Search

Well‐Tempered Metadynamics (WT‐MetaD) simulations indicate that composite materials made up of Na‐Montmorillonite (Na‐MMT) coated with ionic liquids (ILs) having hydrophilic cations serve as good adsorbents for a hexameric (1,4) linked β‐D‐glucopyranoside (BGLC). Hydrophilic IL cations are effectively coated on the negative charges lining the Na‐MMT surface while attracting simultaneously the polar oligosaccharides. In this work we have used two less conventional polyethylene glycol (PEG) based IL cations, [mim2 peg1]2+ and [mim2 peg2]2+, paired with [tf2N]− and Cl− anions. Another strongly hydrophilic ion combination, [C2OHmim][Cl], also showed great promise in effective oligosaccharide adsorption on the Na‐MMT surface. The study reveals that the topological polar surface area (TPSA), the octanol‐water partition coefficient (log PO/W), the length of the cationic side chain and the Debye screening length λD ${\left({\lambda }_{D}\right)}$ of the IL are some of the most important factors affecting the adsorption of hydrophilic oligosaccharides on the clay‐IL composites. Among all the systems studied, [mim2 peg2][tf2N]2 having the highest TPSA and a long screening length emerged as the best adsorbent for the oligosaccharide on the IL‐coated clay. [ABSTRACT FROM AUTHOR]

Modified clays with organic molecules have many applications, such as the adsorption of pollutants, catalysts, and drug delivery systems. Different methodologies for intercalating these structures with organic moieties can be found in the literature with many purposes. In this paper, a new methodology of modifying Sodium Montmorillonite clays (Na-Mt) with a faster drying time was investigated by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), BET, and thermogravimetric analysis (TG and DTG). In the modification process, a mixture of ethyl alcohol, DMSO, and Na-Mt were kept under magnetic stirring for one hour. Statistical analysis was applied to evaluate the effects of the amount of DMSO, temperature, and sonication time on the modified clay (DMSO-SMAT) using a 23-factorial design. XRD and FTIR analyses showed the DMSO intercalation into sodium montmorillonite Argel-T (SMAT). An average increase of 0.57 nm for the interplanar distance was found after swelling with DMSO intercalation. BET analysis revealed a decrease in the surface area (from 41.8933 m2/g to 2.1572 m2/g) of Na-Mt when modified with DMSO. The porosity increased from 1.74 (SMAT) to 1.87 nm (DMSO-SMAT) after the application of the methodology. Thermal analysis showed a thermal stability for the DMSO-SMAT material, and this was used to calculate the DMSO-SMAT formula of Na[Al5Mg]Si12O30(OH)6 · 0.54 DMSO. Statistical analysis showed that only the effect of the amount of DMSO was significant for increasing the interlayer space of DMSO-SMAT. In addition, at room temperature, the drying time of the sample using this methodology was 30 min. [ABSTRACT FROM AUTHOR]

Glucosamine–chitosan synthesized by the Maillard reaction was combined with montmorillonite to obtain a nanohybrid composite to immobilize horseradish peroxidase. The material combines the advantageous properties of clay with those of the chitosan derivative; has improved water solubility and reduced molecular weight and viscosity; involves an eco-friendly synthesis; and exhibits ion exchange capacity, good adhesiveness, and a large specific surface area for enzyme adsorption. The physicochemical characteristics of the composite were analyzed by infrared spectroscopy and X-ray diffraction to determine clay–polycation interactions. The electrochemical response of the different polyphenols to glassy carbon electrodes modified with the composite was evaluated by cyclic voltammetry. The sensitivity and detection limit values obtained with the biosensor toward hydroquinone, chlorogenic acid, catechol, and resorcinol are (1.6 ± 0.2) × 102 µA mM−1 and (74 ± 8) nM; (1.2 ± 0.1) × 102 µA mM−1 and (26 ± 3) nM; (16 ± 2) µA mM−1 and (0.74 ± 0.09) μM; and (3.7± 0.3) µA mM−1 and (3.3 ± 0.2) μM, respectively. The biosensor was applied to quantify polyphenols in pennyroyal and lemon verbena extracts. [ABSTRACT FROM AUTHOR]

The inhibition of surface hydration is the most fundamental technical measure for controlling shale borehole stability, but little research has been conducted on the inhibition of surface hydration. In this study, the low-molecular-weight amine inhibitor NH-2 was prepared. The inhibition performance of the NH-2 inhibitor was studied by linear expansion experiment, shale rolling recovery, isothermal adsorption, X-ray diffraction and thermogravimetric analysis. The inhibition mechanism was studied by X-ray diffraction and X-ray photoelectron spectroscopy. The results showed that 1 wt% NH-2 had a lower linear expansion ratio than did 5 wt% KCl and 1 wt% polyamine. The shale rolling recovery rate of the drilling fluid significantly improved after the addition of the NH-2 inhibitor. After the inhibitor NH-2 was added, the unit adsorbed water content of sodium montmorillonite decreased from 0.1104 g/g to 0.0331 g/g. The basal spacing of dry sodium montmorillonite increased from 1.01 nm to 1.3 nm, while that of wet sodium montmorillonite decreased from 1.9 nm to 1.31 nm. The DTG curve has only one low-temperature peak, and the sodium ion content in sodium montmorillonite was greatly reduced. These results showed that the NH-2 inhibitor has good inhibition performance. The inhibitor NH-2 enters the interlayer space of sodium montmorillonite through intercalation, displaces exchangeable cations, and minimizes the base spacing of sodium montmorillonite. Thus, the surface hydration of sodium montmorillonite was completely inhibited. In addition, the decomposition temperature of the NH-2 inhibitor was 232°C, which indicates good thermal stability. This study provides an inhibitor with high temperature resistance and efficient inhibition of hydration. [ABSTRACT FROM AUTHOR]

Herein, firstly, sodium montmorillonite (Na+-MMT) was modified with date seed (DS) powder, and then the anti-corrosion properties of new nanoparticles (DS-MMT) were evaluated on mild steel (MS) in the saline solution phase. Next, DS-MMT was added to epoxy (EP), and their nanocomposite was prepared. Electrochemical impedance spectroscopy (EIS), polarization, and salt spray tests showed that DS-MMT improved corrosion resistance. According to the results of EIS, the coating resistance (Rc) of EP/3 % DS-MMT after 24 days of immersion was 2473 MΩ cm2, while this value was 7.9 MΩ cm2 for EP. Also, the visual observation test showed that after 24 h, the entire surface of the blank sample was filled with rust and corrosion products, but no evidence of corrosion products was observed in the DS-MMT sample. Moreover, the antimicrobial results showed that EP/3 % DS-MMT is inhibitory and killing against Bacillus subtilis and Staphylococcus aureus.

