Exploring reliable hydrogenation catalysts to remove trace olefins in aromatic hydrocarbons through hydrogenation is an important topic. In this paper, a bimetallic Cu–Ru/montmorillonite (Cu–Ru/M) catalyst was prepared using a step-by-step impregnation method, and the effects of bimetallic catalysts on removing olefins were assessed. The catalysts were characterized using X-ray diffraction, Brunauer–Emmett–Teller specific surface area, inductively coupled plasma atomic emission spectrometry, high-resolution transmission electron microscopy and temperature-programmed reduction of H2. The results show that there is a strong interaction between Cu and Ru on the Cu–Ru/M catalyst, which improves the dispersion of the metals on the surface of the support M. The hydrogen spillover phenomenon of Cu–Ru/M enhances its activity and adsorption capacity for hydrogen species. The catalytic performance test confirmed that the bimetallic catalyst has significantly greater activity and stability. The optimal loadings are 5% copper and 1% ruthenium, and the performance of this catalyst is comparable to those of noble-metal Pt/M catalysts.

This paper reports a novel approach in the study of trace-element mobility during the argillization of volcanic glass that is based on in situ laser ablation inductively coupled plasma mass spectrometry glass analyses and that of spatially related illite-smectite collected in the form of fraction separates. The material studied originates from lacustrine sediments of the Dinaride Lake System that bear evidence of intensive weathering of distal tephra during the Miocene climatic optimum. Yttrium and HREE were probably mobilized from decomposing glass in the form of carbonate complexes and were consequently depleted significantly in the clays studied. On the other hand, the Mg-rich illite-smectite demonstrates an elevated adsorption potential of solvated LREE complexes. This may be explained through clay surface geochemistry controlled largely by Mg for Al octahedral substitution. This paper highlights the role of eogenetic 2:1 clay aluminosilicates that, under favourable geological conditions, may be conducive to secondary REE enrichment and the formation of potential ion adsorption-type deposits.

Clays from the Saïss basin (northern Morocco) used traditionally in the ceramic industry in the Fez area were studied using mineralogical and physicochemical techniques to evaluate their potential suitability as raw materials for ceramics manufacture. X-ray diffraction was used to determine their mineralogical composition. The physical properties determined were particle-size distribution and consistency limits. The chemical composition was determined using X-ray fluorescence analysis and Fourier-transform infrared spectrometry. The structural changes of the mineral phases in the raw materials during firing were studied over a temperature range of 500–1000°C. In the pottery site from Fez, generally potters use a mixture of 25% fine clay (ARFS) from the upper part of the Miocene marls and 75% sandy clay (ARFR) from the lower part of the Miocene marls. The ARFS clay yielded very rigid specimens after firing that artisan potters would find difficult to handle so as to produce desired shapes and sizes. However, the specimens obtained from ARFR clay show signs of faltering. The mixture of these two clayey materials from this pottery site is therefore necessary to obtain the optimal paste for ceramics purposes. The chemical compositions indicated that SiO2, Al2O3, CaO and Fe2O3 are the major minerals, with trace amounts of K2O and MgO. Quartz, feldspars and clay minerals prevail in all samples. Kaolinite, illite and smectite are the dominant clay mineral phases, with traces of chlorite and interstratified illite–smectite. The classification of these samples using appropriate ternary diagrams showed that the proportions used in the mixture produce a new material with adequate characteristics for the production of traditional ceramics.

Clay minerals are used widely in health products both as cosmetic and pharmaceutical ingredients. To optimize use, natural compounds are mixed with clay powder. The aim of the present study was to synthesize new, coloured hybrids based on purified Tunisian clay and powders of natural flowers: Malva sylvestris, Chrysanthemum coronarium, Silene dioica, Anagallis monellin and Pelargonium × hortorum. The floral pigments in Tunisian flowers were studied. The chlorophylls (a and b), total flavonoids (TF), total phenolic compounds (TPC), and carotenoids were analyzed using UV-Vis spectrophotometry and high-performance liquid chromatography (HPLC-DAD). In addition, the antioxidant capacity was determined using the oxygenated radical absorption capacity assay (ORAC) and the antioxidant capacity to reduce ferric ion assay (FRAP). The properties of the studied clay were evaluated by means of pharmaceutical and microbiological tests. The coloured hybrids were prepared by solid–solid reaction and analyzed using X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy. Chlorophyll a is present in large quantities in the Malva flower which presents the smallest antioxidant capacity. Chlorophyll b and the TPC are more abundant in the Pelargonium × hortorum. The TF appears in large quantities in the Anagallis flower. The carotenoids are present in the largest amounts in the Chrysanthemum. The results of the clay characterization justify its use as a pharmaceutical and cosmetic agent. The mixture of dried flowers and purified clay is used in the synthesis of new and biocoloured hybrids; these can be used as biocosmetic products without negative side effects on human health or the environment.

