Hintergrund, dass der schwedische Konzern Vattenfall seine Gewinne aus der Braunkohleverstromung in Deutschland von Jahr zu Jahr steigern konnte. Zuletzt hatte der Konzern Ende Oktober einen Vorsteuergewinn im dritten Quartal von 13,2 Prozent auf 330 Millionen Euro bekannt gegeben. Die Gewinne konnten nach Konzernangaben gegenüber dem Vorjahr aufgrund der geringen Brennstoffkosten und der hohen deutschen Strompreise gesteigert werden.

"Damit die stetig steigenden Gewinne des Konzern Vattenfall auch künftig weiter steigen, darf ein nach europäischem Recht besonders schützenswertes Gebiet zugunsten der klimaschädlichen Braunkohleverstromung vernichtet werden. Diesen Sachverhalt mit einem übergeordneten öffentlichen Interesse zu begründen, wie es die EU-Kommission getan hat, ist mehr als dreist/", so Bettina Dannheim, Energiereferentin von ROBIN WOOD. "Die Aussagen der Kommission, sich für einen engagierten Klima- und Naturschutz einzusetzen, haben sich mit der Genehmigung zur Abbaggerung der Lacomaer Teiche als doppelzüngig erwiesen."

ROBIN WOOD wird sich auch weiterhin für den Erhalt der Lacomaer Teiche einsetzen. Alle StromkundInnen von Vattenfall fordert ROBIN WOOD auf, dem Konzern die rote Karte zu zeigen und zu einem Ökostromanbieter zu wechseln.

Für Rückfragen: Bettina Dannheim, Energiereferentin ROBIN WOOD,

Tel.: 040 / 380 892 22,
E-mail: energie@robinwood.de
Weitere Informationen unter: www.robinwood.de/lacoma

Ute Bertrand / Pressesprecherin / ROBIN WOOD Nernstweg 32, 22765 Hamburg
Tel. ++49 (0) 40 / 380 892-22, presse@robinwood.de, www.robinwood.de

Green Power Inc. Demonstrates Waste-To-Fuel Technology Creating 'NanoDiesel'

2006-09-15T12:45:00.000+02:00

SOURCE: Green Power

Green Power, Inc. demonstrated their new technology of turning everyday landfill waste into diesel fuel, in a process called Catalytic Depolymerization. ('low-temperature process')

Quite unclear what is meant by 'NanoDiesel'

'A typical 500 ton-per-day plant is actually 5, 100-ton plants stacked together. This provides an element of redundancy, standardization and reliability. The entire plant does not have to be shut down for maintenance or repair. Additionally, manufacturing costs will be reduced. As a site s capacity needs to increase, additional units can be added without a major redesign.'

'The cost to produce the fuel will be extremely competitive, estimated at .52 to .58 USD per gallon.'

Energy Gains And Environmental Impacts Of Corn Ethanol And Soybean Biodiesel

2006-09-08T09:00:00.000+02:00

Study to be published in the July 11 Proceedings of the National Academy of Sciences - Abstract

SOURCE: University of Minnesota

"Quantifying the
benefits and costs of biofuels throughout their life cycles allows us
not only to make sound choices today but also to identify better
biofuels for the future," said Jason Hill, a postdoctoral researcher in
the department of ecology, evolution, and behavior and the department
of applied economics and lead author of the study.

Soybean biodiesel
returns 93 percent more energy than is used to produce it, while corn
grain ethanol currently provides only 25 percent more energy.

Soybean biodiesel
produces 41 percent less greenhouse gas emissions than diesel fuel
whereas corn grain ethanol produces 12 percent less greenhouse gas
emissions than gasoline. Soybeans have another environmental advantage
over corn because they require much less nitrogen fertilizer and
pesticides, which get into groundwater, streams, rivers and oceans.

Umwelt-Chemikalien stören Hormonsysteme von Mensch und Tier - EU Studie

2006-08-31T09:14:00.000+02:00

Umwelt-Chemikalien stören Hormonsysteme von Mensch und Tier

"Nach drei Jahren europaweiter Forschung über die gesundheitlichen
Auswirkungen hormonell wirksamer Umweltchemikalien und pflanzlicher
Hormon-Ersatzstoffe hat der Forschungsverbund CREDO (Cluster of
Research on Endocrine Disruption in Europe) seine Ergebnisse vorgelegt.
64 Teams hatten drei Jahre lang den Einfluss von Umweltchemikalien auf
die Hormonsysteme von Tieren untersucht und dabei zum Teil erhebliche
Effekte und Wirkzusammenhänge beschrieben."
......

"Seit Jahren warnen Mediziner und Biologen vor gesundheitlichen Gefahren
durch hormonell aktive Umweltchemikalien synthetischer oder natürlicher
Art. Sie werden als Weichmacher in Nahrungsmittel-Verpackungen
verwendet, kommen als UV-Filter in Sonnencremes vor oder als
Konservierungsstoffe in Hautcremes. Andere Chemikalien werden in großen
Mengen als Insekten- und Unkrautvernichter in der Landwirtschaft
eingesetzt. Die Substanzen bringen das Hormonsystem von Mensch und Tier
durcheinander,........

Einige der im Rahmen des Forschungs-Clusters EURISKED begonnen Untersuchungen werden im Rahmen des EU-weiten "Network of Excellence" mit dem Namen CASCADE (Chemicals as contaminants in the food chain: an NoE for research, risk assessment and education) fortgeführt. Das Forschungsnetzwerk umfasst 24 Arbeitsgruppen in neun europäischen Ländern und untersucht die gesundheitlichen Auswirkungen von Chemikalien-Rückständen in der Nahrung. .....