Confinement in microenvironments occurs in many natural systems and technological applications. However, little is known about the behaviour of the immersed nanoparticles. In this work we show that their diffusion, electro-orientation and electric field induced polarization can be determined through electric birefringence experiments. We analyze aqueous dispersions of silver nanowires and clay particles confined inside microdroplets. We have observed that confinement reduces the amount of particles that can be oriented by the external electric field. However, the polarizability of the oriented particles is not affected by the presence of the oil/water boundary, and it is the same as in unbounded media, which agrees with the fact that the electric polarization and related phenomena are short-ranged. [ABSTRACT FROM AUTHOR]

NaMMT clay incorporated and maleic acid (MA) crosslinked polyvinyl alcohol (PVA)‐chitisan (CS) interpenetrating network (IPN) type nanocomposite membranes were prepared for dehydration of acetone by pervaporation (PV). FTIR, XRD, SEM, UV spectroscopy, mechanical properties, contact angle measurement, and DTA‐TGA were used to characterize these membranes. The effect of clay, CS, and MA on the flux and separation factor for water were statistically optimized by Box–Behnken design (BBD). Accordingly, the membrane prepared with 39.3 wt.% CS, 3 wt.% each of MA and NaMMT nanoclay showed a flux/separation factor of 0.176–0.733 kg/m2h/ 277–168 for the pervaporative dehydration of 99 wt.% acetone. Highlights: IPN nanocomposite membranes were prepared from PVA, CS, and nano clay.Structure and properties of the IPNs were characterized.Synthesis parameters were optimized by BBD.Membranes showed high flux and water selectivity for acetone dehydration by PV. [ABSTRACT FROM AUTHOR]

This paper takes Na-montmorillonite adsorption of SO2 molecules as an example to explore the adsorption effect of clay minerals on pollutant gases. Based on the first-principle methods of quantum mechanics, VASP is used to simulate and calculate the adsorption mechanism of Na-montmorillonite on SO2 molecules, finding relationship among adsorption energy, elastic constant and SO2 adsorption amount. The S—O bond length of adsorbed SO2 decreases from 1. 78 to 1. 44 Å after adsorption, O—S—O bond angle of adsorbed SO2 from 119. 50° to 115. 31° while bond length does not obviously change in Na-montmorillonite. In the process of interlayer adsorption, the adsorption energy gradually decreases with the increase of SO2 molecules adsorption. Volume and c-axis direction of the montmorillonite model are linear with the amount of SO2 adsorption. By calculating the montmorillonite elasticity constants under different adsorption capacity, the elasticity constant C33 perpendicular to the crystal face change grootby, decreasing by 142. 27 GPa. In addition, Young's modulus, bulk modulus and shear modulus significantly decrease with the increase of SO2 molecules adsorption. The calculated results will provide theoretical guidance for dealing with gas pollution. [ABSTRACT FROM AUTHOR]

Glucosamine–chitosan synthesized by the Maillard reaction was combined with montmorillonite to obtain a nanohybrid composite to immobilize horseradish peroxidase. The material combines the advantageous properties of clay with those of the chitosan derivative; has improved water solubility and reduced molecular weight and viscosity; involves an eco-friendly synthesis; and exhibits ion exchange capacity, good adhesiveness, and a large specific surface area for enzyme adsorption. The physicochemical characteristics of the composite were analyzed by infrared spectroscopy and X-ray diffraction to determine clay–polycation interactions. The electrochemical response of the different polyphenols to glassy carbon electrodes modified with the composite was evaluated by cyclic voltammetry. The sensitivity and detection limit values obtained with the biosensor toward hydroquinone, chlorogenic acid, catechol, and resorcinol are (1.6 ± 0.2) × 102 µA mM−1 and (74 ± 8) nM; (1.2 ± 0.1) × 102 µA mM−1 and (26 ± 3) nM; (16 ± 2) µA mM−1 and (0.74 ± 0.09) μM; and (3.7± 0.3) µA mM−1 and (3.3 ± 0.2) μM, respectively. The biosensor was applied to quantify polyphenols in pennyroyal and lemon verbena extracts.

Copyright of Journal of Materials Science & Engineering (1673-2812) is the property of Journal of Materials Science & Engineering Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

