Montmorillonite Samples Research Articles

Photoformation of Environmentally Persistent Free Radicals During Phototransformation of Poly-Cyclic Aromatic Hydrocarbons (PAHs) on Particles in an Aqueous Solution: The Hydrogenation of PAHs and Effect of Co-Existing Water Matrix Factors.

Environmentally persistent free radicals (EPFRs) generated on particles under irradiation in water have attracted particular attention, and their formation mechanisms are not well understood. This study investigated the photoformation of EPFRs on both actual samples collected from an oil production plant in Panjin, Liaoning, China, and simulated Fe(III)-montmorillonite samples in water. The EPFRs detected on actual samples were not easily generated compared with those in the soil or in the air, based on the concentrations of identified PAHs. EPR signals in the range of 1017 to 1018 spin/g were detected on the simulated Fe(III)-montmorillonite samples. Their g factors were smaller than 2.0030, which indicated the generation of carbon-centered EPFRs. The primary byproducts were identified by chromatography-mass spectrometry (GC-MS), and a possible EPFR formation pathway during PAH degradation was proposed. Hydrogenation of PAHs during the photoformation of EPFRs was observed and might be due to the catalysis of the simulated particles and the interaction of the intermediates. Meanwhile, the effects of the typical anions (NO2- and Cl-) and the surfactant (TWEEN® 80 and sodium dodecyl sulfate) were investigated and indicated that the phototransformation process and adsorption process would affect the formation of EPFRs. Overall, our study provided useful information to understand the photoformation of EPFRs in aqueous environments.

Fundamentals of copper(II) adsorption on phyllosilicate minerals relevant to crud formation in solvent extraction from heap leach liquors

Because of the common presence of different silicate minerals, like kaolinite, montmorillonite and muscovite as gangue minerals in the beneficiation of copper oxide ores, the interaction between copper(II) ions in solution and each of these minerals is a field of strong interest, considering their implications on the aggregation of these minerals in the extreme pH conditions typical of hydrometallurgical unit operations for copper production. After copper adsorption isotherms determination at pH 2 and 4, specific adsorption data were fitted to both Langmuir and Freundlich models. It was found that adsorption is systematically larger at pH 4, and that montmorillonite is the mineral that displays a larger adsorption capacity, as in principle expected by its larger cation exchange capacity, CEC. A good fitting to the Langmuir model was obtained for the three samples, and montmorillonite also appears to conform to Freundlich isotherm predictions, as the tested concentrations of copper(II) do not allow to reach saturation. Furthermore, some desorption is measured for kaolinite and muscovite at the highest copper concentrations, probably because of significant interactions between the adsorbed ions. No such desorption was detected in montmorillonite samples. An XPS analysis of the surfaces of the three minerals suggests that copper adsorption in kaolinite is not associated to a cation exchange process but rather to electrostatic interactions between silica-like faces of the clay. In contrast, ionic exchange of structural calcium (for montmorillonite) or potassium (in the case of muscovite) seems to be the predominant mechanism of Cu(II) adsorption in the other two samples. Electrophoretic mobility determinations agree with this hypothesis: the mobility (always negative, with no traces of charge inversion) decreases in absolute value when kaolinite particles are in contact with solutions of increasing copper concentration at pH 2 or pH 4. On the other hand, the electrophoretic mobility values of muscovite and montmorillonite showed a weak pH and copper concentration dependence, a result that matches well with the ion exchange processes detected in the XPS measurements.

Toxicological Evaluation toward Refined Montmorillonite with Human Colon Associated Cells and Human Skin Associated Cells.

Montmorillonite has been refined to overcome uncertainties originating from different sources, which offers opportunities for addressing various health issues, e.g., cosmetics, wound dressings, and antidiarrheal medicines. Herein, three commercial montmorillonite samples were obtained from different sources and labeled M1, M2, and M3 for Ca-montmorillonite, magnesium-enriched Ca-montmorillonite, and silicon-enriched Na-montmorillonite, respectively. Commercial montmorillonite was refined via ultrasonic scission-differential centrifugation and labeled S, M, or L according to the particle sizes (small, medium, or large, respectively). The size distribution decreased from 2000 nm to 250 nm with increasing centrifugation rates from 3000 rpm to 12,000 rpm. Toxicological evaluations with human colon-associated cells and human skin-associated cells indicated that side effects were correlated with excess dosages and silica sand. These side effects were more obvious with human colon-associated cells. The microscopic interactions between micro/nanosized montmorillonite and human colon-associated cells or human skin-associated cells indicated that those interactions were correlated with the size distributions. The interactions of the M1 series with the human cells were attributed to size effects because montmorillonite with a broad size distribution was stored in the M1 series. The M2 series interactions with human cells did not seem to be correlated with size effects because large montmorillonite particles were retained after refining. The M3 series interactions with human cells were attributed to size effects because small montmorillonite particles were retained after refining. This illustrates that toxicological evaluations with refined montmorillonite must be performed in accordance with clinical medical practices.

