clay and illite

Both sediment recycling and first-cycle input influence the composition of clastic material in sedimentary systems. This paper examines conceptually the roles played by these processes in governing the composition of clastic sediment on a regional scale by outlining the expected effects on sediment composition of protracted sediment recycling and of continuous first-cycle input on a maturing continental block. Generally speaking, long-term recycling tends to enrich sediments in the most chemically and mechanically stable components: quartz in the sand and silt size fractions, and illite among the clay minerals. Sandstones trend towards pure quartz arenites, and mudrocks become more potassic and aluminous. The average grain size of clastic sediment decreases by a combination of progressive attrition of sand grains and ongoing breakdown of primary silicate minerals to finer-grained clay minerals and oxides. Sandstones derived by continuous first-cycle input from an evolving continental crustal source also become increasingly rich in quartz, but in addition become more feldspathic as the proportion of granitic material in the upper continental crust increases during crustal stabilization. Associated mudrocks also become richer in potassium and aluminum, but will have higher K2O/Al2O3 ratios than recycled muds. The average grain size of the sediment may increase with time as the proportion of sand-prone granitic source rocks increases at the expense of more mud-prone volcanic sources. In general, except in instances where chemical weathering is extreme, first-cycle sediments lack the compositional maturity of recycled detritus, and are characterized by the presence of a variety of primary silicate minerals. Sedimentary systems are not usually completely dominated by either recycling or first-cycle detritus. Generally, however, sedimentary systems associated with the earliest phases of formation and accretion of continental crust are characterized by first-cycle input from igneous and metamorphic rocks, whereas those associated with more mature cratons tend to be dominated by recycled sedimentary material.

Topics: Aluminum Oxide; Aluminum Silicates; Clay; Colorado; Earth, Planet; Evolution, Planetary; Geologic Sediments; Geological Phenomena; Geology; Minerals; Oxides; Particle Size; Potassium Compounds; Quartz; Weather

Phyllosilicate minerals are the important components in soils and an important source of activated aluminum (Al) during soil acidification. However, the mechanisms for Al activation in phyllosilicate minerals were not understood well. In this paper, the effect of phyllosilicate surface hydroxyl groups on Al activation during acidification was studied after the minerals were modified with inorganic and organic materials. After modification of kaolinite, montmorillonite, and illite with fulvic acid (FA-), iron oxide (Fe-), Fe combined with FA (Fe-FA-), and siloxane (Si-O-), the interlayer spaces were altered. For instance, when modified with Fe, Fe entered the interlayer spaces of kaolinite and montmorillonite and changed the interlayer spaces of both minerals but did not affect that of illite. Also, the other modification methods had significant effects on the interlayer space of montmorillonite but not on kaolinite and illite. It was observed that all the modification strategies inhibited Al activation during acidification by reducing the number of hydroxyl groups on the mineral surfaces and inhibiting protonation reactions between H

Topics: Adsorption; Aluminum; Aluminum Silicates; Bentonite; Clay; Hydrogen-Ion Concentration; Kaolin; Minerals; Soil

Heterogeneous reaction of NO

Topics: Aerosols; Arizona; Bentonite; Clay; Dust; Kaolin; Minerals; Nitrogen Dioxide

Mineral particles in air could provide atmospheric chemical reaction interface for gaseous substances and participate in atmospheric chemical reaction process, and affecting the status and levels of gaseous pollutants in air. However, differences of the heterogenous reaction on the surface minerals particles are not very clear. Considering main mineral composition of ambient particles was from dust emission, therefore, typical clay minerals (chlorite, illite) and desert particles (Taklimakan Desert) were selected to analysize chemical reaction of NO

Topics: Aerosols; Clay; Dust; Environmental Pollutants; Gases; Minerals; Nitrates; Nitrogen Dioxide

In this study, a combination of column experiments, interface chemistry theory and transport model with two-site kinetics was used to systematically investigate the effect of pH on the transport of polystyrene nanoparticles (PSNPs) in porous media. The porous media containing quartz sand (QS) and three kinds of clay minerals (CMs)-kaolinite (KL), illite (IL) and montmorillonite (MT), was used in column experiments to simulate the porous media in the soil-groundwater systems. Experimental results showed that the inhibitory effect of CMs on the transport of PSNPs is weakened as pH increases. The two-dimensional (2D) surface of the DLVO interaction energy (2D-pH-DLVO) was built to calculate the interactions between PSNPs and CMs under different conditions of pH. Results suggested the inflection point of PSNP-QS, PSNP-KL, PSNP-IL and PSNP-MT are 2.42, 3.30, 2.84 and 3.69, respectively. Most importantly, there was a significant correlation between the two-site kinetic parameters related to PSNPs transport and the DLVO energy barrier (DB). The contributions of the interactions of PSNPs-PSNPs and PSNPs-minerals were determined for PSNPs transport in porous media. The critical values of pH related to the migration ability of PSNPs in porous media could be determined by a combination of column experiments, 2D-pH-DLVO and PSNPs transport model. The critical values of pH were 2.95-3.01, 3.22-3.51, 2.98-3.02, 3.31-3.33 for the migration ability of PSNPs in QS, QS + KL, QS + IL and QS + MT porous media, respectively. The stronger migration ability of PSNPs under high pH conditions is attributed to the enhanced deprotonation of the media surface and increased negative surface charge, which increases the electrostatic repulsion between PSNPs and porous media (QS, CMs). Moreover, the agglomeration of PSNPs usually is weaker and the average particle size of agglomerates is smaller under the condition of high pH, thus leading to the stronger migration ability of PSNPs under high pH conditions.

Topics: Clay; Kaolin; Kinetics; Microplastics; Minerals; Polystyrenes; Porosity; Quartz; Sand

The sorption of antibiotics on soil minerals and their cotransport have been widely studied for the past few years; however, these processes in concentrated salt solutions (estuary-like conditions) are not fully understood. This study aims to determine the possible sorption of oxytetracycline (OTC) on various natural and synthesized microsized minerals (including haematite, goethite, kaolinite, bentonite, lateritic, kaolinitic and illitic soil clays) under conditions mimicking pure, fresh, brackish and sea waters. The sorption of OTC was found to decrease in surface charge (herein zeta potential), hence altering the colloidal properties of the materials used. The sorption capacities of soil clays for OTC follow the inequality illitic soil clay > kaolinitic soil clay > lateritic soil clay, and the sorption capacities were found to decrease at higher salt concentrations. Seawater can intensify the release of the sorbed OTC from soil clay surfaces while favouring the coaggregation of the remaining OTC with soil clays. This implies that the long-range transport of OTC or other similar antibiotics can be governed by the mineralogical composition/properties of the suspended particles. More importantly, increasing salt concentrations in estuaries may form a chemical barrier at which limited amounts of OTC/antibiotics can pass through, while the remaining OTC/antibiotics can be favoured to aggregate simultaneously with suspended mineral particles.

Topics: Adsorption; Aluminum Silicates; Anti-Bacterial Agents; Clay; Colloids; Kaolin; Minerals; Oceans and Seas; Oxytetracycline; Sodium Chloride; Soil

Accurate determination of clay minerals can be challenging due to the natural occurrence of interlayered phases, i.e., layers of different clay species such as illite and smectite. The overlap of peaks of the constituent minerals (e.g., illite and smectite), and the similarity of diffraction patterns when not treated with ethylene glycol, hampers identification, especially when the clay content is low. We investigated the occurrence of interlayered illite/smectite in a rock sample from Rodalquilar, Spain, using X-ray diffraction, scanning electron microscopy and reflectance spectroscopy in the short-wave infrared wavelength range. For the first time, a precise determination of interlayered I/S conducted on the extracted clay fraction treated with ethylene glycol using such different approaches was provided. X-ray diffraction results demonstrated the presence of an I/S peak at around 8.4° in the untreated fraction coupled with a peak splitting at 6.7° and 9.4° 2θ when solvated with ethylene glycol. While spectroscopy indicated the occurrence of interlayered structures as a mixture of the two constituent minerals, the results of X-ray analysis showed that the interlayered clay consisted of two discrete phases (illite and smectite). The two discrete phases were observed in both the whole rock analysis and in the extracted clay fraction. This study shows that X-ray diffraction and validation with a scanning electron microscope is a mandatory, integrating tool for detecting interlayered phases since reflectance spectroscopy alone cannot be used to differentiate between interlayered clay minerals and non-interlayered mixtures. This work highlights the limits and advantages of three sensors (X-ray diffraction, scanning electron microscopy and reflectance spectroscopy) to investigate clay mixtures and interlayering, representing a significant contribution to confidence in the interpretation of interlayered clays, this being essential in mineral exploration and prospecting.