To understand the occurrence of natural gas hydrates in seabed sediments, it is crucial to examine the mechanisms of methane (CH 4) hydrate formation in sodium montmorillonite (Na-Mt) systems in the presence of amino acid. Accordingly, this study employed kinetics experiments and molecular dynamics simulations to investigate CH 4 hydrate nucleation and growth in an Na-Mt system containing alanine (Ala), leucine (Leu), and phenylalanine (Phe), respectively. Kinetics and Raman experiments showed that, compared with Ala, Leu and Phe enhanced hydrogen bonding between water molecules surrounding Na-Mt. This enhancement was due to the long carbon chain of Leu and the phenyl ring of Phe and facilitated CH 4 hydrate formation. Moreover, in the Na-Mt system, Ala reduced CH 4 consumption, whereas Leu and Phe increased CH 4 consumption. Molecular dynamics simulations revealed that the strength of electrostatic interactions between the negatively charged Na-Mt surface and the functional groups of amino acids affected the distribution of amino acids, thereby altering CH 4 aggregation and CH 4 hydrate nucleation processes. The strong interaction between Na-Mt and Ala significantly disrupted interfacial interactions between Na-Mt and water molecules. In contrast, the weaker interactions between Na-Mt and Leu and Phe, respectively, meant that these amino acids affected CH 4 hydrate nucleation in the bulk-like solution by influencing the arrangement of water molecules. These findings indicate that interfacial interactions between Na-Mt and amino acids play a crucial role in CH 4 hydrate formation. Overall, this study generated insights into the formation kinetics and nucleation properties of CH 4 hydrates in clay mineral–amino acid complexes that may increase understanding about the occurrence of natural gas hydrates in marine sediments. • Kinetics experiments and simulations explored CH 4 hydrate formation in Na-Mt with amino acids. • Electrostatic interactions between Na-Mt surface and amino acids affect CH 4 aggregation and hydrate formation. • Leucine and phenylalanine stay in bulk solution, unlike alanine, which interacts more with the Na-Mt surface. • Leucine's carbon chain and phenylalanine's ring enhance hydrogen bonding among surrounding water molecules. [ABSTRACT FROM AUTHOR]

Abstract Shale gas as green and clean energy is attracting more interest. However, shale hydration and swelling have become the major challenges using water‐based drilling fluids, replacing oil‐based drilling fluids, for developing shale gas. In this work, a low molecular weight branched polyamine (NETS) as clay swelling inhibitor was synthesized. The NETS performed excellent inhibition property by linear expansion experiments and cuttings hot‐rolling recovery. The inhibition mechanism of NETS was investigated using X‐ray diffraction, fourier transform infrared spectroscopy, cation exchange capacity, X‐ray photoelectron spectroscopy, scanning electron microscopy, and zeta potential. The results show that the NETS can adsorb on Na‐Mt, decrease the basal spacing of wet Na‐Mt from 1.91 to 1.43 nm, and replace majority sodium ions from interlayer of Na‐Mt. However, replaceability of sodium ions and inhibition of water molecules of ethylenediamine are worse than NETS. These indicate that the primary amines of NETS had strong interaction with Na‐Mt, tensed clay layers and decrease the basal spacing. The combination of long hydrophobic chain and primary amines makes NETS to adsorb on surface of Na‐Mt, intercalate into interlayer of Na‐Mt with tilted monolayer arrangement, and replace sodium ions. The more the number of primary amine groups, the better the inhibition performance. Therefore, NETS has a great potential to be an outstanding shale inhibitor of water‐based drilling fluids in the future.

Diuron is categorized as a probable human carcinogen by the United States Environmental Protection Agency (EPA). This work is aimed to determine the optimal conditions for the catalytic degradation of Diuron in an aqueous solution with H2O2 using Algerian sodium Montmorillonite (Mont‐Na) as the catalyst. The material is characterized before and after the experiment using X‐ray diffraction, Fourier transform infrared (FTIR) spectroscopy, specific surface area (SBET), elemental analysis, and thermal analysis (TGA/DTA). The surface charge is determined by measuring the point of zero charge. Tests with H2O2 without Mont‐Na provide a 32% conversion rate after 8 h. However, a mixture of 1 g Mont‐Na and H2O2 increases the conversion rate to 91% after 180 min at 25 °C and pH 6.3. The Diuron disappearance is evidenced by high‐performance liquid chromatography using a UV–vis detector (HPLC/UV–vis). Specifically, 3,4‐dichloroaniline (DCA) is the only by‐product. At the basic pH values 9 and 11, a conversion rate of 72.5% is achieved with a lower contact time of 150 min. A change in temperature toward higher values results in a decrease in the degradation rate. Overall, Algerian sodium Montmorillonite is used successfully for the heterogeneous catalytic degradation of Diuron from polluted water. [ABSTRACT FROM AUTHOR]

To improve the quality and increase the shelf life of rainbow trout fillets, nanocomposite clay/low-density polyethylene films were used during 25 days of refrigerated storage (4 °C). Low-density polyethylene (LDPE) films with 5 wt% clay nanoparticles (sodium montmorillonite, MMT) were used for packaging of rainbow trout fillets using 4 different packaging conditions (modified atmosphere packaging (MAP): 60 N2, 35 CO2, and 5% O2; vacuum packaging (VP); air packaging (AP); and control). Fish samples were analyzed on the first day and every 5 days to determine the extent of microbial deterioration, chemical changes, and sensory properties. Based on obtained results, the shelf life of rainbow trout fillets was determined as ~10 days for the control group, and 15, 20, and 25 days for the AP, VP, and MAP packages, respectively. [ABSTRACT FROM AUTHOR]

Magnetically retrievable bismuth tungstate/iron oxide/sodium montmorillonite composite (Bi2WO6/Fe3O4/Na-MMT) was synthesized via a simple solvothermal process. The structure and morphology of as-synthesized composite have been investigated by a series of characterization techniques, the photocatalytic performance was evaluated through the degradation of rhodamine B (RhB) under visible light irradiation, and the possible photodegradation mechanism also has been proposed based on the active species trapping experiments. The results indicated that the Fe3O4/Na-MMT as a magnetic carrier shows excellent adsorption capacity and electron transfer performance, and the h+ radicals could be the main active species in the photocatalytic degradation of RhB. Furthermore, the composite exhibited an extraordinary enhanced photocatalytic activity, much more higher than those of the pure Bi2WO6 and montmorillonite samples, and the composite possesses great paramagnetic properties that contribute a magnetically retrievable performance for solid–liquid separation. [ABSTRACT FROM AUTHOR]