Effect of interlayer cations on the adsorption of ionic liquid on montmorillonite clays: comparative study

Industries are the most important resource of water pollution due as a result of toxic pollutants including surfactant or ionic liquids. It becomes urgent to propose low cost and environmentally friendly involving the use of local resources. Here,one of the main ionic liquids (BMImCl) were intercalated into three alkaline-earth, Mg2+, Ca2+, and Ba2+ exchanged montmorillonites. For all samples interlayer spacing after intercalation are similar about 13 Å as measured by X-ray diffraction. These findings are compared with previous results on similar montmorillonite exchanged with every type of alkali cations, i.e. Li+, Na+, K+, Rb+, and Cs+. The basal spacing of intercalated montmorillonite increased as the ionic potential (Z/R) is increased. The FTIR is another tool to confirm the differences between modified and unmodified montmorillonite samples. More specifically, the results showed that the formation of new bands of vibrations (1400–1500 cm-1) and (2850–2900 cm-1).Thermal measurements indicate that homoionic clay display two distinct regions. ‎(I) from room temperature to 160 0C corresponding to physical adsorption and removal of water of hydration, (II) dehydroxylation of the silicate structure in the temperature range of 160-700 0C.

Experimental Study on Permeability and Gas Production Characteristics of Montmorillonite Hydrate Sediments Considering the Effective Stress and Gas Slippage Effect

Summary Gas permeability in hydrate reservoirs is the decisive parameter in determining the gas production efficiency and gas production of hydrate. In the South China Sea (SCS), the gas flow in tight natural gas hydrate (NGH) silty clay reservoirs is significantly affected by the gas slippage effect and the effective stress (ES) of overlying rock. To improve the effectiveness of hydrate exploitation, it is necessary to understand the influence of gas slippage in hydrate reservoirs on the permeability evolution law. For this paper, the gas permeability characteristics and methane production of hydrate montmorillonite sediments were studied at different pore pressures and ESs. Experimental data revealed that the gas permeability of montmorillonite samples before methane hydrate (MH) formation is seriously affected by the Klinkenberg effect. The gas permeability of montmorillonite sediments before hydrate formation is generally smaller than that after hydrate formation, and the gas slippage effect in the sediments after hydrate formation is weaker than that before hydrate formation. With the change in ES, the intrinsic permeability of sediment has a power law relationship with the simple ES. The ES law coefficient n was determined using the response surface method to eliminate the influence of gas slip on gas permeability. As pore pressure decreases and MH decomposes, montmorillonite swelling seriously affects gas permeability. However, the gas slippage effect has a good compensation effect on the permeability of montmorillonite sediments after MH decomposition under low pore pressure. The multistage depressurization-producing process of MH in montmorillonite sediments is mainly 3 MPa depressurization-producing stage and 2 MPa depressurization-producing stage. In this paper, the influence mechanism of gas slippage effect of hydrate reservoir is studied, which is conducive to improving the prediction accuracy of gas content in the process of hydrate exploitation and exploring the best pressure reduction method to increase the gas production of hydrate in the process of exploitation.

Hemolytic Activity and Cytotoxicity of Synthetic Nanoclays with Montmorillonite Structure for Medical Applications.

The factors influencing the appearance of toxicity in samples of synthetic montmorillonite with a systematically changing chemical composition Nax(Al, Mg)2-3Si4O10(OH)2 nH2O, which are potentially important for their use in medicine as drug carriers, targeted drug delivery systems, entero- and hemosorbents have been studied. Samples synthesized under hydrothermal conditions had the morphology of nanolayers self-organized into the nanosponge structures. The effect of the aluminum content, particle sizes, porosity, and ζ-potential of the samples on their toxicity was studied. The cytotoxic effect of the samples on eukaryotic cells Ea. hy 926 was determined using the MTT assay. The hemolytic activity of the samples in the wide concentration range in relation to human erythrocytes was also estimated. It has been established that the toxicity of aluminosilicate nanoparticles can be significantly reduced by correctly selecting their synthesis conditions and chemical composition, which opens up the opportunities for their use in medicine.