Samples from the pyrophyllite reserves in the Malatya–Pütürge region, used in the production of the whitest cement in Europe, were beneficiated using flotation. The mineralogical composition of the natural pyrophyllite, as determined using X-ray diffraction, includes pyrophyllite, kaolinite, quartz, illite–mica and feldspar. The chemical composition of pyrophyllite contains 69.75% SiO2 and 23.04% Al2O3. The pyrophyllite percentage (40–45 wt.%) of the natural sample increased to 60–80 wt.% after flotation. In flotation experiments, the effects of reagent amounts, types and their mixtures were investigated. Methyl isobutyl carbinol (MIBC) and pine oil as frothers and kerosene as a collector were used in the flotation studies. The use of reagents as mixtures has a positive effect on the beneficiation compared to use on their own. The best result was obtained for a mixture of MIBC with kerosene, which is a non-ionic hydrocarbon oil, yielding a concentrate containing 26.63% Al2O3. Improved results were also observed for kerosene plus frother mixtures after flotation cleaning circuits. The bubbles formed during flotation were photographed and the bubble diameters were measured using the ImageJ program. The Al2O3 content was evaluated by correlating the bubble diameters. In general, selectivity decreased during experiments in which bubble diameters were reduced.

Two novel modified montmorillonite (Mnt) components were prepared using Mnt nanoparticles and two surfactants: docosyl-trimethylammonium chloride (BTAC) and sodium dodecyl sulfate (SDS). These modified Mnts were used to remove a carcinogenic and harmful dye, crystal violet (CV), from solution. Optimization and modelling studies of the adsorption of these two modified Mnts were performed using response surface methodology. Four influential variables (concentration of adsorbent, temperature, pH and CV concentration) were studied to obtain the optimum conditions for CV removal. The optimal values of these variables for the two modified Mnts yielded 100% dye-removal efficiency. The optimum conditions for CV adsorption on Mnt-BTAC and Mnt-BTAC-SDS, respectively, are temperatures of 25.00 and 33.29°C, pH values of 9 and 10.1, CV concentrations of 50.00 and 10.44 mg L–1 and adsorbent concentrations of 1.00 and 0.98 g L–1. In equilibrium studies of the two modified Mnts, the Temkin isotherm was selected as an appropriate model, and in kinetic studies of these Mnts, the fractal-like integrated kinetics Langmuir model was found to be the best model. The Mnt-BTAC-SDS component is an affordable adsorbent with high adsorption capacity for CV.

The worldwide use of pharmaceuticals is of concern to those researchers who develop new techniques for the removal of these compounds from the aquatic medium. The objective of the present work was to characterize and evaluate the performance of a commercial, bentonite-based organophilic clay in removing ivermectin from aqueous solution. The adsorbent was characterized by nitrogen physisorption, thermogravimetric-differential scanning calorimetry (TG-DSC), X-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FTIR). Batch-scale adsorption experiments were performed to evaluate the kinetics, isotherms, thermodynamics and effect of pH on removal of this drug and reuse of the clay. The bentonite has a small specific surface area with an irregular surface. The Elovich kinetic model fits the experimental data better than other models, indicating that chemisorption contributes to drug removal in this case. The Langmuir and Sips isothermal models best fit the experimental equilibrium data. The process was shown to be favorable (ΔG°ads<0), endothermic (ΔH°ads>0), with an increase in the degrees of freedom at the solid–liquid interface (ΔS°ads>0), and with characteristics of a physical-chemical adsorption process (Ea = 11.065 kJ mol–1) under the study conditions. Adsorption was favored at the natural pH of the solution and the organophilic clay could be regenerated with water and reused in consecutive adsorption cycles. The amount of ivermectin adsorbed on the organophilic clay ranged from 1.78 to 3.88 mg g–1. The organophilic clay was shown to be a cost-effective potential adsorbent for ivermectin-contaminated water-treatment applications.