Shale gas as green and clean energy is attracting more interest. However, shale hydration and swelling have become the major challenges using water‐based drilling fluids, replacing oil‐based drilling fluids, for developing shale gas. In this work, a low molecular weight branched polyamine (NETS) as clay swelling inhibitor was synthesized. The NETS performed excellent inhibition property by linear expansion experiments and cuttings hot‐rolling recovery. The inhibition mechanism of NETS was investigated using X‐ray diffraction, fourier transform infrared spectroscopy, cation exchange capacity, X‐ray photoelectron spectroscopy, scanning electron microscopy, and zeta potential. The results show that the NETS can adsorb on Na‐Mt, decrease the basal spacing of wet Na‐Mt from 1.91 to 1.43 nm, and replace majority sodium ions from interlayer of Na‐Mt. However, replaceability of sodium ions and inhibition of water molecules of ethylenediamine are worse than NETS. These indicate that the primary amines of NETS had strong interaction with Na‐Mt, tensed clay layers and decrease the basal spacing. The combination of long hydrophobic chain and primary amines makes NETS to adsorb on surface of Na‐Mt, intercalate into interlayer of Na‐Mt with tilted monolayer arrangement, and replace sodium ions. The more the number of primary amine groups, the better the inhibition performance. Therefore, NETS has a great potential to be an outstanding shale inhibitor of water‐based drilling fluids in the future. [ABSTRACT FROM AUTHOR]

Wan and Zaoui (2024) conducted molecular dynamics simulations (MDS) to explore friction dynamics at the rubber-clay interface under the realm of rubber-soil mixtures (RSM). It's an interesting deviation from the regular RSMs wherein rubber-sand mixtures only have been considered so far. However, it should be noted that the mixing of rubber with clays would result in the creation of heterogeneous mixtures. Furthermore, Wan and Zaoui (2024) have overlooked the effect of moisture, which, in the case of clays, and especially in the case of sodium-montmorillonite, will influence the shearing (which the authors have referred to as sliding) behavior and thus, the friction dynamics. Furthermore, the influence of horizontal stresses and/or confinement, excess pore-water pressure, and interfacial deformation on the RSM have been overlooked, which limit the applicability of the work for the 'dynamic loading conditions'. These issues emphasize the necessity of a broader perspective on the material properties (viz., particle size, specific gravity, etc.) and environmental influences (viz., loading conditions, moisture, etc.) within RSM, and thus, considering these issues might help in enhancing the scientific understanding and future research in this area. [ABSTRACT FROM AUTHOR]

Today, the use of natural biodegradable materials in the production processes is more and more adopted by industry to achieve cyclic economy targets and to improve environmental and human health indexes. Active packaging is the latest trend for food preservation. In this work, nanostructures were prepared by incorporation of thyme oil with natural natrium-montmorillonite and organo-montmorillonite with two different techniques, direct impregnation and the green evaporation–adsorption process. Such nanostructures were mixed with poly-L-lactic-acid for the first time via an extrusion molding process to develop a new packaging film. Comparisons of morphological, mechanical, and other basic properties for food packaging were carried out via XRD, FTIR, TG, SEM/EDS, oxygen and water vapor permeation, and antimicrobial and antioxidant activity for the first time. Results showed that poly-L-lactic-acid could be modified with clays and essential oils to produce improved active packaging films. The final product exhibits food odor prevention characteristics and shelf-life extension capabilities, and it could be used for active packaging. The films based on OrgMt clay seems to be more promising, while the thyme oil addition improves their behavior as active packaging. The PLLA/3%TO@OrgMt and PLLA/5%TO@OrgMt films were qualified between the tested samples as the most promising materials for this purpose.

The current study was conducted to evaluate the ability of mixed adsorbent (Na-MMT + YCW) for the preventing effect of Ochratoxin A in broiler productivity, biochemical parameters, histochemical changes and OTA residues. A total of 96 broiler chicks were grouped in three experimental and one control group (24 chicks in each group, 3 replicates each). Birds were fed basal dietary or that with Ochratoxin A and mixed adsorbent (Na-MMT + YCW) to determine the effect of this compound during mycotoxicoses. When compared with the controls, feed: gain (F/G) were significantly higher for broilers fed diets containing OTA alone (p

In this work, nanoporous sodium montmorillonite clay (Na+–MMT) was successfully modified with 1-methyl-3-(trimethoxysilylpropyl)-imidazolium hydrogen sulfate (Na+–MMT–[pmim]HSO4). This immobilized acidic ionic liquid showed excellent catalytic activity for the synthesis of pyrimido[1,2-a]benzimidazoles and ethyl pyrimido[1,2-a]benzimidazole-3-carboxylates via three-component reactions between aldehydes, 2-aminobenzimidazole and malononitrile or β-dicarbonyl compounds. The procedure gave the products in high yields in very short reaction times at 100°C under solvent-free conditions. Also, this catalyst can be reused for five times without loss of its catalytic activity. [ABSTRACT FROM AUTHOR]