Experimental Study on the Evolution of Compressibility and Gas Permeability of Sediments after Hydrate Decomposition under Effective Stress

The effective stress and types of particles significantly affect the permeability of hydrate sediments. In this study, effects of hydrate saturation, hydrate decomposition, effective stress, and particle type on gas permeability and sample deformation of montmorillonite samples and quartz-montmorillonite mixtures were investigated. The results showed that the gas phase permeability increased with hydrate formation. In addition, the decline of sample porosity is the fundamental factor determining the permeability failure rate under effective stress. During methane hydrate decomposition by depressurization, the compression coefficient of samples increases with decreasing pore pressure, which means that decomposing natural gas hydrate makes experimental samples more sensitive to stress. Furthermore, the addition of sand particles significantly affects the compressibility of sediments. In addition, because of the decline of sample porosity and the swelling of montmorillonite, the results of gas permeability show a downward trend when the pore pressure decreases during the decomposition of methane hydrate. Gas permeability of the sample ranges from a few millidarcies to several hundred millidarcies. Furthermore, the content of clay and the particle size in the sample are the key factors in determining the permeability damage rate when the stress increases during decomposition of methane hydrate. Therefore, the addition of quartz sand can reduce damage of gas permeability of sediments caused by effective stress and hydrate decomposition.

Atrazine adsorption and desorption on functionalized montmorillonite: aluminum-pillared and lithium saturated

Atrazine is an herbicide used worldwide, and it is considered a severe environmental contaminant. The present study aims to evaluate the atrazine adsorption in aqueous media in montmorillonite samples which were either in natural state or functionalized through saturation with lithium and pillarization with aluminum by different methods. Montmorillonite saturated with lithium adsorbed significantly more atrazine than the natural montmorillonite sample. Among the samples obtained through the three aluminum-pillarization methods, the mass percentage of adsorbed atrazine was very similar. However, the best combination was the aluminum-pillarization (due to the maintenance of the open interlayer region) and saturation with lithium (due to the significant reduction of the cation exchange capacity of the mineral), because both processes facilitate the interaction of atrazine with the montmorillonite. Another advantage was that the adsorption of atrazine in the pillared and lithium saturated samples had small desorption, which is desirable in the environmental perspective. It is recommended to build filters with aluminum-hydroxy pillared, lithium saturated montmorillonite as an alternative method to rapidly remove atrazine from aqueous media. In addition to the shorter production time, this process resulted in montmorillonite with high occupancy rate and stability of the aluminum-hydroxy pillars.

The Shrink–Swell Process of the Granite Residual Soil with Different Weathering Degree in a Gully System in Southern China

The soil shrink–swell phenomenon produces crack networks and slope instability. However, few studies have involved the continuous shrink–swell process of granite residual soils. The objective of the study is to explore the shrink–swell process of weathered granite soils and its effects on gully development in southern China. The bulk density, soil water content (SWC), shrink–swell ratio (SSR), clay mineral content, and mechanical composition, etc., of soil samples from five soil layers (at depths of 0.3 m, 3.0 m, 7.0 m, 12.0 m, and 16.0 m) along a profile in Yudu County was analyzed. After quantifying the soil properties at different soil depths, we analyzed these data statistically in an effort to identify strong parametric relationships. The results indicated that some properties such as bulk density and shear stress increased with soil depth, while other soil properties, such as plasticity index and liquid limit, were inversely related to depth. Soil cohesion, the angle of internal friction, and shear stress were closely related to the SWC. Every 1% decrease in the SWC resulted in a shear stress reduction of 6.62 kPa. The SSR values exhibited significant variation between the three dry–wet cycles and were closely related to the bulk density values of our kaolin and montmorillonite samples. As an environmental factor, the SWC can trigger changes in internal soil properties such as shear stress and the SSR. Using these data and observations made during our field survey, it can be proposed that continuous shrink–swell variation in deep granite-weathering crust can result in crack formation and gully erosion. It can be inferred that crack development velocity and gully retreat rate may be affected by the soil’s shrink–swell process. Consequently, this information provides insight to understanding the mechanism of gully development in southern China.