Topics: Clay; Ethylene Glycols; Minerals; Silicates; Spectrum Analysis

The adsorption of thallium (Tl) onto phyllosilicate minerals plays a critical role in the retention of Tl in soils and sediments and the potential transfer of Tl into plants and groundwater. Especially micaceous minerals are thought to strongly bind monovalent Tl(I), in analogy to their strong binding of Cs. To advance the understanding of Tl(I) adsorption onto phyllosilicate minerals, we studied the adsorption of Tl(I) onto Na- and K-saturated illite and Na-saturated smectite, two muscovites, two vermiculites and a naturally Tl-enriched soil clay mineral fraction. Macroscopic adsorption isotherms were combined with the characterization of the adsorbed Tl by X-ray absorption spectroscopy (XAS). In combination, the results suggest that the adsorption of Tl(I) onto phyllosilicate minerals can be interpreted in terms of three major uptake paths: (i) highest-affinity inner-sphere adsorption of dehydrated Tl

Topics: Adsorption; Aluminum Silicates; Cesium; Clay; Minerals; Silicates; Siloxanes; Soil; Thallium

Microplastics are widely detected in the soil-groundwater environment, which has attracted more and more attention. Clay mineral is an important component of the porous media contained in aquifers. The transport experiments of polystyrene nanoparticles (PSNPs) in quartz sand (QS) mixed with three kinds of clay minerals are conducted to investigate the effects of kaolinite (KL), montmorillonite (MT) and illite (IL) on the mobility of PSNPs in groundwater. Two-dimensional (2D) distributions of DLVO interaction energy are calculated to quantify the interactions between PSNPs and three kinds of clay minerals. The critical ionic strengths (CIS) of PSNPs-KL, PSNPs-MT and PSNPs-IL are 17.0 mM, 19.3 mM and 21.0 mM, respectively. Experimental results suggest KL has the strongest inhibition effect on the mobility of PSNPs, followed by MT and IL. Simultaneously, the change of ionic strength can alter the surface charge of PSNPs and clay minerals, thus affecting the interaction energy. Experimental and model results indicate both the deposition rate coefficient (k) and maximum deposition (S

Topics: Bentonite; Clay; Groundwater; Kaolin; Microplastics; Minerals; Plastics; Polystyrenes; Quartz; Sand; Soil

Elucidating the mechanisms of heavy metal (HM) adsorption on clay minerals is key to solving HM pollution in soil. In this study, the adsorption of four HM atoms (As, Cd, Cr, and Hg) on the illite(001) surface was investigated using density functional theory calculations. Different adsorption configurations were investigated and the electronic properties (i.e., adsorption energy (E

Topics: Adsorption; Cadmium; Clay; Environmental Pollution; Mercury; Metals, Heavy; Minerals; Soil; Soil Pollutants

The purpose of this study was to analyze the effects of illite/smectite clay (I/S) on lignocellulosic degradation and humification process via metagenomics analysis during cattle manure composting. The test group (TG) with 10% I/S and the reference group (RG) were established. The results indicated that the addition of I/S made the degradation rate of cellulose, hemicellulose and lignin in TG (1.56%, 29.01%, 19.95%) was higher than that in RG (1.16%, 17.24%, 13.14%). Compared with RG, the abundance values of AA2, AA10, GH1 and GH10 in TG increased by 15.18%, 29.28%, 31.08%, 21.65%, respectively. Meanwhile, humic substance (HS) content was increased by 3.49% and 7.16% during RG and TG composting. Furthermore, the microbial community in TG changed, in which the relative abundance of Actinobacteria increased and Proteobacteria decreased. Redundancy analysis (RDA) showed that the temperature was positively correlated with the abundance of AA2, AA10, GH1 and GH10, whereas the organic matter content was negatively correlated. Overall, adding I/S to the composting could stimulate microbial activity, promote the degradation of lignocellulose and humification process.

Topics: Animals; Cattle; Clay; Composting; Lignin; Manure; Metagenomics; Minerals; Silicates; Soil

The aim of this study was to use metagenomics to investigate how Illite/smectite clay (I/S) affected Auxiliary Activities (AA1, AA2, AA3) thereby enhancing lignin decomposition and humification. Metagenomics analysis illustrated that the abundances of AA1, AA2, AA3 in test group (TG) with 10% I/S were 28.98%, 15.18%, 14.36% higher than that in reference group (RG), respectively. Meanwhile, I/S greatly boosted the efficiency of lignin degradation (17.96%) and humus formation (7.16%) compared with RG (13.10%, 3.49%). Furthermore, Actinobacteria was the microorganism with the greatest contribution in RG and TG to secreting AA1 (41.12%, 57.37%), AA2 (62.42%, 65.28%), AA3 (47.04%, 55.47%). Redundancy analysis (RDA) demonstrated that I/S could make the laccase encoding gene-AA1 contribute more to HS formation relative to AA2 and AA3. In conclusion, applying I/S in cattle manure composting effectively improved the abundance, bioavailability of lignin degradation functional gene enzymes and the composting efficiency.

Topics: Animals; Cattle; Clay; Composting; Ecosystem; Laccase; Lignin; Manure; Metagenomics; Minerals; Silicates; Soil

The mineral composition and surface physico-chemical properties, i.e., specific surface area (SSA), cation exchange capacity (CEC), and surface charge of recent sediments and their submicron mineral fractions from different sedimentological environments of the Eastern Adriatic were investigated. The influence of organic matter on these properties was also investigated. It was shown that illite and mixed-layered clay minerals (MLCM) were ubiquitous and showed no size-related preferences while the occurrence of smectites, chlorites, and kaolinites varied. The smectites content increased and the chlorites decreased slightly with decreasing particle size. The sediments from the carbonate-rich environment contained no smectites or chlorites and had the highest kaolinite content. For the first time, in the recent sediments of the Adriatic Sea the poorly- and the well-crystallised kaolinite (Kl and Kl

Topics: Calcium Carbonate; Cations; Clay; Environmental Monitoring; Geologic Sediments; Italy; Kaolin; Lakes; Minerals; Surface Properties; Water Pollutants, Chemical

Clay minerals abound in sedimentary formations and the interaction of reservoir gases with their submicron features have direct relevance to many geoenergy applications. The quantification of gas uptake over a broad range of pressures is key toward assessing the significance of these physical interactions on enhancing storage capacity and gas recovery. We report a systematic investigation of the sorption properties of three source clay minerals-Na-rich montmorillonite (SWy-2), illite-smectite mixed layer (ISCz-1), and illite (IMt-2)-using CO

Topics: Adsorption; Aluminum Silicates; Carbon Dioxide; Clay; Minerals; Silicates

The retention of radioactive cesium (Cs) in soil is significantly related to the types of clay minerals, while the weathering process affects the irreversible adsorption sites in clay minerals. In this study, the effect of weathering (exposure duration of Cs and repeated wetting and drying cycles) on fractionation of Cs in soils was investigated using fractionation analysis by the sequential extraction. The residual fraction of Cs increased slowly with exposure time but increased rapidly by repeated wetting and drying cycles. XRD analysis shows that a 1.43 nm of interlayer size for vermiculite is shortened to 1.00 nm, i.e., similar to that of illite. The change implies the potential that the structure of expandable clay minerals is transformed to the non-expandable structure by weathering process after Cs retention. Based on the result, the residual fraction of Cs, most stable form of Cs in the soil, reached relatively rapidly to a maximum. However, the process is much slower kinetically in the field because the bench-scale weathering process used in this study is more aggressive. This study implies that Cs fractionations in the soil are converted into a more stable fraction by weathering processes in the soil. Therefore, Cs removal should be conducted as soon as possible after accidental release of Cs in an environmental side.