High-performance mullite-based composite ceramics were prepared successfully using natural kaolin and alumina as raw materials and ZrO2 as an additive. The influence of sintering temperature and ZrO2 content on the sintering behaviour and mechanical properties of zirconia-toughened mullite ceramics was studied systematically. With increasing sintering temperature from 1450°C to 1560°C, the primary phases of as-sintered composite ceramics were mullite and corundum with a small amount of ZrO2, and the bulk density of the composite ceramics increased from 2.29 to 2.72 g cm–3. Furthermore, the ZrO2 phase transition promoted transgranular fracture, and ZrO2 grains were pinned at the grain boundaries, thereby enhancing the mechanical strength of the composite ceramics. Moreover, the AZS12 sample, with 12 wt.% ZrO2 and sintered at 1560°C, had the greatest flexural strength and fracture toughness of 91.6 MPa and 2.47 MPa m–1/2, respectively. Adding ZrO2 to the composite ceramics increased their flexural strength by ~37.6%.

Artificially coloured smectites (smectite pigments) were prepared via the sorption of anionic dyes on smectite saturated with ferric ions (Fe-smectite). Fe-smectite has a surface charge and is capable of decolourizing aqueous solutions containing single-component anionic dyes (Amaranth, Brilliant blue FCF and Tartrazine) or multi-component dyes (dye mixtures). Kinetic and equilibrium models were used to describe the sorption of individual dyes, whereas the decolourization of the multi-component system was studied by monitoring the reduction in the intensity of the absorption bands in the visible light region. The Langmuir–Freundlich dual-site model presented the best fit to the experimental data, and the sorption kinetics followed the pseudo-second order model. The smectite pigments were dispersed in colourless paint (10%, w/w), acting as organic–inorganic hybrid pigments. Colorimetric measurements of the powdered smectite pigments dispersed in colourless real-estate paint showed chemical compatibility without the need for solvents as dispersants. These properties allow the application of coloured smectites as pigments in a sustainable circular economy.

The sorption properties of two layered minerals of the hydrotalcite supergroup – hydrotalcite and stichtite – were investigated with the aim of determining their kinetic parameters of sorption and their adsorption isotherm type. Pristine hydrotalcite and stichtite were characterized using X-ray diffraction, Fourier-transform infrared spectroscopy, scanning electron microscopy, energy-dispersive Х-ray analysis and laser diffraction analysis of the particle-size distribution. The ‘memory effect’ of the sorbents was examined after calcination at 650°C. Slight indications of reconstructed hydrotalcite were observed, while the stichtite dehydration–rehydration cycle was irreversible. The hydrotalcite and stichtite were used to remove Congo Red from the aqueous solution. The pseudo-second order kinetic model described the process adequately. Mixed external and internal diffusion was confirmed for both minerals. The sorption of Congo Red on stichtite fits the Langmuir model. Stichtite demonstrated a maximum adsorption capacity of 2.5 mmol g–1 at 35°C. Increasing temperature increased the adsorption rate of Congo Red on stichtite but did not affect the adsorption rate constant for hydrotalcite.

Mineral reactions in soils demonstrably take place on a human timescale. The weathering of silicate ‘rock-forming’ minerals releases nutrients that are essential for plant growth, including silica. This process consumes CO2, which is ultimately derived from the atmosphere, through enhanced rock weathering. From a human perspective, the weathering process has two beneficial functions – crop nutrition and climate mitigation – through the removal of atmospheric CO2. By considering these as a coupled process, the release of silica during weathering can be matched to what is taken from the soil by a crop (e.g. wheat). A simple analysis shows that the amount of silica that accumulates in wheat during a 4 month growing period is readily released by the weathering of pyroxene and plagioclase, minerals that commonly occur in basaltic igneous rocks. In contrast, the dissolution rate for quartz is so low that it cannot supply the silica taken up by the crop and is inert. Similarly, dissolution of clay minerals releases sufficient silica for plant uptake. Rapid weathering of silicate minerals within soils is evident from images of surfaces of grains exposed in soils for periods of 10–100 years. The evidence for silicate rock weathering as part of the soil system that sustains humanity is provided by the vegetation that we see around us.

Bentonite-based tablets offer multiple advantages over other types of formulated tablets, including being biocompatible and cost-effective, and they can be used to develop gel-like matrices that have potential for use in sustained-release formulations. Developing a high-load sustained-release formulation has been reported to be challenging; therefore, the aim of this study was to develop systematically bentonite-based sustained-release tablets for a high-load active agent (ibuprofen) and investigate their release kinetics. Ibuprofen-loaded tablets (800 mg) were prepared using wet and dry granulation followed by enteric coating of the tablets. Fourier-transform infrared spectroscopy, differential scanning calorimetry and X-ray powder diffraction were used to evaluate the compatibility of ibuprofen with bentonite. The results show that these tablets comply with compendial requirements. In addition, the release profile of the formulations reveals that the drug follows a non-Fickian release model. The present formulation demonstrates a new use of bentonite as a safe and cost-effective excipient with adequate binding and compaction for preparing sustained-release tablets.