Preparation and characterization of sodium polyacrylate grafted montmorillonite nanocomposite for the adsorption of cadmium ions form aqueous solution

High-efficiency adsorbents made from clay minerals have a wide application in remediation of soil and water pollution, especially in the treatment of refractory and highly toxic heavy metals. Montmorillonite itself has a good adsorption capacity and a large modification space for its layered structure. Therefore, carboxylate polymer grafted montmorillonite was developed to improve the adsorption capacity of heavy metals in this paper. Two kinds of modified preparation routes were compared, and a series of batch adsorption tests were conducted to evaluate the influence degree of parameters (contact time, pH, temperature, and cadmium concentration). The structural changes of montmorillonite samples before and after modification were characterized by a series of microscopic analyses and measurement techniques. The results show that the silicon hydroxyl produced by the hydrolysis of silane coupling agent can indeed be grafted by dehydration condensation with Si/Al-OH on clay surface. The grafting chain can be greatly increased by C=C double bond breaking polymerization. The polycarboxylate group can effectively improve the adsorption performance of modified montmorillonite for cadmium ions. The maximum adsorption capacity of modified montmorillonite increased by about 224.75%, reaching 63.49 mg/g. The adsorption model of montmorillonite conforms to Langmuir monolayer adsorption model, while modified montmorillonite samples exhibit Freundlich adsorption model and S-type isothermal adsorption curve characteristics of resin. The preparation method of neutralizing after polymerization of acrylic acid was proposed to be better, which provides technical guidance for scientific and efficient application.

ADSORPTION STUDY OF ACETONE ON THE SORBENTS BASED ON MONTMORILLONITE

Corresponding cation forms of the montmorillonite samples taken from the Ag-Dere bentonite deposit were obtained by processing them with Co2+ and Ni2+ salts. The nature and amount of acid sites formed on the surfaces of the obtained samples were studied by adsorption of acetone using the derivatographic method. The critical diameter of the acetone molecule is d = 5.6A0 and pkα = -7.2. Analysis of derivatograms shows that the mass loss changes depending on the ionic radius, nature and temperature of the cation exchanges as follows: Co2+ mont> Ni2+ mont> natural mont. Based on the conducted study it was estableshed that there are weak, medium and strong electron-acceptor centers on the surface of the sorbent which differ energetically. The endothermic effect observed on the DTA curve at a temperature range of 219.3–566.30C characterizes the physical adsorption of an acetone molecule on the surface of a montmorillonite sample. The effects observed at 706.9 and 775.70C characterize the strong acid sites. The amount of electron-acceptor centers formed on the surface of monmorillonite changes depending on the charge of cation exchangers. The number of electron-acceptor centers formed on the surface of Co2+ bentonite is higher than in other samples. The amount (a.mmol.g) and desorption energy (E, kDc, mol-1) of acetone molecule desorbed from the active sites in different temperature ranges were calculated. It was determined that the most capable of adsorbing acetone molecules is Co2+-montimorillonite, which can be used as a sorbent to prevent envoiremental pollution with acetone. Corresponding cation forms of the montmorillonite samples taken from the Ag-Dere bentonite deposit were prepared by processing with Co2+ and Ni2+ salts. The nature and amount of acid sites formed on the surfaces of the obtained samples were studied by adsorption of acetone using the derivatographic method. Based on the conducted study it was estableshed that there are weak, medium, strong electron-acceptor centers on the surface of the sorbent which differ energetically. The amount (a.mmol.\g) and desorption energy (E, kDc, mol-1) of acetone molecule desorbed from the active sites in different temperature ranges were calculated. As a result of the research, it was found that the most capable of adsorbing acetone molecules is Co2+-form of montimorillonite, which can be used as a sorbent to prevent envoiremental pollution with acetone

Characterization of fine-grained montmorillonite fractions for preparing polymer-clay nanocomposites

Detailed structural characterization of clay minerals contributes to a better understanding of their behavior and physico-chemical properties, making it possible to fully exploit their potential for polymer-clay nanocomposite preparation and their future industrial applications. The object of this study was to characterize fine-grained fractions of four montmorillonite samples and compare them with untreated montmorillonite. The gained results confirmed that fine montmorillonite fractions would be more appropriate precursors for successive preparing of composite materials with sorption property enhancement, useable for environmental remediation.