Topics: Adsorption; Aluminum Silicates; Cesium Radioisotopes; Chemical Fractionation; Clay; Minerals; Soil; Soil Pollutants, Radioactive; Wettability

Radiocesium is well-known to be stabilized by clay minerals in soils, while volcanic soils could typically be poor in micaceous clays that fix

Topics: Aluminum Silicates; Cesium Radioisotopes; Clay; Forests; Fukushima Nuclear Accident; Japan; Minerals; Radiation Monitoring; Soil; Soil Pollutants, Radioactive

In this study, microcystin-LR (MCLR) interactions with three representative silicate clays were studied using equilibrium batch experiments in order to provide insight into the role of clays on determining MCLR fate. The three tested clay minerals (kaolinite, montmorillonite and illite), saturated with sodium or calcium ions, were equilibrated with MCLR across a range of toxin concentrations at pH 5, 7 or 9. The results were fit to Freundlich and linear isotherm models, with the linear isotherm fits deemed most appropriate. In general, adsorption of MCLR was greater in the systems with Ca than in those with Na, however, regardless of the cation present, montmorillonite had the highest adsorption affinity for MCLR. Furthermore, except for Ca-montmorillonite, MCLR adsorption decreased with increasing pH. The pH-dependence of adsorption suggests the polar groups of MCLR, carboxylate associated with the glutamic acid and methylaspartic acid groups and amine associated with the arginine group, were more important in determining MCLR interactions with clays than the nonpolar ADDA group. Increased adsorption in systems enriched with calcium suggests Ca modified the clay interfacial properties and the availability of MCLR groups in a manner that increased MCLR affinity. Overall, the results suggest clays are capable of adsorbing MCLR from the aqueous phase, particularly at low pH and when saturated with Ca

Topics: Adsorption; Bentonite; Binding Sites; Calcium; Clay; Hydrogen-Ion Concentration; Kaolin; Marine Toxins; Microcystins; Minerals; Silicates; Sodium

The picloram (PCM) adsorption on nontronite, illite and kaolinite was studied at pH 3, 5 and 7. The adsorption isotherms had well-fitted to Langmuir and Freundlich models equations. The interactions of PCM with the clay mineral surfaces exhibited an anionic profile adsorption, with a decrease in adsorption when the pH increases. The PCM adsorption capacity increases in the following order: kaolinite < illite < nontronite. The X-ray diffraction (XRD) analysis of PCM-clay samples revealed that the picloram molecule does not enter into the clays basal space. The interaction of PCM with clays surface sites through nitrogen of the pyridine ring was confirmed by X-ray photoelectron spectroscopy (XPS). Due to the anionic form of PCM, the adsorption onto the external and edges surface sites of the clay minerals was proposed.

Topics: Adsorption; Clay; Herbicides; Hydrogen-Ion Concentration; Kaolin; Minerals; Photoelectron Spectroscopy; Picloram; X-Ray Diffraction

Iron-bearing clays are ubiquitously distributed as mineral dusts in the atmosphere. Bromophenols were reported as the major products from thermal decomposition of the widely used brominated flame retardants (BFRs). However, little information is available for the reactivity of iron associated with mineral dusts to interact with the atmospheric bromophenols and the subsequent toxic effects. Herein, three common clay minerals (montmorillonite, illite and kaolinite) were used to simulate mineral dusts, and the reactions with gaseous 2-bromophenol were systematically investigated under environmentally relevant atmospheric conditions. Our results demonstrate that structural Fe(III) in montmorillonite and Fe(III) from iron oxide in illite mediated the dimerization of 2-bromophenol to form hydroxylated polybrominated biphenyl and hydroxylated polybrominated diphenyl ether. The surface reaction is favored to occur at moisture environment, since water molecules formed complex with 2-bromophenol and the reaction intermediates via hydrogen bond to significantly lower the reaction energy and promote the dimerization reaction. More importantly, the formed dioxin-like products on clay mineral dust increased the toxicity of the particles to A549 lung cell by decreasing cell survival and damaging cellular membrane and proteins. The results of this study indicate that not only mineral dust itself but also the associated surface reaction should be fully considered to accurately evaluate the toxic effect of mineral dust on human health.

Topics: A549 Cells; Air Pollutants; Atmosphere; Bentonite; Cell Survival; Clay; Dust; Ferric Compounds; Halogenated Diphenyl Ethers; Humans; Kaolin; Minerals; Phenols; Surface Properties; Water

Today the terrestrial surface drives biogeochemical cycles on Earth through chemical weathering reactions mediated by the biological influence of soils. Prior to the expansion of life on to land, abiotic weathering may have resulted in different boundary conditions affecting the composition of the biosphere. Here we show a striking difference in weathering produced minerals preserved in the Mesoproterozoic Velkerri Formation. While the bulk chemistry and mineralogy is dominated by illite similar to many modern mudstones, application of a novel microbeam technology reveals that the initial detrital minerals were composed of mica (28%) and feldspar (45%) with only a trace amount (<2%) of typical soil formed clay minerals. The majority of illite and the high Al

Topics: Aluminum Silicates; Australia; Chemical Phenomena; Chemistry, Physical; Clay; Environmental Monitoring; Geological Phenomena; Geology; Minerals; Oceans and Seas; Potassium Compounds; Soil; Trace Elements; Weather

This field study aims to identify the performance and mechanisms of red soil amelioration and heavy metal immobilization by a multi-element mineral amendment (MMA) mainly containing a mixture of zeolites (laumontite and gismondine), montmorillonite, gehlenite, grossular and calcium silicate powder. The results indicated that the acidity of red soil was neutralized, and the soil EC, CEC, and content of montmorillonite and illite were increased after application of MMA, improving the soil fertility as well as the ability of heavy metals immobilization. The high amounts and reactivity of dissolved and colloidal Fe provided by the ferralsol (red soil) combined with the abundant available Si, Ca, Mg, Na and K supplied by MMA, readily destabilizes kaolinite and facilitates the formation of 2:1 type clay minerals. Meanwhile, the application of MMA was effective in reducing the bioavailability of soil heavy metals due to the activated mineralogical compositions of MMA as well as the increase of pH and 2:1 type clay minerals in the soil, which significantly decreased the up-taking and accumulation of Cd, Pb, Cr and Hg in lettuce tissues (p < 0.05). Compared with the untreated soil, the plant height, the total yield and content of vitamin C in the edible parts of lettuce in MMA-treated soil was increased by 7.6%, 23.6%, and 12.8%, respectively. These results showed that MMA could be a promising amendment for red soil amelioration and heavy metal immobilization.

Topics: Bentonite; Biological Availability; Clay; Environmental Restoration and Remediation; Metals, Heavy; Minerals; Soil; Soil Pollutants; Zeolites

Fate and transport of engineered nanoscale titanium dioxide (nTiO

Topics: Aluminum Silicates; Clay; Colloids; Drug Stability; Humic Substances; Minerals; Nanoparticles; Static Electricity; Titanium; Water

The commonly used theory to describe the normal Brownian mode of field-flow fractionation (FFF) assumes the particles to be point masses and hence the shape is ignored. Beckett and Giddings extended this theory to include the effect of thin rods and discs being forced very close to the accumulation wall. By including the decrease in the entropy this causes, they derived new expressions for the retention of such nonspherical particles in FFF. The steric-entropic theory predicts that when the sample cloud thickness is less than the major dimension of the rods or discs then particles elute earlier than predicted by the Brownian mode theory. This leads to an underestimation of the buoyant mass and equivalent spherical diameter calculated from FFF data. In this paper we report for the first time experimental data for the retention of thin illite particles in centrifugal FFF that agrees well with these steric-entropic predictions. Not only do the size distributions calculated using the Brownian mode theory shift to lower size when the field is increased but the shift in the retention ratio of the peak maxima of the FFF fractograms could be predicted fairly accurately by the steric-entropic equations.

Topics: Aluminum Silicates; Chemistry Techniques, Analytical; Clay; Fractionation, Field Flow; Minerals; Particle Size

Topics: Adsorption; Aluminum Silicates; Clay; Kaolin; Minerals; Molecular Weight; Organic Chemicals; Water

The widespread use of cadmium (Cd)-containing organic fertilizers is a source of heavy metal inputs to agricultural soils in suburban areas. Therefore, the research and development of new materials and technologies for the remediation of Cd-contaminated soil is of great significance and has the potential to guarantee the safety of agricultural products and the protection of human health. We performed pot experiments to determine the potential of combined amendments of illite/smectite (I/S) clay with bone chars for the remediation of Cd-contaminated agricultural soils in a suburban area of Beijing, China. The results showed that both diethylene triamine pentaacetic acid (DTPA)-extractable Cd in soil and the Cd in Brassica chinensis were significantly decreased by the application of 1, 2, or 5% combined amendments with various I/S and bone char (BC) ratios. The higher proportions of BC used in the combined amendments resulted in a better immobilization of soil Cd. The application of the 5% amendment that combined I/S with either pig or cattle BC resulted in the best immobilization. All of the combined amendments, regardless of the composition and ratio of the components, had no negative effects on the growth of B. chinensis. Therefore, it was concluded that combined amendments of I/S and BC have a good potential for remediating Cd-contaminated soils.