The Nanjing Bao'ensi site is the largest and highest-ranking royal temple from the Ming Dynasty, and it is famous for its full-body glass pagoda. In this study, the glazed tiles excavated from the southern area of the Bao'ensi site were selected and analysed using X-ray diffraction, thermal dilation and energy-dispersive X-ray fluorescence to determine their phase composition, firing temperature and chemical composition. The glazed tile bodies of the Bao'ensi site consist mainly of quartz and mullite, although some samples contain trace amounts of other minerals. All of the body samples were fired to the same temperature range (i.e. 1000–1100°C). The firing temperature combined with the phase composition indicate that the raw materials and firing process of the glazed tile body samples have similarities, but there are certain differences. The source of the raw materials for a portion of the glazed tile bodies is Dangtu, Anhui, whilst the source of the raw materials for the remaining materials remains to be discovered.

This work studied the efficiency of Tamazert kaolinite clay for adsorbing the cationic dye crystal violet from an aqueous solution in a batch system. The kinetics of the process and the equilibrium of adsorption were studied using non-linear models. The characterization of Tamazert kaolinite clay showed that it has structural, textural and surface properties that are suitable for adsorption. The effects of various process parameters such as contact time, initial dye concentration, initial pH, adsorbent dose and temperature were tested. The kinetic study using non-linear regression showed that the pseudo-second order model best fitted the experimental data. The intra-particle model was also used to estimate the contribution of intra-particle diffusion to this process. The adsorption isotherms were fitted to Freundlich, Langmuir and Redlich–Peterson models, showing that the adsorption is limited to a monolayer with a monolayer adsorption capacity of 44.2 mg g–1. The thermodynamic study indicated that the process is exothermic, spontaneous and accompanied by a decrease in entropy.

High-whiteness kaolinite mining reserves are scarce. In some locations, it is necessary to remove material to access them (adding to the cost). Therefore, processes have been developed to eliminate contaminants, such as iron, and provide alternatives to the used contaminated materials that, after being treated, meet quality criteria. In our previous research, we developed an electrochemical process for kaolin whitening at the laboratory level and bench scale, demonstrating the reaction mechanisms that occur during the removal of iron from kaolin. However, the geometry used at the laboratory level does not present the most suitable position for the electrodes. Therefore, in the present study, we focused on the geometry and the function of the electrodes. This is necessary during the escalation process to reach the pilot-scale level. The study was carried out using computer-aided engineering in the COMSOL Multiphysics computer program and by analysing the distribution of the electric potential and the electric current of the geometries considered while performing the scaling. The results indicated that the change in the anode position from perpendicular to parallel to the discs improved the distribution of electric current density on the cathode surface and so increased the elimination of iron through electrochemical deposition. Similarly, to reduce the amount of material used in the construction of the reactor, the anode-size effect was analysed, revealing that relatively small anodes improved the distribution of electric current density over the entire surface of the electrode and not only at the edges.

Clay minerals are essential components of soil systems and understanding their role in soil structure and function is critical for soil environmental quality management and sustainable agricultural development. An in-depth study of clay minerals and the development of related materials is essential for a complete understanding and effective management of soil systems. This review is a detailed compilation of relevant studies over the past decade in this area, focusing on an overview of clay minerals and their modified materials and their regulation of soil structure and function. We focus on the direct influence of clay minerals on the physical, chemical and biological properties of soils, such as soil structure, soil fertility, plant growth, soil microbial activity and soil carbon sequestration. Finally, we concluded by summarizing the existing issues with clay mineral materials in soil improvement and by outlining potential future development trends and strategies.