ДОСЛІДЖЕННЯ СОРБЦІЙНИХ ВЛАСТИВОСТЕЙ ВОЛОКНИСТИХ МАТЕРІАЛІВ, МОДИФІКОВАНИХ ГЛИНИСТИМИ МІНЕРАЛАМИ

Abstract. The paper presents the results of determining the sorption properties of nonwoven materials modified with clay minerals, obtained on the basis of fibrous waste, in relation to the methylene blue indicator to determine the possibility of using the created materials in the purification of light industry wastewater from dyes and heavy metal ions.Purpose. Determination of kinetic regularities of sorption (by methylene blue) of fibrous nonwoven materials modified with different types and amounts of clay adsorbents.Methodology. Nonwovens obtained from elastic fibrous waste of the textile industry were used as a basis in the work. They consisted of Lycra 162 C (PU) complex fibers and Nylon 6.6 f20 / 1 (PA-6.6) fibers in a ratio of 70/30 wt. %. For bonding the nonwoven material, adhesive bicomponent fibers Acebon 4/51 black (4 den) (BVCh) (20 wt%) were added to the initial composition. To enhance the sorption capacity of the PU / PA / BV 80/20 fabric, powders of montmorillonite clay (clay grade PBA-18) and palygorskite (clay grade PP-5) type were introduced in an amount of up to 40% by weight of the nonwoven material. Evaluation of the sorption properties of modified fibrous materials with different clay adsorbents was performed by determining the change in the optical density of MS solutions of a given concentration.Scientific novelty. It was found that fibrous materials modified by the studied samples of montmorillonite and paligorskite clays show high absorption capacity relative to the methylene blue dye due to its multilayer sorption. After 24 hours of processing, the degree of absorption is 70% when using clay brand PBA-18 in the amount of 40% by weight of the fibrous material, which is higher than when using clay brand PP-5 (45%) under the same conditions.Practical value. Sorption materials modified with clay minerals can be further used to treat wastewater from light and chemical industries from heavy metal ions.

Effect of montmorillonite addition (modified and unmodified) on the structural, mechanical, thermal, and morphological properties of nanocomposites based poly (vinyl chloride)

Poly (vinyl chloride)/ montmorillonite nanocomposites were prepared using a melt mixing technique. For this purpose, three montmorillonite samples (MMT) namely, raw montmorillonite (R-MMT), sodium montmorillonite (Na+-MMT) and organically modified montmorillonite (O-MMT) were used with different contents (0, 1, 3, 5, 7 and 9 phr) in the presence of dioctyl phthalate (DOP). X-Ray Diffraction (XRD), Atomic Force Microscopy (AFM), Differential Scanning Calorimetry (DSC), and mechanical testing were used to investigate the physical properties of nanocomposites (PVC/MMT). The results of XRD show that macromolecule chains of PVC may be intercalated or exfoliated into the gallery of modified montmorillonite (Na+-MMT and O-MMT). Microcomposites structure is formed on the PVC/R-MMT nanocomposites when the unmodified montmorillonite (R-MMT) content is added from 1 to 9 phr. However, the glass transition temperature (Tg) of PVC/O-MMT nanocomposites is shifted slightly to lower temperatures. Furthermore, O-MMT plays the role of an internal plasticizer hence increases the distance between macromolecule chains of the polymer. Consequently, the degree of interactions between the chains decreases inducing a decrease in Tg. Synergy effect is also observed on the PVC/O-MMT nanocomposites with the increase in the amount of O-MMT. The morphological study by AFM shows a reduction in surface roughness under the effect of montmorillonite modified, and particularly with (1 phr) of O-MMT.

