Use Of Organoclay Research Articles

Characterization, performance modeling, and design of an active capping remediation project in a heavily polluted urban channel

Collateral Channel is a heavily polluted former navigation slip to the Chicago Sanitary and Ship Canal (Illinois, USA). Characterization of sediment cores taken in the channel show high levels of heavy metals, polycyclic aromatic hydrocarbons (PAHs) and other contaminants in deposited sediment dating back to the 1800's. Of these, PAHs were the contaminants of greatest concern based upon exceedance of sediment contamination criteria (Σ 16 PAHs up to 1500 mg/kg). Benthic animal counts revealed a lack of biodiversity, with relatively low levels of small tubificid oligochaetes (generally < 3000/m 2) in surficial sediments. Comparison of surficial sediment contaminant levels between 1995 and 2005 showed few decreases in contaminant levels, indicating a lack of “natural recovery” processes occurring in the channel. These results led to an analysis of sediment amendments for an active capping demonstration project in the channel using transport models developed in our previous work (Viana et al., 2008). Based on the sediment characterization and modeling results, the active capping design will be focused on organic contaminant sequestration through the use of organoclay. A site-specific difficulty is the substantial rates of gas ebullition from anaerobic organic matter biodegradation in the sediments, particularly in the summer months. These gases can open advective channels that may result in substantial pollution release and compromise cap effectiveness, and thus the capping scenario must control for such releases. The active capping layer will underlay a sloped sand layer and a high permeability gas venting system to allow biogenically-produced gas migration to shoreline collectors through an innovative support grid. The cap will include an overlaying wetland to remove nutrients from the adjoining Chicago River and provide a public recreational space.

Effect of Humic Acid on Adsorption of Polychlorinated Biphenyls onto Organoclay

Mitigation of risks stemming from contaminated sediments in freshwater and estuarine environments remains an important challenge to the field of environmental science and engineering. Capping sediments with reactive materials is one approach that has recently been the subject of research and development. This research evaluated the use of organoclay as a sorbent in a reactive cap for in situ remediation of contaminated sediments, and provides an original contribution by presenting the sorption characteristics of individual polychlorinated biphenyls (PCB) congeners in the presence of high concentrations of humic acids typical of sediment porewater environments. Sorption of coplanar and noncoplanar PCBs on three commercially available organoclays was studied in this work. Studies were conducted to evaluate the kinetics of adsorption of PCBs on organoclay and to determine the effect of humic acid on the kinetics of adsorption. Isotherm studies were conducted to determine the adsorption affinity of PCBs for organoclays in the presence and absence of humic acid. Studies showed a 45 to 96% reduction in the sorption affinity for organoclays after preloading with high concentrations of humic acid, depending both on the congener and the composition of organoclay. Desorption of PCBs upon addition of humic acid after PCBs were equilibrated with organoclay was statistically significant, although the magnitude of the effect was much smaller than that observed from preloading of humic acid.

Determination of diffusive transport in HDPy-montmorillonite by H2O-D2O exchange using in situ ATR-FTIR spectroscopy

AbstractThe anion adsorption capability of clays can be improved significantly by modification with certain organic cations. However, surface properties and the microstructure of the clay might change and limit the use of organo-clays in barrier systems. In this study an experimental setup is introduced which allows the rapid determination of effective diffusion coefficients (Deff) for H2O in clay samples. H2O→D2O exchange experiments on hexadecyl-pyridinium (HDPy)-montmorillonite samples were performed in a diffusion cell attached to the ATR unit of a Fourier-transform infrared spectrometer. The mean Deff for H2O in a D2O-saturated original montmorillonite is 2.44 × 10–11 m2/s in the bulk density range of 1.1–1.8 g/cm3. Hydrophobic surfaces increase the diffusivity only at high bulk densities in the saturated state. The mean Deff is lower when HDPy is applied in amounts ⩾80% of the cation exchange capacity in comparison with the original sample. At a saturation degree of the pores of 40%, Deff for all samples is one order of magnitude less than in the saturated state. Results on Deff obtained by ATR-FTIR spectroscopy are in good agreement with through-diffusion studies.