BACKGROUND: Copper is a heavy metal that is widely available in nature and has attracted people's attention because of its toxicity and difficult biodegradability. Using modified montmorillonite to adsorb copper ions (Cu2+) was widely adopted because of its simple operation, high efficiency, and easy availability. RESULTS: Na‐montmorillonite (Na‐Mt) was modified through a Gemini surfactant (containing four ammonium cations) to explore the adsorption capacity for Cu2+ in aqueous media. The resulting product is called G‐Mt. FT‐IR XRDBET results indicated that Gemini surfactant has significantly intercalated into the montmorillonite interlayers. The results ofbatch adsorption experiments presented that the amount of adsorbed (qe) depend on pH value and qe (G‐Mt) can reach to 29.30 mg/g, which was greater than that of Na‐Mt (25.30 mg/g) when pH is 6.0 and initial Cu2+ concentration is 75 mg/L. The experimental data matched well with Langmuir isotherm. The thermodynamic analysis implied that adsorption of Cu2+ was endothermic and a spontaneous process. Molecular dynamics (MD) models were carried out to investigate the microstructure and kinetic information of Gemini cations in the interlayer of G‐Mt. The results elucidated that the distribution and interaction characteristic of ammonium cations of Gemini surfactant including four ammonium cations were completely different from that of the quaternary ammonium salts containing asingle ammonium cation. CONCLUSION: Generally, considering the comprehensive performances, polyamine Gemini surfactant to modify montmorillonite can improve its ability to adsorb Cu2+. The micro environment in the interlayer space and adsorption properties of G‐Mt on Cu2+, which will improve the potential utilization of G‐Mt in soil remediation or wastewater treatment. © 2019 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Innovations in sophisticated optoelectronic devices have increased interest in high-refractive index polymers. Herein, we report innovative nanocomposite films with high linear and nonlinear refractive indices prepared by casting chitosan (Cs) with polyvinyl alcohol (PVA) (50:50 wt%) along with different concentrations (10–50 wt%) of sodium montmorillonite (NaMMT) nanoclay. The refractive indices in addition to other optical parameters of homopolymers and hybrid materials were investigated by UV–Vis. spectroscopy and optical modeling to assess their potential applications in optics. Besides, the structure, morphology, and thermal stability of the prepared films were investigated by a multitude of experimental techniques including X-ray diffraction (XRD), attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), scanning electron microscopy (SEM), atomic force microscopy (AFM), and thermogravimetric analysis (TGA/DTG). The ATR-FTIR, XRD, SEM, and AFM measurements confirmed the complete exfoliation of NaMMT nanolayers in the Cs/PVA matrix. The TGA/DTG revealed an increase in the thermal stability of Cs/PVA film with increasing clay content. The UV–Vis. measurements revealed a decrease in the optical energy gap (E g) and a substantial increase in the linear (n D) and nonlinear (n 2) refractive indices as clay content increased. Additionally, the nanohybrids displayed low UV transmission and reflected about 80 % of UV rays, making them excellent candidates for UV protection. For the first time, the dissipation factor (tan δ) in the UV/Vis. region has been calculated and fitted with the Drude-Lorentz model to predict the plasma frequency (ω p), resonance frequency (ω 0), and electron lifetime (τ) of pristine polymers and nanocomposites. [Display omitted] • Cs/PVA/NaMMT nanocomposite films were prepared by casting method. • Structure analyses revealed complete exfoliation of NaMMT in Cs/PVA matrix. • The thermal stability of Cs/PVA film increased with increasing clay content. • Linear and nonlinear refractive indices enhanced as clay content increased. • Plasma frequency, resonance frequency, and electron lifetime were obtained. [ABSTRACT FROM AUTHOR]

In this study, a novel carboxymethyl cellulose (CMC)-based ternary nanocomposite films containing sodium montmorillonite (Na-MMT) (1, 3 and 5% wt) and titanium dioxide (TiO 2 ) (1, 3 and 5% wt) nanoparticles (NPs) were made via casting method. The results showed that addition of NPs decremented water vapor permeability of the films up to 39% and 50% by adding Na-MMT, and Na-MMT + TiO 2 , respectively, while moisture content, density and glass transition temperature incremented slightly. The nanoclays amplified resistance of the nanocomposites against tensile stress and Young's modulus (YM) of the films at the expense of elongation at break. A synergistic effect of NPs on moisture uptake reduction (≈ 40%) of films was observed. Nano-TiO 2 was strongly effective in UV-light blocking (The films containing 5% TiO 2 removed more than 99% of UV and more than 98% of visible lights). The interactions, crystallinity and morphology of the nanocomposites were investigated by Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD) analysis, and scanning electron microscopy (SEM). Development of hydrogen bonds between the hydroxyl groups of CMC and nanoparticles was indicated by FT-IR spectroscopy. Conforming to the XRD analysis, clay nanolayers organized an intercalated structure in the nanocomposites, whereas a limited agglomeration of TiO 2 nanoparticles led to increment of films crystallinity. SEM micrographs showed well-dispersed Na-MMT and TiO 2 NPs through the films surface especially at low concentrations. In conclusion, although the films loaded with nanoclays exhibited better properties than the control film, inclusion of TiO 2 more improved the functional characteristics of them and extended the potential as a biodegradable packaging. [ABSTRACT FROM AUTHOR]

This study reports the effect of three new organic cations including hexadecylamine (HDA), tetradecylamine (TDA) and 1-(4-aminophenyl)-3-(4-chlorophenyl)prop-2-en-1-one, chalcone (CH) on the basal spacing of the montmorillonite clay to MMT modification. Fourier Transform infrared spectroscopy (FTIR) was used to evaluate the incorporation of these cations in the MMT. X-ray diffraction technique was utilized to indicate the basal spacing of the treated clay as a measure of susceptibility of new organoclays. The FTIR and XRD results shown that the three new organic cations were successfully incorporated in the montmorillonite clay. [ABSTRACT FROM AUTHOR]

In this paper, we present a facile approach for the synthesis of polysaccharide-based carbon aerogel by sol-gel processing, freeze-drying, and pyrolysis of a sodium carboxymethyl cellulose/sodium montmorillonite composite aerogel. The as-prepared carbon aerogel was characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray diffractometry, nitrogen adsorption measurements, and vibrating sample magnetometry. The carbon aerogel obtained in this study possessed low density (0.064 ± 0.0029 g/cm3), a high surface area (185 m2/g), and flame retardance. Measurements of the magnetic properties indicated that the carbon aerogel exhibited typical ferromagnetic characteristic at room temperature. The absorption capacity of the carbon aerogel for oils and organic solvents is as much as 10-20 times its own weight. Moreover, a method of combustion could be employed to recycle the carbon aerogel. The results imply that the carbon aerogel is a potential cost-effective adsorbent for oil and organic pollutants from aqueous solutions in environmental pollution cleanup. [ABSTRACT FROM AUTHOR]