Amoxicillin Trihydrate Characterization and investigative adsorption using a Brazilian montmorillonite

The objective of this work was to investigate the adsorptive potential of a previously benefited and characterized brazilian montmorillonite sample, regarding amoxicillin trihydrate removal, a zwitterionic species, present in aqueous solutions. 500 mg capsule of antibiotic was properly characterized by XRD, FTIR, SEM/EDS and surface charge measurement through Zeta potential. Amoxicillin aqueous solution and supernatants from adsorption essays were characterized by Molecular Absorption Spectrophotometry in Ultraviolet-Visible Region (UV/VIS), from 200 to 400 nm. Three investigative essays were performed, varying montmorillonite mass (0.050, 0.525 and 1.000 g) and contact time between substances (10, 95 and 180 min). Amoxicillin sample is crystalline, morphologically prismatic, essentially composed of carbon, nitrogen, sulfur, hydrogen and oxygen. Its zwitterionic character was confirmed by Zeta potential, presenting positive (pH 2 to 4), relatively neutral (pH 4 to 6), and negative (above pH 6) surface charges. Test results indicated that the highest removals (21.4 and 41.8 %) were for the largest clay mineral masses (0.525 and 1.000 g, respectively), with pHs close to amoxicillin pka1 (2.68). Larger clay mineral masses have more adsorbent sites, which, associated with components opposite charges in desired pH range, promote a greater interaction. Thus, brazilian montmorillonite can promote amoxicillin removal from aqueous solutions.

Impact of Uniaxial Mechanical Perturbation on Structural Properties and Smectite Porosity Features: Ion Exchanger Efficiency and Adsorption Performance Fate

The use of montmorillonite in the context of engineered barriers makes it possible to minimize the spread of heavy metals from industrial and even radioactive waste. An evaluation of the performance of the mechanisms controlling the clay‐environment interaction and predicting the dynamics/configuration of the interlayer space (IS) is required. This work focuses on a quantitative identification of the structural changes and porosity alteration in the case of heavy metal‐exchanged montmorillonite samples (Co2+ and Cd2+ cations) undergoing mechanical stresses (uniaxial oedometric test (loading/unloading)). Relationships between mechanical stress strength, intrinsic structural response, ion exchanger efficiency, and adsorption performance fate are investigated. This goal is achieved through the correlation of in situ quantitative X‐ray diffraction (XRD) analysis (under an extremely controlled atmosphere reached by varying relative humidity rate %rh) and porosity investigation (assured by combining outcomes from BET (Brunauer–Emmett–Teller) and BJH‐ (Barrett, Joyner, and Halenda‐) PSD (pore size distribution) analysis). Obtained results show an upsurge in the structural heterogeneities accompanying the theoretical increase in the mixed layer structure (MLS) number and developing an unconventional hydration behaviour after stress relaxation regardless of exchangeable cation nature. Experimental XRD patterns are reproduced using MLS, which suggests the coexistence of more than one “crystallite” specie and more than one exchangeable cation indicating a complex cation exchange capacity (CEC) saturation. For extremely low %rh value, a new homogeneous dehydrated state trend is observed in the case of the Co2+ cation. Porosity analysis shows mesopore volume growth for the stressed sample and confirms crystallite exfoliation layer trends, results of the layer cohesion damage, and subsequent constraint strength fluctuations.

Preparation of Triple-Functionalized Montmorillonite Layers Promoting Thermal Stability of Polystyrene.

The objective of this study was to investigate the effect of three different treatments on the morphology, microstructure, and the thermal characteristics of a montmorillonite (Mt) sample, by using hydrochloric acid (HCl), tributyl tetradecyl phosphonium chloride (TTPC) surfactant, and γ-methacryloxypropyltrimethoxysilane (γ-MPS). The resultant nanofillers were characterized by Fourier transform infrared (FTIR), X-ray diffraction (XRD), transmission electron microscopy (TEM), nitrogen adsorption–desorption analysis, X-ray fluorescence spectrometry (XRF), and thermogravimetric analysis (TGA). The results showed that the amount of chemical grafting of the γ-MPS was increased after the acid treatment, whereas the amount of intercalation of the TTPC surfactant was decreased. The preintercalation of TTPC or silylation of γ-MPS, for the Mt sample, had a certain hindrance effect on its subsequent silylation or intercalation treatments. Furthermore, the effect of four different nanofillers on the thermal stability properties of the polystyrene (PS) matrix were also investigated. The results showed an increase in thermal stability for the triple-functionalized Mt, compared with the double-functionalized samples. The onset decomposition temperatures and the maximum mass loss temperatures of the PS nanocomposites were increased by 27 °C and 32 °C, respectively, by the incorporation of triple-modified Mt, as a result of the good exfoliation and dispersion of the nanolayers, more favorable polymer–nanofiller interaction, as well as the formation of a more remarkable tortuous pathway in the continuous matrix.