Topics: Agriculture; Animals; Beijing; Biological Products; Brassica; Cadmium; Clay; Environmental Restoration and Remediation; Fertilizers; Minerals; Silicates; Soil; Soil Pollutants

The presence and persistency of pharmaceuticals and personal care products (PPCPs) in the environment attracted great attention recently. Among them, antibiotics and pain-killers accounted for a large quantity. Although many works were devoted to the investigation of their removal in wastewater treatment processes, most of the PPCPs studied were of cationic nature. The net repulsive interactions between anionic PPCPs and negatively charged sorbents make them difficult to be removed in wastewater treatment. In this study, 2:1 clay minerals illite and montmorillonite (MMT) were modified with different amounts of cationic surfactant cetyltrimethylammoium bromide (CTAB). The types and sites of interactions between the surfactant-modified clays and the anionic drug diclofenac (DC) were investigated. The uptake of DC on the modified clays was controlled by the CTAB loading level and its surface configuration on the clays. The adsorption sites of DC were limited to the external surfaces of modified illite due to its non-swelling nature. On the contrary, both the external and interlayer sites were available for the adsorption of DC on modified MMT. A CTAB bilayer formation resulted in significant increase in DC adsorption due to the formation of extensive admicelles. FTIR results showed participation of the benzene ring, NH, and CH

Topics: Aluminum Silicates; Bentonite; Cetrimonium; Cetrimonium Compounds; Clay; Diclofenac; Drug Residues; Micelles; Microscopy, Electron, Scanning; Minerals; Models, Molecular; Surface-Active Agents; Waste Disposal, Fluid

Discoveries associated with antibacterial activity of hydrated clays necessitate assessments of in vivo efficacy, practical use and safety. Surface properties of clays can lead to variations in the composition and abundance of bound compounds or ions, thus affecting antibacterial activity. Since exchangeable metal ions released from the clay surface are responsible for in vitro antibacterial activity, we evaluated the in vivo antibacterial efficacy of four natural clays (one illite clay, two montmorillonite clays and one kaolinite clay) and three ion-exchanged, antibacterial clays against superficial, cutaneous meticillin-resistant Staphylococcus aureus (MRSA) infections in mice. Superficial, cutaneous wounds on the back of SKH1-Elite mice were generated and subsequently infected with MRSA. Following twice daily applications of a hydrated clay poultice to infected wounds for 7  days, we observed significant differences in the in vivo antibacterial efficacy between different types of clays. The natural and ion-exchanged illite clays performed best, as measured by bacterial load, inflammatory response and gross wound morphology with significant decreases in bacterial viability and dermatitis. Topical application of kaolinite clay was the least effective, resulting in the lowest decrease in bacterial load and exhibiting severe dermatitis. These data suggest that specific types of clays may offer a complementary and integrative strategy for topically treating MRSA and other cutaneous infections. However, since natural clays exhibit in vitro antibacterial variability and vary vastly in surface chemistries, adsorptive/absorptive characteristics and structural composition, the properties and characteristics of illite clays could aid in the development of standardized and customized aluminosilicates for topical infections.

Topics: Aluminum Silicates; Animals; Anti-Bacterial Agents; Bacterial Load; Chemical Phenomena; Clay; Disease Models, Animal; Drug Resistance, Multiple, Bacterial; Female; Inflammation; Methicillin-Resistant Staphylococcus aureus; Mice; Minerals; Skin Diseases, Bacterial; Wound Infection

The sorption of radium 226 ((226)Ra) on different clay materials (bentonite, illite and a mixture of bentonite-illite) was studied. Clay materials are used in the construction of disposal pits for technically enhanced naturally occurring radioactive materials (TENORM) wastes (i.e., contaminated soil and sludge) generated by the oil and gas industry operations. Experimental conditions (pH, clay materials quantity, and activity concentrations of (226)Ra) were changed in order to determine the optimal state for adsorption of (226)Ra. The results showed that the concentration of adsorbed (226)Ra on clay materials increased with time to reach an equilibrium state after approximately 5 h. More than 95 % of the radium was adsorbed. The mixture of bentonite-illite (1/9) exhibited the greatest adsorption of radium under all experimental conditions.

Topics: Absorption, Physicochemical; Adsorption; Aluminum Silicates; Bentonite; Clay; Minerals; Models, Chemical; Radium; Sewage; Water Pollutants, Radioactive

Clay minerals, charcoal and metal oxides are essential parts of the soil matrix and strongly influence the formation of biogeochemical interfaces in soil. We investigated the role of these parental materials for the development of functional microbial guilds using the example of alkane-degrading bacteria harbouring the alkane monooxygenase gene (alkB) in artificial mixtures composed of different minerals and charcoal, sterile manure and a microbial inoculum extracted from an agricultural soil. We followed changes in abundance and community structure of alkane-degrading microbial communities after 3 and 12 months of soil maturation and in response to a subsequent 2-week plant litter addition. During maturation we observed an overall increasing divergence in community composition. The impact of metal oxides on alkane-degrading community structure increased during soil maturation, whereas the charcoal impact decreased from 3 to 12 months. Among the clay minerals illite influenced the community structure of alkB-harbouring bacteria significantly, but not montmorillonite. The litter application induced strong community shifts in soils, maturated for 12 months, towards functional guilds typical for younger maturation stages pointing to a resilience of the alkane-degradation function potentially fostered by an extant 'seed bank'.

Topics: Alkanes; Aluminum Silicates; Bacteria; Charcoal; Clay; Metals; Minerals; Soil; Soil Microbiology; Soil Pollutants

Based on the laser particle size and X-ray diffraction (XRD) analysis, 28 sediment samples collected from the inshore region of the Yellow River estuary in October 2013 were determined to discuss the influence of long-term implementation of the flow-sediment regulation scheme (FSRS, initiated in 2002) on the distributions of grain size and clay components (smectite, illite, kaolinite and chlorite) in sediments. Results showed that, after the FSRS was implemented for more than 10 years, although the proportion of sand in inshore sediments of the Yellow River estuary was higher (average value, 23.5%) than those in sediments of the Bohai Sea and the Yellow River, silt was predominated (average value, 59.1%) and clay components were relatively low (average value, 17.4%). The clay components in sediments of the inshore region in the Yellow River estuary were close with those in the Yellow River. The situation was greatly changed due to the implementation of FSRS since 2002, and the clay components were in the order of illite > smectite > chlorite > kaolinite. This study also indicated that, compared to large-scale investigation in Bohai Sea, the local study on the inshore region of the Yellow River estuary was more favorable for revealing the effects of long-term implementation of the FSRS on sedimentation environment of the Yellow River estuary.

Topics: Aluminum Silicates; China; Clay; Estuaries; Geologic Sediments; Kaolin; Minerals; Rivers; X-Ray Diffraction

Enteropathogens released into the environment can represent a serious risk to public health. Soil clay content has long been known to have an important effect on enteropathogen survival in soil, generally enhancing survival. However, clay mineral composition in soils varies, and different clay minerals have specific physiochemical properties that would be expected to impact differentially on survival. This work investigated the effect of clay materials, with a predominance of a particular mineral type (montmorillonite, kaolinite, or illite), on the survival in soil microcosms over 96 days of Listeria monocytogenes, Salmonella Dublin, and Escherichia coli O157. Clay mineral addition was found to alter a number of physicochemical parameters in soil, including cation exchange capacity and surface area, and this was specific to the mineral type. Clay mineral addition enhanced enteropathogen survival in soil. The type of clay mineral was found to differentially affect enteropathogen survival and the effect was enteropathogen-specific.