Applied Colloids Surfactants

Insektenvernichtungsmittel künftig ein zunehmendes Problem für Gewässer in Europa - Helmholtz-Zentrum für Umweltforschung UFZ - Forschen für die Umwelt

Diethylhexyl phthalate (DEHP), bisphenol A, and pesticides Pollute European Water Bodies More Than Previously Thought

Studie: Pestizide belasten Gewässer stärker als gedacht

less than five cents per person per day to provide clean drinking water

Wir.Dienen.Deutschland?

Wir.Dienen.Deutschland.

Triclosan replacement

sensidin® DO – a triclosan alternative for deodorants

Industry urged to take precautions with triclosan

Following various studies on the use of the antibacterial agent triclosan in consumer products, including oral care, experts are urging companies to remove it from their formulations as a precaution.

What is triclosan?

What is known about the safety of triclosan?

Does triclosan provide a benefit in consumer products?

What consumers should know:

How can I tell if there is triclosan in a product that I am using?

What is FDA doing to evaluate the safety of triclosan?

new interest in surfactant enhanced soil clean-up

Asphaltene stability - nonscanning NIR technique: World Congress on Emulsion 2010

A comparative study of asphaltene precipitation/flocculation by a new non-scanning NIR-technique in accordance with ASTM D 7061

test for long term stability - bottom focused back scattering World Congress on Emulsion 2010

Inlined creaming, speeding-up stability evaluation - World Congress on Emulsion 2010

Rapid emulsifier selection, emulsion stability, reformulation - World Congress on Emulsion 2010

Surfactant adsorption kinetics - emulsion stability, World Congress on Emulsion 2010

Characterization of the dispersion properties of carbon nanotubes in ionic liquids by the separation behaviour in the centrifugal field

Bisphenol A Massenchemikalie mit unerwünschten ... UBA Hintergrundpapier

"Blühende Landschaften" am Hindukusch?

III.

SEDIMENTATION AND CONSOLIDATION BEHAVIOUR OF KAOLIN SUSPENSIONS IN PRESENCE OF DISPERSANT

LABORATORY SCALE EVALUATION OF INCLINED SETTLING

FLOCCULATED DISPERSIONS CHARACTERIZED BY DIFFERENT METHODS MEASURING TRANSMISSION

Qualitätskontrolle und Stabilitätsuntersuchungen an Wasserlacken

ACHEMA2009 - Paint products: Accelerated stability and quality testing by direct measurement of separation and segregation

ACHEMA2009 - Photometric instrumentation for evaluation of dispersion stability and optimization

ACHEMA2009 - Speeding up the evaluation of the physical stability of beverage dispersions

ACHEMA2009 - Additive selection and evaluation of dispersion stability for reformulation in the REACH process

Campact Studie Verbot Genmais

Colloids, Grains and Dense Suspensions: under Flow and under Arrest

Particulate Systems Analysis 2008 Depletion flocculation characterised by multisample analytical centrifugation

"öffentliches" Gelöbnis vor dem Reichstag

Easing formulation of suspensions by bottom focused back scattering - Poster at SIS2008

Easing formulation of emulsions by bottom focused back scattering - poster at SIS2008

Sedimentation and consolidation behaviour of mineral suspensions flocculated by adsorbing and nonadsorbing polymers - poster at SIS2008

A New Method Based on Light Backscattering Signals to trace Sedimentation and Creaming - paper at SIS 2008

Rapid emulsifier selection and evaluation of emulsion stability for reformulation - presentation at SIS2008

Farben & Lacke: Schnelle Bewertung von Entmischung und Segregation

Scope

Campact Klimaappell an Merkel und Gabriel

Unterzeichnen Sie den Appell an Merkel und Gabriel

Zukunft statt Kohle!

Separation behaviour of suspensions in polymer solutions WFC 10 World Filtration Conference 10

Evaluation of beverage cloud emulsion stability - Food Colloids 2008

70 % gegen Bahnprivatisierung

Charakterisierung interpartikulärer Kräfte

Chemie Ingenieur Technik Volume 80, Issue 3 , Pages 393 - 397

Änderung des Gentechnik-Gesetzes beschlossen campact aktion

Paint products: Accelerated stability and quality testing

Scope

Formula V - Formulation Science and Technology 2007

making palm oil production less polluting - the wastewater issue

Concerns Over Bisphenol A

Risk due to endocrine effect of compounds used in personal care products

Gefährdungen durch Chemikalien in Bekleidungstextilien - Übersicht

depleted uranium amunition leads to groundwater contamination - Uranmunition im Boden führt zu radioaktiver Grundwasserkontamination

Exposure to depleted uranium (DU) particles strongly increases risk of lung cancer

The Alchemist Newsletter: May 8, 2007

Fast evaluation of dispersion properties for particle size analysis / Charakterisierung der Dispersionseigenschaften für die Partikelgrößenanalyse

Scope

Problemstellung

PERFLUORIERTE VERBINDUNGEN - Hintergrundpapier Umweltbundesamt

Pflanzenschutzmittel in der Umwelt - Übersicht

PARTEC 2007 conference papers

Filtech 2007 conference papers

Application of multisample analytical centrifugation for fast evaluation of long term stability and freeze/thaw stability of emulsions

L.U.M. GmbH, Rudower Chaussee 29 (OWZ), 12489 Berlin, Germany

www.lum-gmbh.com, info@lum-gmbh.de

1 Introduction

Application of multisample analytical centrifugation for fast evaluation of long term stability and freeze/thaw stability of emulsions

L.U.M. GmbH, Rudower Chaussee 29 (OWZ), 12489 Berlin, Germany

www.lum-gmbh.com, info@lum-gmbh.de

sensidin^® DO – a triclosan alternative for deodorants

`A comparative study of asphaltene precipitation/flocculation by a new non-scanning NIR-technique in accordance with ASTM D 7061`