Inhibiting the surface hydration of clay is the main task for the water-based drilling fluids used in the development of shale gas. Branching polyethyleneimine (BPEI) completely inhibits the clay surface hydration. However, the use of BPEI is limited by its high toxicity. In this paper, BPEI was modified by grafting with hydroxyethyl groups to reduce the toxicities of BPEI hydration inhibitors. The structures and properties of the modified BPEI were characterized by infrared spectroscopy, mass spectrometry, the luminescent bacteria method, isothermal adsorption, X-ray diffraction, thermogravimetric analysis, contact angle measurement, scanning electron microscopy, X-ray photoelectron spectroscopy and molecular simulations. The relative luminescence rate of the modified BPEI inhibitors increased from 14 % to 62 % with increases in the number of grafted hydroxyethyl groups. After hydrated sodium montmorillonite (Na–Mt) contacted the modified BPEI inhibitors, the basal spacings of the Na–Mt decreased from 1.90 nm to a minimum of 1.40 nm, and the DTG curve had only one low-temperature peak. Molecular simulations showed that the energy for adsorption of the inhibitor on the Mt surface increased with increases in the number of grafted hydroxyethyl groups. These results suggested a structure-activity relationship for inhibition and the biological toxicity of the modified BPEI inhibitor. That is, within the range of 20:1 to 5:1 for the molar ratios of amino and hydroxyl groups, increases in the number of grafted hydroxyethyl groups gradually decreased the biological toxicities of BPEI inhibitors, and the inhibition performance was gradually enhanced. BPEI-OH4 (amino:hydroxyl = 5:1) showed the best performance among the modified BPEI inhibitors. This provides an excellent inhibitor and a low-toxicity modification method, which will facilitate the development of environmentally friendly high-performance water-based drilling fluids. • The biotoxicity of BPEI was effectively reduced by grafting of hydroxyethyl groups. • The inhibition efficiency of BPEI was improved by grafting of the hydroxyethyl groups. • The adsorption capacity of BPEI was improved by grafting with different numbers of hydroxyethyl groups. • These results provide a way to decrease the toxicities of amino inhibitors without weakening the inhibition performance. [ABSTRACT FROM AUTHOR]

A novel monomeric amine sodium montmorillonite swelling inhibitor: N1,N2-ditetradecy-N1, N1, N2, N2-tetrakis (2-hydroxyethyl) ethane-1,2-diaminium bromide was obtained from diethanolamine, 1-bromotetradecane, and 1, 2-dibromoethane. N1,N2-ditetradecy-N1, N1, N2, N2-tetrakis (2-hydroxyethyl) ethane-1,2-diaminium bromide was characterized by means of Fourier transform infrared, 1H NMR spectroscopy, elemental analysis, linear swelling tests, particle size distribution tests, X-ray diffraction, and thermogravimetric. Linear swelling tests showed that the swelling height of sodium montmorillonite in 1.0 wt% N1,N2-ditetradecy-N1, N1, N2, N2-tetrakis (2-hydroxyethyl) ethane-1,2-diaminium bromide solution was only 2.0 mm after 16 h (fresh water was 5.0 mm). Particle size distribution tests exhibited that the median diameter and mean particle size of sodium montmorillonite in 1.0 wt% N1,N2-ditetradecy-N1, N1, N2, N2-tetrakis (2-hydroxyethyl) ethane-1,2-diaminium bromide solution obviously increased to 16.1 and 85.4 µm, respectively (fresh water was 8.1 and 21.8 µm). In thermogravimetric tests, in comparison with pure sodium montmorillonite, the decrease of water content in sodium montmorillonite/N1,N2-ditetradecy-N1, N1, N2, N2-tetrakis (2-hydroxyethyl) ethane-1,2-diaminium bromide indicated N1,N2-ditetradecy-N1, N1, N2, N2-tetrakis (2-hydroxyethyl) ethane-1,2-diaminium bromide expelled the water molecules out of the interlayer, which was beneficial to wellbore stability. Fourier transform infrared spectra of certain concentration N1,N2-ditetradecy-N1, N1, N2, N2-tetrakis (2-hydroxyethyl) ethane-1,2-diaminium bromide/sodium montmorillonite indicated the successful physical adsorption and interaction between N1,N2-ditetradecy-N1, N1, N2, N2-tetrakis (2-hydroxyethyl) ethane-1,2-diaminium bromide with sodium montmorillonite. In addition, the results of X-ray diffraction tests showed the obtained 1.0 wt% N1,N2-ditetradecy-N1, N1, N2, N2-tetrakis (2-hydroxyethyl) ethane-1,2-diaminium bromide solution could remarkably reduce the interlayer distance of wet sodium montmorillonite (from 1.94 to 1.37 nm). [ABSTRACT FROM AUTHOR]

This work deals with the Layer by Layer (LbL) assembly of hybrid organic/inorganic flame retardant coatings made of Octa-ammonium POSS (polyhedral oligomeric silsesquioxane) and sodium montmorillonite clay on polyester (PET) fabrics. The effects of ionic strength on the achieved flame retardancy properties were investigated. The coating growth as a function of different ionic strengths was evaluated by infrared spectroscopy. 0.10 M NaCl was found able to promote the highest adsorption of each coating species at each deposition step strongly affecting clay stacking as evaluated by X-ray diffraction measurements. The coatings on PET assembled at high ionic strength turned out to be more homogeneous and thicker than the reference one. Thanks to the increased thickness and better surface coverage, the same coatings efficiently suppressed the melt dripping phenomenon and significantly slowed down flame spread rate in horizontal flammability tests with only 2 wt% of coating mass added. Furthermore, the same performances were maintained after 1 h washing at 70 °C. By cone calorimetry, coated fabrics showed a strong reduction in the combustion kinetics by nearly halving the peak of heat release rate. This paper provides an important insight on the viability of tuning deposition of LbL coatings on fabrics employing industrial-like processes by simple modification of ionic strength. [ABSTRACT FROM AUTHOR]