Topics: Aluminum Silicates; Bentonite; Clay; Escherichia coli O157; Ireland; Kaolin; Listeria monocytogenes; Minerals; Salmonella enterica; Soil; Soil Microbiology; Survival Analysis; X-Ray Diffraction

Cesium adsorption onto Illite has been widely studied, because this clay is especially relevant for Cs migration-retention in the environment. The objective of this study is to analyze how Cs adsorption onto Illite is affected by structural changes produced by the presence of different exchangeable cations--and specifically interlayer collapse. Cs sorption isotherms were carried out with Illite previously exchanged with Na, K, or Ca, at a broad enough range of ionic strength, for the determination of the possible affect of the electrolyte on the structure of Illite. In the presence of Ca, the maximum sorbed Cs was unexpectedly high (900 mequiv · kg(-1)) given the cationic exchange capacity commonly accepted for Illite (near 200 mequiv · kg(-1)). This was explained by the expansion of Illite layers (decollapse) induced by large hydrated cations such as Ca(2+) that may facilitate cation uptake--especially Cs(+), which is a highly selective cation. In the presence of Ca (and most probably of other divalent cations), Cs accessibility to exchange positions is increased. Both experimental evidence and the modeling of Cs sorption onto Illite supported the hypothesis of decollapse. Our results demonstrate the requirement of accounting for Illite decollapse especially for high Cs loadings, because of the potential prediction errors for its migration. Ignoring the Illite decollapse could lead the biased estimation of selectivity coefficients and consequently the erroneous prediction of sorption/migration behavior of Cs, and possibly other contaminants, in the environment.

Topics: Adsorption; Aluminum Silicates; Cesium; Clay; Minerals; Models, Chemical

Sorption to the phyllosilicate clay minerals Illite, kaolinite, and bentonite has been studied for a wide variety of organic cations using a flow-through method with fully aqueous medium as the eluent. Linear isotherms were observed at concentrations below 10% of the cation-exchange capacity (CEC) for Illite and kaolinite and below 1 mmol/kg (<1% CEC) for bentonite. Sorption to clays was strongly influenced by the electrolyte composition of the eluent but with a consistent trend for a diverse set of compounds on all clays, thus allowing for empirical correction factors. When sorption affinities for a given compound to a given clay are normalized to the CEC of the clay, the differences in sorption affinities between clays are reduced to less than 0.5 log units for most compounds. Although CEC-normalized sorption of quaternary ammonium compounds to clay was up to 10-fold higher than CEC-normalized sorption to soil organic matter, CEC-normalized sorption for most compounds was comparable between clays and soil organic matter. The clay fraction is thus a potentially relevant sorption phase for organic cations in many soils. The sorption data for organic cations to clay showed several regular trends with molecular structure but also showed quite a few systematic effects that we cannot explain. A model on the basis of the molecular size and charge density at the ionized nitrogen is used here as a tool to obtain benchmark values that elucidate the effect of specific polar moieties on the sorption affinity.

Topics: Adsorption; Aluminum Silicates; Bentonite; Cations; Clay; Electrolytes; Hydrophobic and Hydrophilic Interactions; Kaolin; Minerals; Molecular Weight; Organic Chemicals; Quaternary Ammonium Compounds; Salts; Soil Pollutants; Static Electricity

Clay minerals are ubiquitous in soils, sediments, and sedimentary rocks and could coexist with sulfate-reducing bacteria (SRB) in anoxic environments, however, the interactions of clay minerals and SRB are not well understood. The objective of this study was to understand the reduction rate and capacity of structural Fe(III) in dioctahedral clay minerals by a mesophilic SRB, Desulfovibrio vulgaris and the potential role in catalyzing smectite illitization. Bioreduction experiments were performed in batch systems, where four different clay minerals (nontronite NAu-2, mixed-layer illite-smectite RAr-1 and ISCz-1, and illite IMt-1) were exposed to D. vulgaris in a non-growth medium with and without anthraquinone-2,6-disulfonate (AQDS) and sulfate. Our results demonstrated that D. vulgaris was able to reduce structural Fe(III) in these clay minerals, and AQDS enhanced the reduction rate and extent. In the presence of AQDS, sulfate had little effect on Fe(III) bioreduction. In the absence of AQDS, sulfate increased the reduction rate and capacity, suggesting that sulfide produced during sulfate reduction reacted with the phyllosilicate Fe(III). The extent of bioreduction of structural Fe(III) in the clay minerals was positively correlated with the percentage of smectite and mineral surface area of these minerals. X-ray diffraction, and scanning and transmission electron microscopy results confirmed formation of illite after bioreduction. These data collectively showed that D. vulgaris could promote smectite illitization through reduction of structural Fe(III) in clay minerals.

Topics: Aluminum Silicates; Clay; Desulfovibrio; Ferric Compounds; Geologic Sediments; Iron; Microscopy, Electron, Scanning; Microscopy, Electron, Transmission; Minerals; Oxidation-Reduction; Silicates; Sulfates; X-Ray Diffraction

The surface properties and functionality of an illite-containing clay mineral in alkaline solutions containing increasing quantities of calcium hydroxide were investigated using FTIR monitored pyridine adsorption at various temperatures. Results showed that the binding behavior of electron donor pyridine molecules to illite platelets is mostly governed by electron acceptor sites located at the edges of the clay particles. The binding of bulky hydrated calcium ions at the surface of the illite platelets decreases the surface area of illite. Moderate thermal treatments up to 450°C do not affect the structure of the clay mineral but strongly decrease the number of Lewis and Brönsted sites available at the edges of the clay platelets.

Topics: Adsorption; Aluminum Silicates; Binding Sites; Calcium; Calcium Compounds; Calcium Hydroxide; Clay; Electrons; Hot Temperature; Ions; Minerals; Oxides; Pyridines; Spectroscopy, Fourier Transform Infrared; Surface Properties

An extensive set of column experiments was performed with freshly harvested Cryptosporidium parvum oocysts to evaluate the effects of solution chemistry, surface coatings, interactions with other suspended particles, and pore fluid velocity on the fate and transport of this widely occurring waterborne pathogen in sandy porous media. We synthesized our data set with a comprehensive literature survey of similar experiments, to compute attachment (collision) efficiencies (α) used in colloid filtration theory (CFT) using three models for the single collector efficiency (η) across a wide range of experimental conditions. Most prior experiments have observed the transport of surface-treated, sterile C. parvum oocyst in porous media. Our column data confirm for freshly harvested oocysts that the presence of iron coatings on the sand medium and the presence of suspended illite clay drastically enhance oocyst deposition. Increasing ionic strength and decreasing pH also systematically enhance the attachment efficiency. Attachment efficiency decreases only at a very high ionic strength, most likely as a result of steric repulsion and possibly other changes in oocyst surface properties. Attachment efficiencies vary with fluid flow rate but without showing specific trends. We found that the computed attachment efficiency across all reported experiments could be reliably estimated using a regression model based on parameters related to ionic strength and pH. The regression model performed better with the Nelson-Ginn η model and Tufenkji-Elimelech η model than with the Rajagopalan-Tien η model. When CFT is used in environmental assessments, the proposed regression model provides a practical estimator for attachment efficiencies of C. parvum oocyst deposition in porous media for a variety of environmental conditions unfavorable to attachment.

Topics: Adsorption; Aluminum Silicates; Clay; Cryptosporidiosis; Cryptosporidium parvum; Ferric Compounds; Humans; Minerals; Oocysts; Osmolar Concentration; Porosity; Surface Properties

Natural clays have been used in ancient and modern medicine, but the mechanism(s) that make certain clays lethal against bacterial pathogens has not been identified. We have compared the depositional environments, mineralogies, and chemistries of clays that exhibit antibacterial effects on a broad spectrum of human pathogens including antibiotic resistant strains. Natural antibacterial clays contain nanoscale (<200 nm), illite-smectite and reduced iron phases. The role of clay minerals in the bactericidal process is to buffer the aqueous pH and oxidation state to conditions that promote Fe(2+) solubility. Chemical analyses of E. coli killed by aqueous leachates of an antibacterial clay show that intracellular concentrations of Fe and P are elevated relative to controls. Phosphorus uptake by the cells supports a regulatory role of polyphosphate or phospholipids in controlling Fe(2+). Fenton reaction products can degrade critical cell components, but we deduce that extracellular processes do not cause cell death. Rather, Fe(2+) overwhelms outer membrane regulatory proteins and is oxidized when it enters the cell, precipitating Fe(3+) and producing lethal hydroxyl radicals.