P-Nitrophenol, phenol and aniline sorption by organo-clays

The aims of this study were to make use of organo-clays (i.e., Cloisite-10A, Cloisite-15A, Cloisite-30B and Cloisite-93A), to remove p-nitrophenol, phenol and aniline of organic pollutants. The organo-clays were characterized by X-ray diffraction (XRD). Sorption isotherm, kinetic and pH effect of p-nitrophenol, phenol and aniline sorbed by four organo-clays were evaluated. The d-spacings (0 0 1) of the XRD peak of Cloisite-10A, Cloisite-15A, Cloisite-30B and Cloisite-93A are 1.98, 2.76, 1.93 and 2.64 nm, respectively. The d(0 0 1)-spacings of XRD indicated that these p-nitropheno, phenol and aniline could penetrate into the interlayer of clays and expand the d(0 0 1)-spacings. The linear sorption isotherm of constant partition was employed to describe the sorption isotherms of phenols sorbed by organo-clays through hydrophobic–hydrophobic chemical reactions. The parabolic diffusion and power-function of kinetic models were employed to describe properly the kinetic experiments. The rate limiting step of the p-nitrophenol sorption reactions on organo-clays were diffusion-controlled processes (i.e., 15A, 30B, 93A) and chemical-controlled process for 10A organo-clays. The pre-exponential factor of the p-nitrophenol sorbed by four organo-clays showed the trend as follows: 10A > 30B > 93A > 15A. The efficiency of these organo-clays in removing phenol compounds in water treatments merit further study.

Adsorption of hydrocarbons on organo-clays—Implications for oil spill remediation

Organo-clays synthesised by the ion exchange of sodium in Wyoming Na-montmorillonite (SWy-2-MMT) with three surfactants: (a) octadecyltrimethylammonium bromide (ODTMA), formula C 21H 46NBr; (b) dodecyldimethylammonium bromide (DDDMA), formula C 22H 48BrN; and (c) di(hydrogenated tallow)dimethylammonium chloride were tested for hydrocarbon adsorption. Using diesel, hydraulic oil, and engine oil an evaluation was made of the effectiveness of the sorbent materials for a range of hydrocarbon products that are likely to be involved in land-based oil spills. It was found that the hydrocarbon sorption capacity of the organo-clays depended upon the materials and surfactants used in the organo-clay synthesis. Greater adsorption was obtained if the surfactant contained two or more hydrocarbon long chains. Extensive utilisation of chemometrics principally with the aid of MCDM methods, produced models which consistently ranked the organo-clays well above any of the competitors including commercial benchmark materials. Thus, the use of organo-clays for cleaning up oil spills is feasible due to its many desirable properties such as high hydrocarbon sorption and retention capacities, hydrophobicity. The negative effects of the use of organo-clays for oil-spill cleanup are the cost, the biodegradability, and recyclability of the organo-clays.

Micro- and nano-scale deformation behavior of nylon 66-based binary and ternary nanocomposites

The primary aim of this paper is to provide an insight on the effect of the location of organoclay on the micro- and nano-scale deformation processes in melt-compounded nylon 66/organoclay/SEBS-g-MA ternary nanocomposites prepared by different blending sequences. In addition, the deformation processes of the ternary nanocomposites were compared to the binary nanocomposites (nylon 66/organoclay and nylon 66/SEBS-g-MA) and neat nylon 66. The incorporation of SEBS-g-MA particles toughened nylon 66 markedly; but the flexural modulus and strength were both reduced. Conversely, the use of organoclay increased the modulus but decreased the fracture toughness of nylon 66. Nylon 66/SEBS-g-MA/organoclay ternary nanocomposites exhibited balanced elastic stiffness and toughness. Stress-whitening studies of the fracture surfaces in terms of gray level were also performed and an attempt was made to correlate the optical reflectivity characteristics with fracture toughness. It was concluded that the capability of SEBS-g-MA particles to cavitate was decreased by the presence of organoclay in the SEBS-g-MA phase, resulting in reduced toughening efficiency. The best micro-structure for toughness and other mechanical properties is thus to maximize the amount of exfoliated organoclay in the nylon 66 matrix rather than to have it embedded in the finely dispersed SEBS-g-MA particles.

