Applied Colloids Surfactants

Interessante Zusammenstellung vom Bayrischen Landesamt für Umweltschutz

Umweltchemikalien mit hormoneller Wirkung

zitiert aus der Einleitung
Zahlreiche Forschungsergebnisse deuten weltweit auf eine Zunahme von Fortpflanzungs- und Entwicklungsstörungen hin: Bei Tieren wurde eine Verringerung der Fruchtbarkeit, eine Verweiblichung der Männchen und ein verändertes Sexualverhalten festgestellt. Beim Menschen wird eine Abnahme der Spermienzahl diskutiert und eine Zunahme von Brust- und Hodenkrebs beobachtet. Immer wieder geraten Umweltchemikalien mit hormoneller Wirkung als Ursache in die Diskussion. Wir geben Ihnen in dieser Publikation einen knappen Überblick über dieses Thema, an dem derzeit intensiv geforscht wird.

see also Surfactants for bioremediation of clay

Question by Gary Canny
I was wondering if anyone knows of suppliers of Fenton's reagent in Europe
more specifically in Ireland or someone who is willing to supply the reagent
to Ireland.

I was looking to apply the reagent to a site we have which has been
contaminated with diesel, to an area of contaminated clay material situtated
beneath the foundation of a house which cannot be excavated due to the
structure of the house.

Has anyone used Fenton's reagent in such a situation, is there any problems
I should look out for and are there any known techniques out there for the
deliver of such a reagent into a clay material.

Answer
I just found the following at http://www.clu-in.org/products/tins/

IN-SITU GROUNDWATER REMEDIATION BY FENTON'S REAGENT INJECTION: A CASE STUDY
Smith, M., Wardrop Engineering Inc., Winnipeg, MB, Canada.
Canadian Reclamation, p 4-8, Winter-Spring 2005 [OSTI: DE20607332]

A quarter-hectare site that once hosted a bulk fuel facility was heavily contaminated by a variety of released hydrocarbons. Because the site is underlain by an unconfined aquifer used for drinking water, the cleanup goals aimed to meet Health Canada's stringent guidelines for Canadian drinking water quality. The cleanup was undertaken using in situ chemical oxidation, which involves the injection of chemical oxidants into the subsurface for direct treatment. Fenton's reagent, a combination of hydrogen peroxide and iron sulphate, was used to take advantage of the oxidizing strength of the hydroxyl radicals. Injection of the reagent took place during three separate events in August 2003 and July and September 2004. Ground-water samples from a total of 11 on- and off-site wells were tested for BTEX (benzene, toluene, ethylbenzene, xylenes) and total volatile hydrocarbons immediately prior to each injection. The injections were constantly monitored to prevent excessive gas evolution through the site surface. Maximum total BTEX concentrations in excess of 9.0 mg/L in August 2003 were reduced to below 0.4 mg/L by September 2004. As of September 2004, all off-site wells complied with the standards prescribed by the guidelines for Canadian drinking water quality. Bacterial population increased dramatically over the injection period, suggesting that aerobic respiration has been an important contributor in the degradation of petroleum constituents in the soil and the ground water.

Further, I think the Fentons reagent should be prepared immediately before injection at place.

Answer by John Haselow
there are a number of options available.

Classical Fenton's chemistry involves a transmission metal (typically ferrous
iron) and hydrogen peroxide under acidic conditions.
You should be able to purchase hydrogen peroxide, ferrous sulfate (for
example), and some inorganic acid in Ireland.

There are other options that involve calcium peroxide, chelated iron, etc
that can be used also.

We have used a mixture of sodium persulfate and calcium peroxide also for
residential applications. It is a lot safer to work with.

If you decide to do this yourself with Fenton's chemistry, be extremely
careful, because you are bringing a strong oxidant in contact with fuel and
heat, which can lead to unsafe conditions if you don't know what you are
doing.

Steve Short
Due to its extreme instability/reactivity Fentons Reagent cannot as such be
prepared for sale and supplied.

In fact Fentons Reacgent is simply hydrogen peroxide (of various grades) to
which a ferrous chloride or sulfate solution is dosed just prior to
injection. The ferrous ion catalyses the (free radical) oxidation.