Spectral Induced Polarization Characterization of Non‐Consolidated Clays for Varying Salinities—An Experimental Study

AbstractClay material characterization is of importance for many geo‐engineering and environmental applications, and geo‐electrical methods are often used to detect them in the subsurface. Spectral induced polarization (SIP) is a geo‐electric method that nonintrusively measures the frequency‐dependent complex electrical conductivity of a material, in the mHz to the kHz range. We present a new SIP data set of four different types of clay (a red montmorillonite sample, a green montmorillonite sample, a kaolinite sample, and an illite sample) at five different salinities (initially de‐ionized water, 10−3, 10−2, 10−1, and 1 mol/L of NaCl). We propose a new laboratory protocol that allows the repeatable characterization of clay samples. The complex conductivity spectra are interpreted with the widely used phenomenological double‐Pelton model. We observe an increase of the real part of the conductivity with salinity for all types of clay, while the imaginary part presents a nonmonotonous behavior. The decrease of polarization over conduction with salinity is interpreted as evidence that conduction increases with salinity faster than polarization. We test the empirical petrophysical relationship between and and validate this approach based on our experimental data and two other datasets from the literature. With this data set we can better understand the frequency‐dependent electrical response of different types of clay. This unique data set of complex conductivity spectra for different types of clay samples is a step forward toward better characterization of clay formations in situ.

Removal of analgesics from aqueous solutions onto montmorillonite KSF

Due to increasing consumption of analgesic drugs associated with their occurrence in wastewater, it is necessary to pay attention to find new accessible types of sorbents for effective drug removal. The objective of this work is the assessment of ability of commercial montmorillonites for the removal of drugs from aqueous solutions since these inexpensive materials exhibit both adsorption and ion exchange properties as well as environmental stability. The commercial montmorillonite KSF, primarily used as acidic catalyst, was used in both unmodified and cetyltrimethylammonium bromide (CTAB) modified form as potential sorbent for three analgesics: paracetamol (PAR), ibuprofen (IBU) and diclofenac (DC) from aqueous solutions. The samples were characterized by X-ray fluorescence (XRFS), X-ray powder diffraction (XRD), simultaneous thermogravimetry and differential thermal analysis (TG/DTA) and high-performance liquid chromatography (HPLC). XRD confirmed the intercalation of CTAB into the montmorillonite structure with the increasing of basal spacing. Thermal analysis also determined the presence of CTAB associated with increasing of the hydrophobicity accompanied by a decrease in dehydration temperature. Also, due to surfactant modification, the temperature of constitution water removal decreased. Adsorption experiments were carried out in a batch mode with different initial concentration of paracetamol, ibuprofen and diclofenac solutions. Montmorillonite samples especially in organically modified form demonstrated sufficient sorption ability of pharmaceuticals from aqueous solutions in the order diclofenac > ibuprofen > paracetamol.

BR13 dye removal using sodium dodecyl sulfate modified montmorillonite: Equilibrium, thermodynamic, kinetic and reusability studies

In this study, Montmorillonite(MMT) samples obtained from Erzurum in Turkey were modified with sodium dodecyl sulfate(SDS) and used for the removal of Basic Red13(BR13) dye. According to equilibrium, kinetic and thermodynamic studies BR13 adsorption was found endothermic, fitted best the pseudo-second-order model and complied with the Langmuir isotherm. The max. adsorption capacity and max. removal yield were calculated as 1111.11 mg/g from the Langmuir model and observed as % 98.24 for BR13, respectively. The best regeneration eluent was found as ethanol and regenerated MMT-SDS can be reused at least three adsorption/desorption cycles. Binary system studies showed that the MMT-SDS was not selective for BR13 adsorption and over 80 % removal observed for BR13, Methyl Orange and Reactive Orange16. A comparative adsorption study between MMT and MMT-SDS showed that although the BET surface area decreased after the modification(46.87 m²/g to 22.47 m²/g) the removal efficiency for MMT-SDS was 68 %, while 45 % for MMT. The modification showed that the target of increasing negative surface charge was reached at −105.25 mV compared to the pre-modification which was -49.62 mV. The intercalation of SDS was observed from the XRD, EDX and FTIR results with a typical reflection of SDS, sulfur presence of 2.83 % and the specific peaks of SDS, respectively.