Topics: Aluminum Silicates; Anti-Bacterial Agents; Clay; Escherichia coli; Hydrogen-Ion Concentration; Hydroxyl Radical; Iron; Microscopy, Electron, Transmission; Minerals; Oxidation-Reduction; Phosphorus; Silicates

To investigate the mechanisms of tritium persistence in clay minerals, three types of clay soils (montmorillonite, kaolinite and illite) and tritiated water were used in this study to conduct the tritium sorption tests and the other related tests. Firstly, the ingredients, metal elements and heat properties of clay minerals were studied with some instrumental analysis methods, such as ICP and TG. Secondly, with a specially designed fractionation and condensation experiment, the adsorbed water, the interlayer water and the structural water in the clay minerals separated from the tritium sorption tests were fractionated for investigating the tritium distributions in the different types of adsorptive waters. Thirdly, the location and configuration of tritium adsorbed into the structure of clay minerals were studied with infrared spectrometry (IR) tests. And finally, the forces and mechanisms for driving tritium into the clay minerals were analyzed on the basis of the isotope effect of tritium and the above tests. Following conclusions have been reached: (1) The main reason for tritium persistence in clay minerals is the entrance of tritium into the adsorbed water, the interlayer water and the structural water in clay minerals. The percentage of tritium distributed in these three types of adsorptive water are in the range of 13.65% - 38.71%, 0.32% - 5.96%, 1.28% - 4.37% of the total tritium used in the corresponding test, respectively. The percentages are different for different types of clay minerals. (2) Tritium adsorbed onto clay minerals are existed in the forms of the tritiated hydroxyl radical (OT) and the tritiated water molecule (HTO). Tritium mainly exists in tritiated water molecule for adsorbed water and interlayer water, and in tritiated hydroxyl radical for structural water. (3) The forces and effects driving tritium into the clay minerals may include molecular dispersion, electric charge sorption, isotope exchange and tritium isotope effect.

Topics: Adsorption; Aluminum Silicates; Bentonite; Clay; Environmental Monitoring; Environmental Pollutants; Kaolin; Minerals; Porosity; Tritium

Clay-humic substance complexes play a major role in controlling the mobility of toxic metals in contaminated soils. However, our understanding of the underlying mechanisms is limited. Binding site analysis of clay and clay-mineral-humic composites, in this study, revealed an enhanced surface reactivity for the clay surface by the sorbed humic substances. Kaolinite and illite had three binding sites with pK(a) values ranging from ∼4.5 to 9.6 at Ca(2+) concentrations of 0.01 and 0.1 M respectively. In the presence of peat humic acid (PHA), four or five binding sites were observed for humics sorbed kaolinite surface at Ca(2+) concentrations of 0.01 and 0.1 M respectively. pK(a) values ranged from ∼4.4 to 9.6 for humic acid concentration of 0.01 and 0.1 mg/mL. For illite, four or five binding sites were found with pK(a)s ranging from ∼4.1 to 9.4. From zeta potential measurements of PHA-kaolinite or PHA-illite suspensions, the already negative potential decreased by 30 mV from pH 4 to 7, and by 10 mV for pH values greater than 7. For illite the initial negative surface potential decreased by 15 mV up to a pH of 9. Above this pH, the potential decrease diminished to 2 or 5 mV. These changes in surface potential confirm the adsorption of PHA to the clay mineral surface. FTIR measurements of clay samples were able to identify the kaolinite and illite phases. In addition, FTIR absorption bands found in the range of 1950-1800 cm(-1), suggest the interaction of PHA with kaolinite and illite surfaces. The results of this study indicate that the sorption of humic substances increases the availability of clay surface functional groups for deprotonation and potential sorption of toxic metal cations.

Topics: Adsorption; Aluminum Silicates; Binding Sites; Calcium; Clay; Humic Substances; Kaolin; Minerals; Surface Properties

Physicochemical simulation (pH, electrolytes and temperature) of three physiological media was carried out in order to follow the release of trace elements contained in seven edible clays (mainly kaolinite, illite, muscovite and quartz) collected from the West African countries of Côte d'Ivoire, Guinée and Sénégal. These clays are ingested by pregnant women for diverse reasons that are related to their condition. Simulated oral (6.5

Topics: Africa, Western; Aluminum Silicates; Clay; Diet; Electrolytes; Female; Gastrointestinal Tract; Humans; Hydrogen-Ion Concentration; Kaolin; Minerals; Pica; Pregnancy; Quartz; Soil; Temperature; Trace Elements

Adsorption of three surfactants of different nature, Triton X-100 (TX100) (non-ionic), sodium dodecylsulphate (SDS) (anionic) and octadecyltrimethylammonium bromide (ODTMA) (cationic) by four layered (montmorillonite, illite, muscovite and kaolinite) and two non-layered (sepiolite and palygorskite) clay minerals was studied. The objective was to improve the understanding of surfactant behaviour in soils for the possible use of these compounds in remediation technologies of contaminated soils by toxic organic compounds. Adsorption isotherms were obtained using surfactant concentrations higher and lower than the critical micelle concentration (cmc). These isotherms showed different adsorption stages of the surfactants by the clay minerals, and were classified in different subgroups of the L-, S- or H-types. An increase in the adsorption of SDS and ODTMA by all clay minerals is observed up to the cmc of the surfactant in the equilibrium solution is reached. However, there was further TX100 adsorption when the equilibrium concentration was well above the cmc. Adsorption constants from Langmuir and Freundlich equations (TX100 and ODTMA) or Freundlich equation (SDS) were used to compare adsorption of different surfactants by clay minerals studied. These constants indicated the surfactant adsorption by clay minerals followed this order ODTMA>TX100>>SDS. The adsorption of TX100 and ODTMA was higher by montmorillonite and illite, and the adsorption of SDS was found to be higher by kaolinite and sepiolite. Results obtained show the influence of clay mineral structure and surfactant nature on the adsorption capacity of surfactants by clays, and they indicate the interest to consider the soil mineralogical composition when one surfactant have to be selected in order to establish more efficient strategies for the remediation of soils and water contaminated by toxic organic pollutants.

Topics: Adsorption; Alkanes; Aluminum Silicates; Bentonite; Clay; Kaolin; Magnesium Compounds; Magnesium Silicates; Minerals; Octoxynol; Quaternary Ammonium Compounds; Silicon Compounds; Sodium Dodecyl Sulfate; Soil Pollutants; Spectrum Analysis; Surface-Active Agents

The effect of different rice cultivation periods on the properties of selected soils in alluvial plain were studied in Mazandaran province (north of Iran) in 2004. Soils were sampled form 0, 6, 16, 26 and over 40 years rice cultivation fields. In each treatment three soil profiles and six nearby auger holes were studied. The present study results indicated that continuous rice cultivation have changed soil moisture regime from xeric to aquic, soil color from brown to grayish, surface horizons from mollic to ochric epipedon and soil structure changed from granular or blocky to massive. Therefore, the soil order has changed from Mollisols to Inceptisols. No illuviation and eluviation of clay minerals occurred as a consequence of rice cultivation. X-ray diffraction analysis showed that clay minerals in non-rice cultivated field were illite, vermiculite, montmorillonite, kaolinite and chlorite, but in rice field were illite, montmorillonite, kaolinite and chlorite, respectively. In contrast of montmorillonite, the amount of illite and vermiculite have been decreased by increasing periods of rice cultivation. The pH values of the saturated soil surface in six weeks past plantation have shifted toward neutrality. While Eh value of non-paddy soils were about +90 mv, surface horizons of paddy soils at field conditions had Eh value about +40, -12, -84, -122 mv, respectively. The amounts of organic matter and available Fe, Mn, Zn and Cu were increased whereas available K was decreased in paddy soils.