You will need to separately source the peroxide and the FeCl2 solution and
set up some sort of dosing/mixing arrangement.

Hendrik van Herzeele
See www.insitu.nl

Xingzhi Wu
I am doing research on in situ bioremediation of PCE contaminated soil. For
low hydraulic permeable clay, it is very hard to deliver reagent into it. On
the other hand, as the clay was contaminated, there should be some pathway
for diesel transport into the clay, such as fracture. Find the pathway, and
inject the reagent through it. Otherwise, try electroosmosis flow injection.
The reagent is very active and may not stay long time in soil.

Fred Heyrich

Fred Heyrich
As with most inquiries, etc. I probably Need a little more information before I shoot my mouth off.

Q.: pH of Diesel+ and soil. If alkaline, no problem, I can tell you how or send you A VERY modified Fenton Redox effective in Alk. pHs. Is the house occupied? Sounds like the amount of soil to be remediated is relatively small anyway, so I'll shoot my mouth off anyway! Also I have been persuaded that ""finish" remediation should be biological. Also, how the heck did diesel fuel get there? It would help if there had been an analytical concn., C-chain, etc. Using a consortium of bacteria would work without the Fenton R. (VERY) modified but would produce odor and would be considerably slower.

Another alternate would be to use an absorbant inoculated with surfactant and consortia of bacteria, (non-paths)and other agents which degrade and emulsify HCs, which would :

1. effectively encapsulate the HC liquids, [mixing required] emulsify the HC into fatty acids and triglycerides of fatty acids and.2. the consortium of bacteria, yeasts and molds, begin degradation further, in about 2 hours; Est. time to be reduced to 100 ppm is about 2 weeks. The absorbant bacteria need about 30 % moisture during that time. The times I have remediated diesel containing oxyginating additive as well as usual BTEX under pumping stations, near foundation levels, the whole project took about 2 weeks to satisfy levels which were analyzed to be ND. I would most probably recommend the latter remediation since you appear to be not very familiar with Fenton reactions. If interested I would need to know the cubic yards of contaminated soil and the approximate concentration. Incidentally this also worked in a house crawl-space where the drain had collapsed and considerable grease and feces had spilled. The absorbant + 30% moisture was mixed together by the plumber. The odor was abated in about 3 days [and they moved back in] and it took about 2 weeks to finish. The absorbent and degraded stuff were left in place and an additional layer of absorbent was placed at the request of the homeowner "just in case the new drain had a problem". Make a date to recheck, in about 30 days, I did and we had a damn crop of mushrooms. [if that happens I'll tell you how to kill them out. [Some of our composters sell the degraded stuff for potting soil].

James Cashwell
We've just completed a similar project where Fenton's Reagent was used
to treat saturated soils impacted with residual coal tar (PAHs and BTEX)
at concentrations as high as 30,000 mg/kg. The impacts were found under
an old house, and we installed directional injectors.
Fenton's should work well in your situation, but I suggest that you
consider the installation of vent wells around the perimeter of the
house. If you have significant concentrations of diesel present, the
oxidation process will result in a significant amount of gas (CO2 and
oxygen). The site will need to breath if the soils are too tight or the
house foundation is too large to allow for sufficient off-gassing.
Otherwise, your injection rate will likely decrease and your treatment
effectiveness may be limited.

see also Open source - Surfactants combinations for enhanced bioremediation

Question by Bob Brooks

Is anyone familiar with the use of surfactants to aid in bioremediation of clay.

I have been investigating the possibility of using a surfactant for soil washing. Many of the companies that sell these products make some fairly exaggerated claims. One chemist from a surfactant company suggested using Liquid Humus to prep the clay followed with surfactant and microbes.

Digging up the contamination on site is preferred but not practical due to numerous utilities present.

If anyone has any experience or knowledge of surfactants, I would appreciate the advice.