Sorption and detoxification of toxic compounds by a bifunctional organoclay.

Organoclays are excellent sorbents for nonionic contaminants and therefore may have many environmental applications. A major limitation on the use of organoclays is that the contaminant merely changes its location from one environmental compartment to another while still remaining intact. In this study, a new type of organoclay, termed a bifunctional organoclay, has been prepared. It is able not only to sorb organophosphate pesticides, but also to catalyze their hydrolysis, and thereby detoxify them. The bifunctional organoclay prepared in this study is based on sodium montmorillonite, in which the inorganic counter ions are replaced by N-decyl-N,N-dimethyl-N-(2-aminoethyl) ammonium (DDMAEA). The detoxifying capacity of this organoclay for two organophosphate pesticides, methyl parathion [O,O-dimethyl O-(p-nitrophenyl) thionophosphate] and tetrachlorvinphos [2-chloro-1-(2,4,5-trichlorophenyl)ethenyl dimethyl phosphate], was demonstrated. It was shown that although the sorption of these pesticides on the bifunctional organoclay is very similar to that on N-decyl-N,N,N-trimethyl ammonium (DTMA) organoclay (the corresponding nonbifunctional organoclay), the hydrolysis of these pesticides is substantially enhanced only by the bifunctional organoclay. The half-life for the hydrolysis of the investigated pesticides in the presence of the bifunctional organoclay is about 12 times less than for their spontaneous hydrolysis, and the enhancement is even more pronounced relative to the hydrolysis of these pesticides in the presence of the DTMA organoclay (which actually inhibits their hydrolysis). Based on kinetic measurements, the pK(a) of the ethylamino group of the bifunctional organoclay was estimated to be around 9.0. It is postulated that the catalytic effect of the bifunctional organoclay can be attributed to a nucleophilic attack of the unprotonated ethylamino group of the organoclay on the organophosphate ester.

The use of organo-clays in water treatment

The use of organo-clays in wastewater treatment has become commonplace in industry today. Organo-clays exhibit a synergistic effect with many commonly utilized water treatment unit processes including granular-activated charcoal, reverse osmosis, and air strippers. Organo-clays have proven to be the technology of choice for treating oily wastewaters. This paper will discuss the physical chemistry of the organo-clays sorption mechanism as well as numerous examples of where the technology has been applied.

Süd-Chemie acquires Alcan’s organoclay technology for fire retardants

Süd-Chemie AG, headquartered in Munich, Germany, has acquired the intellectual property and know-how relating to the use of organoclays with inorganic fire retardants from Alcan Aluminium UK Ltd. The sale by Alcan comes as a result of the closure of its UK chemicals operations in Burntisland late last year. Alcan and Süd-Chemie were previously involved in a cooperative development programme to exploit the benefits of this technology for polymer materials. This is a short news story only. Visit www.addcomp.com for the latest additives and compounding industry news.

UOP joins Süd-Chemie in new fuel cell company

Süd-Chemie AG, headquartered in Munich, Germany, has acquired the intellectual property and know-how relating to the use of organoclays with inorganic fire retardants from Alcan Aluminium UK Ltd. The sale by Alcan comes as a result of the closure of its UK chemicals operations in Burntisland late last year. Alcan and Süd-Chemie were previously involved in a cooperative development programme to exploit the benefits of this technology for polymer materials.This is a short news story only. Visit www.addcomp.com for the latest additives and compounding industry news.

Organo-Clay Complexes and Interactions, edited by S. Yariv and H. Cross. Marcel Dekker New York, (2002), viii + 688 pages. [ISBN 0 8247 0586 6]. Price $195.