Topics: Agriculture; Aluminum Silicates; Bentonite; Chlorides; Clay; Hydrogen-Ion Concentration; Iran; Kaolin; Minerals; Oryza; Potassium; Soil; Time Factors; Water; X-Ray Diffraction

Substantial amounts of sulfonamides, ionizable, polar veterinary antimicrobials, may reach the environment by spreading of manure. Sorption to soils and sediments is a crucial but not sufficiently understood process influencing the environmental fate of sulfonamides. Therefore, we investigated sorption of sulfathiazole to clay minerals (montmorillonite, illite) and ferrihydrite for varying pH values and two contact times (1d, 14 d) under sterile conditions. Results were compared to sulfathiazole sorption to organic sorbents. Sulfathiazole sorption to inorganic sorbents exhibited pronounced pH dependence consistent with sorbate speciation and sorbent charge properties. While sulfathiazole cations were most important for sorption to clay minerals, followed by neutral species, ferrihydrite was a specific anion sorbent, showing significant sorption only between pH 5.5-7. Experiments revealed a substantial increase of sorption with time for ferrihydrite (pH 5.5-7) and illite (pH<5.5). Reasons may be disaggregation of clay minerals and, for ferrihydrite, diffusion and sorption of sulfathiazole in micropores. Independent of contact time and pH, sorption to inorganic sorbents was more than an order of magnitude lower than to organic sorbents. This implies that in many topsoils and sediments inorganic sorbents play a minor role. Our results highlight the need to account for contact time and speciation when predicting sulfonamide sorption in the environment.

Topics: Adsorption; Aluminum Silicates; Anti-Infective Agents; Bentonite; Clay; Ferric Compounds; Hydrogen-Ion Concentration; Minerals; Molecular Structure; Sulfathiazole; Sulfathiazoles; Time Factors

The objective of this work was to coat aluminosilicate clays on an inert silica support, and to characterize the properties and stability of the clay-silica coating. Two polymers, polyacrylamide (PAM) and polyvinyl alcohol (PVA), were used to bind kaolinite, illite, and smectite onto silica grains. The clay-polymer composites were studied by X-ray diffraction, FTIR, and electrophoretic mobility. Clay coatings on silica grains were characterized by mass coverage, scanning electron microscopy, specific surface area, and pH stability. Silica sand was successfully coated with clays by using the two polymers, but with PVA, the clay coating had a greater mass coverage and was more stable against pH variations. Less polymer was needed for the clay coating using PVA as compared to using PAM. Clay-polymer complexes and pure clay minerals had similar cation exchange capacities and electrophoretic mobilities, indicating that overall surface charge of the clays was little affected by the polymers. Some decrease in hydrophilicity was observed for illite and smectite when clays where coated with the polymers. The methodology reported here allows the generation of a clay-based porous matrix, with hydraulic properties that can be varied by adjusting the grain size of the inert silica support.

Topics: Acrylic Resins; Adsorption; Aluminum Silicates; Clay; Electrophoresis; Hydrogen-Ion Concentration; Ion Exchange; Kaolin; Microscopy, Electron, Scanning; Minerals; Particle Size; Polyvinyl Alcohol; Silicates; Silicon Dioxide; Spectroscopy, Fourier Transform Infrared; Surface Properties; X-Ray Diffraction

Illite clays are known to have a strong affinity for metallic pollutants in the environment and can be applied as low-cost adsorbents for industrial waste treatment. A crucial factor in the development of such applications, however, is the understanding of the chemical, mineralogical, and colloidal properties of these clays. It is also important to understand the mechanisms involved in the surface adsorption of metals by these adsorbants. In order to study the retention of transition metals on illite clays, we have applied surface characterization techniques such as FPIA, SEM-EDX, XRD, N2 (77 K) adsorption, and FTIR. In addition to these experimental techniques, we have also employed a theoretical model that accounts for the chemistry of transition metal ions, and considers the global retention process to be the sum of several single retention processes. This model adequately fits the experimental data and allows for the speciation of metal retention on illite surfaces. Between pH values of 2.53 and 3.01 the only adsorption processes are the electrostatic sorption of [Cu(H2O)6]2+, and the surface complexation of [Cu(H2O)6]2+ and [Cu(OH)(H2O)5]+ ions. Surface complexation of [Cu(OH)(H2O)5]+ ions increases with pH, overcoming [Cu(H2O)6]2+ retention, and thus contributing to the surface precipitation of Cu(OH)2.

Topics: Adsorption; Aluminum Silicates; Clay; Copper; Microscopy, Electron, Scanning; Minerals; Surface Properties

Humic acids and clays are important soil components that influence the sorption and desorption of organic contaminants; however, it is unclear how humic acids influence the sorption of organic contaminants onto clays and their subsequent desorption. Sorption and desorption of 2,4,6-trichlorophenol (2,4,6-TCP) by and from humic acid-modified K(+)- and Ca(2+)-montmorillonite and -illite were compared with unmodified clays using batch equilibration methods. Commercial humic acid and the humic acid extracted from forest soil were employed in this experiment. The adsorbed amount of 2,4,6-TCP by commercial humic acid was almost twice as large as that adsorbed by the extracted soil humic acid. More 2,4,6-TCP was sorbed onto K(+)- and Ca(2+)-illite than onto K(+)- and Ca(2+)-montmorillonite. K(+) clays were more effective in adsorbing 2,4,6-TCP than Ca(2+) clays. Sorption of 2,4,6-TCP on humic acid-modified Ca(2+)- and K(+)-montmorillonite and -illite increased as compared with unmodified clays. The sorption nonlinearity of 2,4,6-TCP on humic acid-modified Ca(2+)- and K(+)-illite increased remarkably as compared with the unmodified clays. The sorption nonlinearity of 2,4,6-TCP on humic acid-modified Ca(2+)- and K(+)-montmorillonite increased slightly in contrast to unmodified montmorillonites. By comparing sorption and desorption results, we observed hysteresis for all sorbents including humic acids, clays, and humic acid-modified clays. Sorption nonlinearity and hysteresis were dependent on the structure of humic acids. Higher aromaticity of humic acids resulted in greater sorption nonlinearity and desorption hysteresis. In addition, sorption capacity (K(f)') was positively correlated with the humic acid content of the sorbents. These results show that modification of humic acids on clays can not only increase the adsorption ability of clays but also affect the sorption nonlinearity of 2,4,6-TCP, and the desorption hysteresis was probably due to the structural characteristics of humic acids.

Topics: Adsorption; Aluminum Silicates; Bentonite; Calcium; Carbon; Chlorophenols; Clay; Humic Substances; Minerals; Potassium; Soil Pollutants

The effects of ethanol- and methanol-water mixtures on Zn and Cd sorption onto bentonite and illite were investigated at low initial metal concentration (< or =10(-5) M) and low ionic strength (2.5 mM Ca(NO3)2). For all cosolvent fractions, the percent coverage of Zn and Cd to clay minerals was low (<5%) and independent of the solution dielectric constant, epsilon, except for Zn at 10 microM. Cadmium sorption to bentonite and illite was independent of epsilon. Zinc sorption varied significantly between clay types, cosolvent type, and cosolvent fraction. The partitioning of Zn to bentonite increased from 0 to 10% alcohol-water fraction and decreased after 10%. The same pattern was observed for the partitioning of Zn on illite in methanol-water mixtures. In ethanol-water mixtures, Kf for Zn on illite increased continuouslyfrom 0 to 50% ethanol. The decreased partitioning and hence mobility of Zn to bentonite and illite after 10% alcohol (only in methanol-water mixtures for illite) suggests a potential environmental threat resulting from increased transport of this metal in subsurface environments where these cosolvents are present.

Topics: Adsorption; Alcohols; Aluminum Silicates; Bentonite; Cadmium; Clay; Copper; Electrolytes; Environmental Monitoring; Ethanol; Hydrogen-Ion Concentration; Ions; Kinetics; Metals, Heavy; Methanol; Minerals; Models, Statistical; Soil Pollutants; Solvents; Spectrophotometry; Temperature; Water; Wyoming; Zinc; Zinc Oxide

Temperature, pressure, and time have been thought to control the smectite-to-illite (S-I) reaction, an important diagenetic process used for petroleum exploration. We demonstrated that microorganisms can promote the S-I reaction by dissolving smectite through reduction of structural Fe(III) at room temperature and 1 atmosphere within 14 days. This reaction typically requires conditions of 300 degrees to 350 degrees C, 100 megapascals, and 4 to 5 months in the absence of microbial activity. These results challenge the conventional concept of the S-I reaction and of reaction kinetic models.