This work presents a novel way to produce a thermally stable nanoclay with an increased interlayer space, which are the essential requirements in fabricating clay-polymer nanocomposites. Sodium montmorillonite (Na-Mt) was functionalized through two separate, consecutive reaction systems. Functionalization with an aminosilane was first performed, in order to produce reactive groups at the silicate nanolayers. In the second step, amino acid monomers were employed for a further reaction with silane-modified nanoclay. X-ray diffraction results demonstrated an increased d 001 -value (24 Å) using 10 mmol γ-aminobutyric acid. The 001 reflection peak disappeared when 5 mmol ω-aminoundecanoic acid/g Mt was used as the second type of amino acid. Transmission electron microscopy images of modified Mt with 10 mmol ω-aminoundecanoic acid exhibited a well separated or exfoliated structure of nanolayers. Thermogravimetric measurements indicated a trend of increasing thermal stability of the modified nanoclays (350 °C to 400 °C) with increasing amounts of initial ω-aminoundecanoic acid. Based on these results, optimizing the modifiers and synthesis conditions can control the properties of modified nanoclay. Tensile modulus and strain at break of HDPE/2 mass% modified Mt showed 10% and 14% enhancements, respectively, due to the increased d 001 -value of the nanofiller, which results in greater filler-polymer interaction. [ABSTRACT FROM AUTHOR]

In the duration of initial flocculation stage, required time for waiting prior to the gravitational collapse of Na montmorillonite suspension in the semi-dilute coagulated regime (with solid volume fraction of 1.097 × 10) was analyzed as a function of ionic strength for the two different pH values (pH = 4.0 (acid) and pH = 9.5(alkaline)). The obtained result clearly demonstrated that the duration time correlates the coagulation rate of clay particles. That is, the duration time is shorter (but not to be zero) for the system undergoing rapid coagulation which takes place under sufficiently high ionic strength. In this region, the effect of pH is shielded by the complete compression of electric double layer. However, the duration becomes longer with a decrease of ionic strength in accordance with the decrease of the rate of coagulation. In addition, under the condition approaching to the region near critical coagulation concentration, further longer duration is observed for the case of high pH value as compared to that obtained for the case of lower pH value. The reason for the additional increase of duration was ascribed to the elimination of positive charge along the edge of clay sheet under alkaline condition. In the case of low pH, on the contrary, the effect of the oppositely charged edge(+)-to-face(−) interaction is considered to induce attraction between clay particles which contributes to induce heterocoagulation. This effect will result in the shorter duration time for the case of low pH than that of high pH. [ABSTRACT FROM AUTHOR]

The current study was conducted to evaluate the ability of mixed adsorbent (Na-MMT+YCW) for the preventing effect of Ochratoxin A in broiler productivity, biochemical parameters, histochemical changes and OTA residues. A total of 96 broiler chicks were grouped in three experimental and one control group (24 chicks in each group, 3 replicates each). Birds were fed basal dietary or that with Ochratoxin A and mixed adsorbent (Na-MMT+YCW) to determine the effect of this compound during mycotoxicoses. When compared with the controls, feed: gain (F/G) were significantly higher for broilers fed diets containing OTA alone (p<.05). No differences were found between the F/G of broiler chickens fed diets without OTA and those of chickens fed mixed adsorbent. The diet containing 2mg OTA/kg without adsorbents added increased relative liver, kidney, spleen weights and decreased relative thymus, bursa weights. Alterations in the levels of serum TP, ALB, GLB, BUN and enzymatic activity of ALT, AST, ALP and GGT were observed for OTA diets, and moderate protection was provided by the sorbent. Supplementing mixed adsorbent group (Na-MMT+YCW) showed intestinal villus height and crypt depth similar to control chicks, and a significant reduction residue in livers and kidney tissue, as well as a significantly higher OTA content in the faeces compared with OTA- group were recorded. These results suggest that effects of OTA treatment were ameliorated when mixed adsorbent was used in the broiler chick diets. [ABSTRACT FROM AUTHOR]

Biodegradable polymers, such as polybutylene succinate (PBS), have attracted a lot of attention in the scientific community recently due to a rapid growth of intensive interest in the global environment for alternatives to petroleum-based polymeric materials. Chalcone (CH), hexadecylamine (HDA), and tetradecylamine (TDA) were used as one of organic compounds to modify natural clay (sodium montmorillonite). The clay modification was carried out by stirring the clay particles in an aqueous solution of CH-MMT, HDA-MMT and TDA-MMT increases from 1.27 to 1.51, 1.57 and 1.78 nm, respectively. The modified clay was then used in the preparation of the PBS/epoxidized palm oil (EPO) blend nanocomposites. They were prepared by incorporating 0.5-5% of CH-MMT, HDA-MMT and TDA-MMT. The interaction of the modifier in the clay layer was characterized by X-ray diffraction (XRD) and Fourier transform infrared (FTIR). The nanocomposites were synthesized by solution casting of the modified clay and a PBS/EPO blend at the weight ratio of 80/20, which has the highest increase in the tensile strength of the blend. The XRD, scanning electron microscopy and transmission electron microscopy results confirmed the production of nanocomposites. PBS/EPO modified clay nanocomposites show higher thermal stability and significant improvement of comparison with those of the PBS/EPO blend. [ABSTRACT FROM AUTHOR]