This book contains 11 chapters, four of which are written or co-written by Shmuel Yariv. Despite the number of pages, it does not offer a comprehensive review and the editors acknowledge this in the preface before expressing the intention to remedy this in a second volume. From my own perspective the major omissions are in the areas of kaolin-organic interactions and the use of organoclays as adsorbents and barrier materials. However, given the enormous number of publications that have emerged in recent years in both these areas, it is perhaps understandable. Moreover, given the amount of (sometimes repetitious) attention to alkylammonium-exchanged clays in this volume it is surprising that little mention is made of their importance in clay-based nanocomposites. The book opens with a chapter devoted to the ‘Structure and Surface Acidity of Clay Minerals’ by S. Yariv and K.H. Michaelian (35 pages, 44 references). Twenty pages are devoted to the structure of 1:1 and 2:1 layer silicates and are used as a prelude to a well-structured discussion of the water present in the gallery and how it is influenced by the type of exchangeable cation and the locus of isomorphous substitution. There is also a discussion of the surface acidity/basicity of clays and how it is affected by the occupancy of the octahedral sheet. The second chapter ‘Introduction to Organo-Clay Complexes and Interactions’ by S. Yariv (72 pages, 188 references) positions clay-organic interactions with respect to their role in fixation and/or transport of organic matter in the environment, industry and …

Using organoclays to enhance carbon filtration

Organoclays have found increased acceptance as pre-treatment for activated carbon adsorption systems in both groundwater and wastewater cleanup. The reason is that activated carbon tends to become quickly blinded by large organic molecules of low solubility, particularly oils. However, it is also well established that activated carbon is more efficient at low concentrations of organic contaminants than at higher ones, i.e. at less than 1 ppm. With organoclays it is exactly the opposite, they are better at removing organics at higher concentrations, above 3 ppm. Therefore it is cost effective in these applications to use two or more vessels in series, the first one filled with organoclay, the remainder with activated carbon. The economics make sense, even though the organoclay is not regenerated, because of the reduction in down time every time a carbon vessel has to be changed out. Use of organoclays increases the volume treated by carbon in many applications seven to nine fold. In the case of other organic contaminants, as the aqueous solubility increases, the efficiency decreases, except in the case of methylene chloride, which it removes at far higher efficiency then carbon. This article presents the results of a series of tests, including K d determinations, jar tests, and mini-column tests. These tests determined the adsorption capacity and efficiency of organoclay and activated carbon for the removal of benzene, toluene, xylene and naphtalene from water. These tests were followed by adding the four compounds into one container to see if the combination of organoclay, followed by carbon, would be more efficient then each sorbent alone. The tests also compared the efficiency of organoclay versus carbon for the removal of various oils from water.

Organoclay with Soil-Bentonite Admixture as Waste Containment Barriers

Organoclays, clays modified by cationic surfactants, for engineering applications have recently drawn great attention because of their high organic removal capacity. In this study, the potential use of organoclays with soil-bentonite admixtures as waste containment barriers is investigated by experimental tests such as batch equilibrium sorption studies, compaction tests, and hydraulic conductivity tests. Sorption isotherms of total organic carbon (TOC), a gross organic term, by five different types of soil admixtures are nonlinear. The soil specimen with more organoclays exhibits higher organic sorption capacity and a larger retardation factor. The specimens with 20% by dry weight of bentonite have higher optimum water content and plasticity. With the addition of bentonite in the soil material consisting of completely decomposed volcanic rock (CDV) (natural soils) and organoclays, the hydraulic conductivity to leachate decreases from about 10−7 to 10−8 cm/s. This indicates that the presence of bentonite ...