Topics: Aluminum Silicates; Clay; Crystallization; Ferric Compounds; Ferrous Compounds; Microscopy, Electron, Scanning; Minerals; Oxidation-Reduction; Pressure; Shewanella; Silicates; Temperature; X-Ray Diffraction

The adsorption and desorption behavior of tributyltin (TBT) from aqueous solution to clay-rich sediments was studied under various conditions (pH, salinity) using the batch technique. Sediments containing illite, kaolinite, and montmorillonite in different proportions were used as sorbent materials. Several physicochemical parameters of the sediments (e.g., Brunauer-Emmett-Teller [BET] surface area, cation exchange capacity [CEC], total organic carbon [TOC]) were evaluated to assess the influence of sediment characteristics to the adsorption capacity for TBT Adsorption isotherms were linear over the concentration range of 100 to 1,000 ng(Sn)/ml. The adsorption coefficient (Kd) values range from 29 to 70 at the pH value generally found in marine systems (pH 8). The adsorption capacity shows a maximum in the range of pH 6 and 7. Salinity is also an important factor in controlling TBT adsorption. The strongest adsorption was observed at salinity of 0/1000, and it strongly decreases with increasing salinity. The adsorption mechanism is controlled by the properties of the clay minerals as well as the aquatic chemistry of TBT. Desorption takes place over the studied pH range (4-8) when contaminated samples interact with TBT-free water at given experimental conditions.

Topics: Adsorption; Aluminum Silicates; Bentonite; Clay; Geologic Sediments; Hydrogen-Ion Concentration; Kaolin; Minerals; Seawater; Trialkyltin Compounds; Water Pollutants, Chemical

The heterogeneous decomposition of CHF2OCH2C2F5, a potential substitute for hydrofluorocarbons, over aluminosilica clay minerals in air, was confirmed to occur at 313 K in a closed-circulation reactor. HC(O)OCH2C2F5, the gaseous main product was produced through hydrolytic elimination of F atoms from the CHF2OCH2- group. CHF2OCH2CF3 also decomposed to HC(O)OCH2CF3 over the clay minerals. The pseudo-first-order rate constants were determined for the decompositions over eight types of clay minerals (19 samples). The various clay minerals had different abilities to decompose these hydrofluoroethers. The decomposition rates per Brunauer-Emmett-Teller surface area and the conversion ratios to HC(O)OCH2C2F5 or HC(O)OCH2CF3 for the reactions over kaolinite, halloysite, and illite were high in comparison to those for the same reactions over montmorillonite, hectorite, and nontronite. The dependence of this heterogeneous reaction on temperature and relative humidity indicates that, in the environment, the reaction could be important only in hot, dry regions. The results did not suggest that sunlight would directly accelerate the decay of CHF2OCH2CF3 or CHF2OCH2C2F5. In the presence of clay-containing soils in arid areas, this hydrolytic oxidation reaction may significantly affect both the lifetime and the degradation products of CHF2OCH2CF3 and CHF2OCH2C2F5 in the troposphere.

Topics: Aluminum Silicates; Clay; Environmental Pollutants; Ethers; Hydrocarbons, Fluorinated; Kaolin; Minerals; Sunlight

In this study, using ion selective electrode techniques, we investigated the influence of pH on metal-ion, Ca2+, Cd2+, and Cu2+, adsorption by Fithian illite. The results showed that Fithian illite exhibited at least two types of metal-ion adsorption sites, high and low strength with the strength of metal-ion-illite surface complexes following the order of Cu2+ > Cd2+ > Ca2+ (strongest to weakest acids) at any of the pH values tested. The ability of metal-ions to form complexes with illite surfaces was affected by type of metal-ions and pH, especially for low metal-ion affinity sites. These sites formed stronger metal-ion complexes at high pH than at low pH, which implicated clay edge sites and indicated that H+ competed with metal-ions for available complexation sites. The data also showed that illite functional groups forming the strongest metal-ion complex did not appear to be pH-sensitive, which implicated wedge siloxane cavities or extremely low pKa clay-edge OH functional groups, but the total number of such sites were very small. The magnitude of the metal-ion-illite stability constants, as metal-ion solution concentration approached zero, on a log-scale, varied from 3.52 to 4.21 for Ca2+, 4.38 to 5.18 for Cd2+, and from 5.23 to 5.83 for Cu2+. These constants were approximately an order of magnitude smaller than those representing illite with sorbed humic fractions. The above results along with the results from our previous studies imply that metal-ion mobility and bioavailability would be affected by soil mineral surface properties, which would be significantly influenced by sorption of humic substances.

Topics: Adsorption; Aluminum Silicates; Cadmium; Calcium; Clay; Copper; Hydrogen-Ion Concentration; Ions; Minerals

Although cyclodextrins are increasingly used in soil decontamination, little is known about their effects on soil physicochemical properties. In this work, the surface and pore properties of randomly methylated beta-cyclodextrin (RAMEB) and three typical clay minerals were characterized, and the effects of RAMEB concentrations on clay minerals were studied using water vapor adsorption-desorption and mercury intrusion porosimetry techniques. As compared to clay minerals, for pure RAMEB very large surface area and volume of nanometer-size pores (micropores) were determined. Energy of interaction with water vapor, volume of micrometer-size pores (mesopores), and fractal dimensions in both pore size ranges of RAMEB were lower than those of the minerals. When increasing amounts of RAMEB were added to the minerals, the surface area and micropore volume decreased and adsorption energy increased. The volume of mesopores decreased after RAMEB treatments for bentonite and kaolin and increased for illite. As deduced from the fractal dimensions increase, the pore structure of the minerals became more complex with RAMEB addition. The observed changes were in general contrary to these expected when RAMEB and minerals coexist as separate, nonreactive phases and suggested strong interaction of RAMEB with clay minerals.

Topics: Adsorption; Algorithms; Aluminum Silicates; Bentonite; Clay; Cyclodextrins; Fractals; Kaolin; Mercury; Minerals; Porosity; Soil; Surface Properties

Pyrolysis experiments were performed on Green River and Monterey Formation kerogens (Types I and II, respectively) with and without calcite, illite, or montmorillonite at 300 degrees C for 2 to 1,000 hours under dry and hydrous conditions. Pyrolysis products were identified and quantified, and a material balance of product and reactants resulted. Significant differences were found in the products generated by pyrolysis of kerogens with and without minerals. Both illite and montmorillonite adsorb a considerable portion (up to 80%) of the generated bitumen. The adsorbed bitumen is almost exclusively composed of polar compounds and asphaltenes that crack to yield low molecular weight compounds and insoluble pyrobitumen during prolonged heating. Montmorillonite shows the most pronounced adsorptive and catalytic effects. With calcite however, the pyrolysis products are similar to those from kerogen heated alone, and bitumen adsorption is negligible. Applying these results to maturation of organic matter in natural environments, we suggest that a given type of organic matter associated with different minerals in source rocks will yield different products. Furthermore, the different adsorption capacities of minerals exert a significant influence on the migration of polar and high molecular weight compounds generated from the breakdown of kerogen. Therefore, the overall accumulated products from carbonate source rocks are mainly heavy oils with some gas, whereas light oils and gases are the main products from source rocks that contain expandable clays with catalytic and adsorptive properties.

Topics: Adsorption; Aluminum Silicates; Bentonite; Calcium Carbonate; Catalysis; Clay; Gases; Geologic Sediments; Hot Temperature; Hydrocarbons; Minerals; Petroleum; Thermodynamics

Low molecular weight organic acids were studied in the course of pyrolysis experiments (200-400 degrees C, 2-1,000 h) of kerogen (Green River Formation and Monterey Formation) with and without the presence of water and minerals (montmorillonite, illite and calcite). C1-C10 aliphatic acids and benzoic acid were identified in the pyrolysis products of kerogen. Their distribution is characterized by a dominance of acetic acid followed by formic and propionic acids with an even/odd preference in the range of C4-C10. Total concentrations of these acids amounted to 0.3% of initial kerogen, indicating that kerogen has a good potential for producing organic acids. Geochemical implications of these organic acids are; (1) they are possible intermediates from kerogen to natural gas (CO2, H2, CH4, C2H6, etc.) by decarboxylation, and (2) they may be important and potential contributors to the generation of secondary porosity by dissolving minerals.

Topics: Aluminum Silicates; Bentonite; Calcium Carbonate; California; Carboxylic Acids; Clay; Fossil Fuels; Geologic Sediments; Hot Temperature; Minerals; Petroleum; Polymers