Smart nanogel capsules are attracting great attention to act as self-healing materials for polymers and epoxy coating and as anticorrosion materials. The present work aimed at incorporating nanogel among silicate layers of sodium montmorillonite (Na-MMT) to increase its dispersibility into an epoxy matrix so as to be used as self-healing nanocomposites. For this purpose, N-isopropyl acrylamide (NIPAm) as a salt-sensitive monomer was selected to prepare smart nanogels to disperse the Na-MMT layers. The chemical structure, surface morphology, particle size distribution, surface charge, and degree of exfoliation of Na-MMT with NIPAm nanogel were investigated. The ability of Na-MMT/NIPAm to modify the mechanical, surface, and self-healing characteristics of epoxy matrix was studied. The corrosion inhibition and self-healing mechanism were discussed in light of salt spray resistance of epoxy nanocomposites to protect steel from corrosive environments. [ABSTRACT FROM AUTHOR]

Two types of nanoclay filled dry rubber compounds were prepared by incorporating sodium montmorillonite (MMT) into natural rubber (NR) at latex stage. Nanoclay filled rubber sheets prepared by acid co-coagulation (ACC) and acid free co-coagulation (AFCC) rubber production methods were milled and compounded to develop nanoclay filled dry rubber compounds. The MMT loading was varied from 0 to 20 phr. Both the above methods are not used as filler incorporation methods in dry rubber industry. AFCC rubber vulcanisates, compared to ACC rubber vulcanisates showed improved mechanical properties mainly due to increased crosslink density associated with the presence of natural accelerators and nano-scale dispersion obtained under acid free environment. The AFCC method is proposed as a new route in filler incorporation, which shows the best mechanical properties at a MMT loading of 8 phr. At higher MMT loadings, due to the formation of aggregated clay structures associated with filler-filler interactions, tensile strength and elongation at break decreased. Modulus and hardness increased with the increase of MMT loading, while tear strength remained unchanged. XDR deffractograms and SEM images revealed that the AFCC rubber at optimum loading has partially exfoliated clay structures with fine phase morphology. DSC analysis revealed that no significant rubber-filler interactions are formed in the rubber vulcanisates. [ABSTRACT FROM AUTHOR]

The objective of this work was to manufacture biodegradable films based on cassava starch, polyvinyl alcohol (PVA) and sodium montmorillonite (Na-MMT), using glycerol as a plasticizer. These films were characterized according to their microstructure, optical, mechanical, and barrier properties. The combination of starch-PVA-MMT resulted in films with a more homogeneous surface than starch films. The introduction of PVA into the starch matrix led to the formation of films with lower water vapor permeability (WVP), higher tensile strength and greater elongation. MMT was exfoliated in the films, resulting in greater stability for different relative humidities, lower WVP, higher resistance and lower flexibility.

In this study, feather keratin/polyvinyl alcohol/tris(hydroxymethyl)aminomethane (FK/PVA/Tris) bionanocomposite films containing two types of nanoparticles, namely one-dimensional sodium montmorillonite (MMT) clay platelets (0.5, 1, 3, and 5 wt%) and three-dimensional TiO2 nanospheres (0.5, 1, 3, and 5 wt%), are prepared using solvent casting method. X-ray diffraction studies confirm the completely exfoliated structure of FK/PVA/Tris/MMT nanocomposites. The successful formation of new hydrogen bonds between the hydroxyl groups of the film matrix and the nanofillers is confirmed by Fourier transform infrared spectroscopy. The tensile strength, elongation at break, and initial degradation temperature of the films are enhanced after MMT and TiO2 incorporation. The water vapor permeability, oxygen permeability, and light transmittance decrease with increase in TiO2 and MMT contents. In summary, nanoblending is an effective method to promote the application of FK/PVA/Tris blend films in the packaging field.

Montmorillonite (Mt) as a solid acid catalyst or support has been widely used in catalytic reactions. However, the existence and catalytic activities of its surface basic sites have rarely been revealed. Here, the surface and structure of Na-Mt are modulated by thermal treatment, providing both acidic and basic sites for the transesterification of glycerol with dimethyl carbonate (DMC) to glycerol carbonate (GLC). The experimental results showed that the thermally activated Na-Mt exhibited bifunctional catalytic properties in glycerol transesterification. The Na-Mt calcined at 400 °C had a basic site density of 1.38 mmol/g and led to a glycerol conversion of 96.8% and a GLC yield of 94.5%. Edge surfaces of Na-Mt provided MII (MIII) atoms as Lewis acidic sites for facilitating the generation of glyceroxide anions from activated glycerol and -M-OH groups as Brønsted and Lewis basic sites for enhancing the carbonyl activation of DMC. This work revealed the co-existence of acidic and basic sites over thermally activated Na-Mt for synergetic catalysis in the transesterification of glycerol to GLC, making the development of Mt-based materials as bifunctional catalysts for one-pot acid-base catalytic processes possible. • Coexisting acid and basic sites on sodium montmorillonite (Na-Mt) is revealed. • Reactive sites on edge surfaces of Na-Mt is altered with calcination temperature. • Synergetic effect of acid and basic sites results in high catalytic activity of Na-Mt. • Understanding on the structure-activity relationship of Na-Mt as bifunctional catalyst. • Bring insight into the surface and interface properties of Na-Mt. [ABSTRACT FROM AUTHOR]

Ionic liquids have attracted significant research interest due to their unique thermal stability. In this paper, the influence of a water-soluble ionic liquid on the rheological and filtration properties of water-based drilling fluids at high temperature is investigated. The drilling fluids are evaluated by means of rheological and filtration tests following the American Petroleum Institute (API) standards, submitted to an aging process or at high temperature. The experimental results show that the rheological behavior of water-based drilling fluids is improved and enhanced in the presence of low concentration of ionic liquid (as low as 0.05 mass%) at high temperatures (even up to 240 °C). Meanwhile, the high-temperature and high-pressure (HTHP) filtration volumes are reduced by as much as 52% compared with that of polymer water-based drilling fluids without ionic liquid. The study of the mechanism demonstrates that the water-soluble ionic liquid have an excellent capacity to improve the rheological and filtration properties of water-based drilling fluids at high temperatures due to the high thermal stability and cation exchange ability of the ILA. [ABSTRACT FROM AUTHOR]