In polymer composites, montmorillonite nanosheets are crucial as fire retardants, reinforcers, anti-corrosives, detoxifying agents and ultraviolet-protection agents. However, the quality of montmorillonite nanosheets can be improved by optimizing the raw bentonite purification process in which undesirable phases are removed. Optimization of Iranian calcium bentonite purification for nanomontmorillonite synthesis considering various parameters based on various physical approaches to dispersion and ultrasonication was investigated; the calcium bentonite purification was performed using sodium hexametaphosphate followed by either sedimentation or centrifugation, and the nanomontmorillonite synthesis was performed using ultrasonic treatment. The effects of suspension concentration, milling type, pH and centrifugation duration and speed on the separation of various impure phases were evaluated qualitatively and optimized. The raw and purified bentonite and the synthesized nanomontmorillonite were characterized using X-ray powder diffraction, X-ray fluorescence spectroscopy, Fourier-transform infrared spectroscopy and scanning electron microscopy. The cation-exchange capacity was also measured in the raw and purified samples. Optimal experimental conditions in the dispersed samples were achieved at a 2.5 wt.% concentration of bentonite suspension and planetary milling at pH 7. While the ultrasonic treatment was more effective than the dispersion approach for cristobalite elimination, a smaller lateral size of the montmorillonite sheets, optimized at 0.5 wt.% concentration of the suspension, was achieved. The increased cation-exchange capacity after the purification improved the exfoliation and delamination of montmorillonite nanosheets in the presence of cetyltrimethylammonium bromide as the surfactant. The interplanar spacing of (001) planes of 15 Å in raw bentonite shifted to 21 Å and 19 Å in purified and non-purified samples, respectively, after synthesis.

Clay-swelling inhibitors are often used to prevent the hydration of clay minerals, which can reduce the risk of wellbore instability and reservoir damage. The molecular behaviour of clay-swelling inhibitors at the montmorillonite–water interface is crucial for revealing their inhibition mechanisms and for evaluating and designing inhibitor molecules. N1,N1'-(ethane-1,2-diyl)bis(N1-(2-aminoethyl)ethane-1,2-diamine) (NETS), a low-molecular-weight clay-swelling inhibitor, is used widely to prevent clay swelling. Herein, the adsorption mechanism of NETS on the surface of montmorillonite (Mnt) was investigated using molecular dynamics (MD) simulations. In particular, the effects of molecular conformation and temperature on adsorption ability were investigated. The results show that the adsorption ability of NETS on the Mnt surface was affected significantly by the molecular conformation. Specifically, the dihedral angle of NETS adsorbed on the surface of Mnt decreases by ~20° and tends to adsorb on the surface of Mnt in a plane state. In addition, the adsorption stability of NETS on the Mnt surface decreased with increasing temperature, as was found using MD simulations. Detailed analysis shows that increasing temperature can lead to more frequent conformational changes, which weaken the interaction between NETS and Mnt, thus reducing adsorption stability. These molecular insights into the interaction mechanism between NETS and Mnt are beneficial for the evaluation of inhibitory effects and for the selection and molecular design of new clay-swelling inhibitors for use in drilling fluids.

The search for sufficiently high-quality clays for use in the tile industry represents a significant challenge. This study aimed to prepare Muttalip green clay tiles with flexural strengths adhering to the TS EN 1304:2016 standard. Muttalip green clay was subjected to sieving, vacuum pressed, dried and then baked to obtain galette tiles. The tiles were analysed subsequently using optical techniques, including X-ray diffraction, X-ray fluorescence spectrometry and field-emission scanning electron microscopy. The influence of various firing temperatures (900, 950 and 1000°C) on the flexural strength of the tiles was also investigated. The tiles obtained at 950°C exhibited a maximum flexural strength of 153.91 kg cm–2. Fourier-transform infrared spectroscopy revealed that the tiles reflect ultraviolet A radiation and absorb infrared radiation. Muttalip green clay is a suitable material for preparing tiles for roofing applications.

Uniaxial and isothermal compression tests of kaolinite were carried out using molecular dynamics simulations. Five different temperatures (300, 400, 500, 600 and 700 K) and pressures ranging from 0.0001 to 50 GPa were selected to study the temperature and pressure effects on the mechanical properties of kaolinite. As kaolinite may undergo a phase transition at ~1572 K, a highest temperature of 700 K was chosen to avoid such structural change. The Young's modulus, strength and elastic constants of kaolinite under various temperatures were calculated, and the relative change of the elastic constant C33 with temperature was found to be almost 12 times greater than the relative change of the interlayer constant C11. The microstructures under various compressive strains were tracked and they exhibited various failure modes in three directions. The temperature and pressure effects on the mechanical properties of three crystal directions were analysed. The results showed that the Young's modulus of the z-direction is the most affected by temperature; however, the influence of temperature on the strengths of the three crystal directions was the same. In addition, the structure of the z-direction was the most sensitive to temperature under the same hydrostatic pressure due to the weak interactions between layers.