Answer
what is your purpose - bioremediation or soil washing or one of several combinations of the two?
Further, the chemical composition of the contaminant and distribution/binding of the contaminant is of great importance!
For soil washing (unless the contamination is not present as separate phase or highly volatile) the high surface area of clay will result in need of high surfactant concentrations to achieve efficient removal. Even in case of a tailor-made surfactant combination you will need at least a 1 - 2 % aqueous solution.
Soil washing as a pretreatment step might ease subsequent bioremediation.
Addition of surfactants in low concentration might work in some cases to enhance bioremediation provided there are capable biodegraders in place.


Answer by Fred. J. Heyrich

I have been encountering clay, cleche, aggregae and the mix, sometimes just sand which is a distinct pleasure to work in. On the compacted sils, following a lead from the Aussies, I use a modified Fenton Reagent, following a fairly dilute application of a wetting, surfactant/penetrating agent with some sodium silicate to reduce foaming and try to be patient for about 2 days. Per monitor hole [now also a treatment hole] softens and partially slurries the clay/cleche

to an area about 4 -6 feet, depending on just how compact the "soil" is. I have also, when I didn't have reagents handy used vinegar and bicarbonate mix. KIn each case, pull up samples and use them on the spot [lab-scale] to determine strengths. Then I added our consortium of bacteria, molds and yeasts and fungi (I know the difference). We sample about 3 feet away from the previous monitor hole, to what ever depth the hole was originally. Modified Fenton also serves to gradually release Oxygen for the consortium.

My proportions are millimole.

42nd Meeting of the German Colloid Society - Kolloidgesellschaft
Smart materials: foams, gels and microcapsules
September 26 - 28, 2005, Aachen, Germany

Paper
Characterization of porous bead celluloses by analytical centrifugation

T. Sobisch and D. Lerche

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

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

S. Fischer, C. Fanter

Fraunhofer IAP Geiselbergstr. 69 14476 Potsdam-Golm

Porous bead celluloses have wide ranging potential applications as separation media and carrier systems in the field of pharmacy and foods. Physicochemical characterization of these materials and related suspensions is essential for quality control and technical applications. This includes their surface properties, porosities and mechanical properties.

The paper describes the application of multisample analytical centrifugation for porous bead celluloses allowing a qualitative and quantitative characterization.

The method traces 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.

Bead cellulose is regenerated spherical porous cellulose, manufactured by a special dispersing method starting from different cellulose derivatives. Such samples of different sizes and differing in the preparation process were chosen and analysed in respect to porosity, surface, morphology and particle size distribution.

The consolidation, packing behaviour and elasticity of the bead celluloses was analysed in an alternating centrifugal field.

Differences in packing density obtained under controlled conditions were related to the porosities of the samples. Different preparation processes lead to an alteration of the surface properties of the bead celluloses.

Further bead celluloses revealed a markedly different behaviour than cellulose powder manufactured from native cellulose.

42nd Meeting of the German Colloid Society - Kolloidgesellschaft
Smart materials: foams, gels and microcapsules
September 26 - 28, 2005, Aachen, Germany

Poster

Characterization of thermosensitive PNIPAM microgels by analytical centrifugation

T. Sobisch and D. Lerche

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

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

I. Berndt

Institute of Physical Chemistry, University of Kiel

Olshausenstr. 40 – 60, 24098 Kiel

W. Richtering

Institute of Physical Chemistry, RWTH Aachen University, Landoltweg 2, 52074 Aachen

Aqueous microgel suspensions are characterized by a strong dependence of particle size on temperature tuneable by the degree of cross linking.

Microgel particles are often applied as a physical model for soft deformable particles, for the study of rheological properties and phase transitions.

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 microgel particles as function of concentration, temperature and centrifugal pressure applied.

The method allows to trace 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.

The microgel particles were synthesized by emulsion polymerization of N-isopropylacrylamide in presence of the cross linker N,N´-Methylen-bis-acrylamide. The microgel particles were characterized by dynamic light scattering and capillary viscosimetry.

During centrifugation microgel dispersions split into a nearly particle free top layer, a normal microgel suspension middle layer and an ordered bottom layer showing Bragg diffraction. The layering remains stable even after prolonged standing after centrifugation.

The volume of the bottom layer changes with the overall microgel concentration, temperature and centrifugal pressure.