Use of Organoclay as Secondary Containment for Gasoline Storage Tanks

Conventional clay liners, which are widely used as hydraulic barriers to water, have been shown to be adversely affected by organic fluids. However, the addition of quaternary amines into bentonite greatly enhances its compatibility with organic fluids and thus allows the clay barrier technology to be extended to the treatment of organic contaminants. In this study, an organically modified clay was studied for use as a secondary containment for gasoline underground storage tanks. Free swelling and hydraulic conductivity tests were performed on organoclay, pure bentonite, and natural soils. Results show that organoclay has a large swelling capacity in gasoline, whereas bentonite and natural soils shrink when immersed in gasoline. The hydraulic conductivities of bentonite and natural soils to gasoline are 2–5 orders of magnitude higher than that to water. In contrast, the hydraulic conductivity decreases by 2 orders of magnitude for organoclay and this low value can be maintained even under freeze-thaw and ...

USING ORGANOCLAYS TO ENHANCE CARBON FILTRATION

Organoclays have found increased acceptance as pre-treatment for activated carbon adsorption systems in both groundwater and wastewater cleanup. The reason is that activated carbon tends to become quickly blinded by large organic molecules of low solubility, particularly oils. However, it is also well established that activated carbon is more efficient at low concentrations of organic contaminants than at higher ones, i.e. at less than 1 ppm. With organoclays it is exactly the opposite, they are better at removing organics at higher concentrations, above 3 ppm. Therefore it is cost effective in these applications to use two or more vessels in series, the first one filled with organoclay, the remainder with activated carbon. The economics make sense, even though the organoclay is not regenerated, because of the reduction in down time every time a carbon vessel has to be changed out. Use of organoclays increases the volume treated by carbon in many applications seven to nine fold. In the case of other organic contaminants, as the aqueous solubility increases, the efficiency decreases, except in the case of methylene chloride, which it removes at far higher efficiency then carbon. This article presents the results of a series of tests, including Kd determinations, jar tests, and mini-column tests. These tests determined the adsorption capacity and efficiency of organoclay and activated carbon for the removal of benzene, toluene, xylene and naphtalene from water. These tests were followed by adding the four compounds into one container to see if the combination of organoclay, followed by carbon, would be more efficient then each sorbent alone. The tests also compared the efficiency of organoclay versus carbon for the removal of various oils from water.

Kinetics of Phenol and Aniline Adsorption and Desorption on an Organo-Clay

The use of organo-clays in wastewater treatment, as alternatives to activated C for sorbing pollutants, and in clay liners is of great interest to soil and environmental scientists. There is a lack of information, however, on the kinetics and mechanisms of organo-clay interactions with pollutants. Accordingly, in this study, the time-dependent adsorption and desorption of phenol and aniline on hexadecyltrimethylammonium-montmorillonite (HDTMA-Montmorillonite) from aqueous solutions were determined in a stirred-flow chamber. The experiments were conducted at two concentration levels, 0.001 and 0.01 mol L-1 for aniline, phenol, and their mixed solutions. Carbon-labeled (14C) solutes were used in the study. Adsorption of both phenol and aniline was completed within 40 min and desorption in 20 min. When the sorptives were mixed, the rates of adsorption-desorption were not significantly affected. The rate of phenol adsorption was influenced by sorptive concentration while the rate of aniline adsorption was independent of sorptive concentration. Various mechanisms appear to be involved in the adsorption processes.

The Use of Organoclays to Reduce Organic Waste Volatilization During Solidification

One of the major difficulties experienced when solidifying organic waste is the volatilization of organic compounds during mixing and curing. The occurrence of volatilization has made solidification's ability to reduce organic waste leachability suspect. This paper recounts the ability of organoclays to reduce the volatilization of nitrobenzene (NB) and 1,2-dichlorobenzene (DCB) from cement-based solidification samples. The results indicated the incorporation of organoclays reduced the volatilization caused by cement-based solidification of NB and DCB to 1/6 and 1/10 of their original values, respectively. The samples utilizing the organoclays retained the majority of NB and DCB added to them, 65-100% and 63-94%, respectively. The ability of organoclays to reduce volatilization appeared to be inversely correlated to their increasing percent organic matter content.

The Use of Organo-Clays as Gas Chromatographic Stationary Phases.

The Use of Organo-Clays as Gas Chromatographic Stationary Phases.