Particulate Systems Analysis 2005 21 - 23rd September PSA 2005

Stratford upon Avon, UK

Consolidation of concentrated dispersions of nano- and microparticles determined by analytical centrifugation

D. Lerche, T. Sobisch

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

ABSTRACT:

The consolidation behaviour of suspensions was experimentally analysed by means of a multisample analytical photocentrifuge. Experiments were conducted covering a broad range of volume concentrations and centrifugal accelerations. The obtained material functions allow to simulate batch sedimentation, filtration and consolidation. For only hydrodynamically interacting particles the separation velocity decreases with the volume concentration. The so-called hindered settling rate may be fitted to a power law. Interacting particle systems above the gelpoint have to be described by the compressive yield stress. The compressive properties of stable and flocculated dispersions can be easily determined by multisample analytical centrifugation for rapid classification and tailoring of dispersion properties.

Keywords: analytical centrifugation, consolidation, particle interaction, flocculation

1 Introduction

Separation of a dispersed phase from a fluid is extremely important from both theoretical and industrial viewpoints. Sedimentation and consolidation phenomena are crucial in decanter operation as well as in cake filtration and membrane filtration. It was comprehensively elaborated that these processes may be described by a unified theory of solid-liquid separation of non-interacting as well as flocculated suspensions (Landmann 1994; Garrido 2000). However, this mathematical description requires the knowledge of the characteristic material parameter of the dispersions as function of the volume concentration. Until now the prediction of these parameter is not possible. Their broad variation range for different dispersions requires efficient analytical tools.

In this paper the experimental setup of a multisample analytical centrifuge for determination of the characteristic material properties related to the sedimentation and consolidation behaviour of dispersions is described. Accompanied by a brief description of the theory the potential of analytical centrifugation is demonstrated for dispersions of non-interacting rigid and deformable particles and for flocculated systems as well.

Particulate Systems Analysis 2005 21 - 23rd September PSA 2005

Stratford upon Avon, UK

Particle Size Distribution by Space or Time Dependent Extinction Profiles obtained by Analytical Centrifugation

T. Detloff, T. Sobisch and D. Lerche

L. U.M. Gesellschaft für Labor-, Umweltdiagnostik & Medizintechnik mbH
Rudower Chaussee 29 (OWZ) 12489 Berlin / Germany
e-mail info@lum-gmbh.de, www.lum-gmbh.com

ABSTRACT

The particle size distribution of suspensions of fine particles were determined by a photocentrifuge from the transmission / extinction profiles. Photocentrifuges provide a useful tool for the characterization and quality control of suspensions. While the variation of the light extinction curves caused by centrifugal segregation allows a qualitative description, a rigorous formulation can give access to a quantitative characterization. The present work reports on the determination of the particle size distribution using space and time resolved extinction profiles. The particle size distribution is obtained by analysing the variation of the extinction at any point of the sample over centrifugation time or by analysing the extinction variation over the entire sample length at any time span of centrifugation. The advantage of the second method is its potential to save time.

Keywords: particle size analysis, sedimentation, analytical centrifugation, extinction profiles

1 INTRODUCTION

The characterization of the dispersed state of suspensions and emulsions is essential for technical applications in diverse fields such as nanomaterials, coatings, paper making, ceramics, cosmetics, sludge dewatering, to name only a few. Techniques are preferable, which avoid dilution, thus do not modify dispersion properties. In this respect analytical centrifugation has a great potential, however, it was seldom exploited. Today the measurement of the particle size distribution (PSD) of dispersions by sedimentation in a centrifugal field is conducted by analysing the variation of the extinction at one position over the measurement time using line start or homogeneous technique. This method (Constant Position) leads to an integral which only can be solved approximately (all particles have to be homogenously distributed in the dispersion at the beginning). It is also necessary that all particles have passed the detector (ISO 13318, Allen (1999)). One measurement could take a long time, depending on the material properties of the dispersion. An alternative faster solution is provided by analysing the dispersion concentration over the entire sample length at least at one time. This method (Constant Time) has the advantage that an analytical solution with algebraic equations is possible and enables to reduce the time of measurement considerably, because it is not required that all particles are settled out.