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Silicate has been proven to be highly-effective at immobilizing soil heavy metals, but the effects of silicate stabilizers on rice grain cadmium (Cd) reduction and rice quality under field conditions are not clear. In this study, a field experiment was conducted over three consecutive years was conducted to examine the Cd reduction in rice grains and to reveal the potential effects of silicate stabilizers on rice grain nutrients, by setting different amounts of bentonite (B), silica‒calcium fertilizer (SC) and zeolite powder (ZP). The results revealed that the application of the B, SC and ZP significantly decreased the soil CaCl2‒Cd concentration (> 39%) and significantly reduced the grain Cd concentration in both early rice (> 70%) and late rice (> 18%) under field conditions; the silicate stabilizers reduced the soil available iron (Fe) but did not limit rice grain Fe nutrition. Additionally, the three silicates promoted rice yield and improved the rice grain Ca and Mg contents; and the application of B increased the amylose concentration of the late rice grains. In conclusion, high amounts of silicate stabilizers did not adversely influence the soil conventional nutrient indices, rice minerals or rice taste, but changes in rice selenium content need attention. Overall, in comparison with lime, silicate stabilizers can improve not only the safety of rice but also the nutritional and taste qualities of rice and are more eco-friendly for long-term use in soil. [ABSTRACT FROM AUTHOR]

In this study, the adsorption of dibenzothiophene sulfone (DBTO) was investigated using clay minerals as adsorbents. Raw bentonite (BR) and raw activated clay (ACR) were impregnated with Fe3+ and Fe6+, creating bentonite-Fe3+ (BF3), bentonite-Fe6+ (BF6), activated clay-Fe3+ (ACF3), and activated clay-Fe6+ (ACF6). The surface functional groups, surface morphology, and surface area of the raw and modified adsorbents were studied through Fourier transform infrared spectroscopy, a scanning electron microscope, and Brunauer, Emmett, and Teller analysis, respectively. Batch experiments on simulated oil were done to test the effect of adsorption time (0.5–24 h), adsorption dosage (0.3–1.5 g), and adsorption temperature (30–50 °C). The results of the experiments showed the suitability of the pseudo-second order kinetic model on the clay adsorbent and sulfone system. This suggests that chemisorption is the rate-limiting step of the reaction. Equilibrium isotherms indicated the adherence of DBTO onto BR and BF3 to the Freundlich model, implying the heterogeneous adsorption of the sulfones onto the adsorbents. The systems of DBTO with BF6, ACR, ACF3, and ACF6 showed a better fit with the Dubinin-Radushkevich model. This denotes that adsorption happens through the filling of sulfones of the micropores on the adsorbent. Lastly, thermodynamic studies revealed the endothermic and non-spontaneous nature of the clay adsorbents and sulfone systems. The experiments showed that the impregnation of Fe3+ and Fe6+ lowered the desulfurization ability of the adsorbents. This could be due to the iron ions being hard acids and the sulfones being soft bases, thus showing lower compatibility than the raw counterparts of the adsorbents. Comparison with related studies showed that the prepared adsorbents, namely BF3 (5.1 mg g−1) and BF6 (6.4 mg g−1), had a higher adsorption capacity than Ni2+-loaded activated carbon (4.9 mg g−1) and activated clay (4.1 mg g−1). The study shows that BR (7.2 mg g−1) is the best-performing adsorbent, which can be set as the direction for future research. This study is a step toward the commercialization of oxidative desulfurization methods. [ABSTRACT FROM AUTHOR]

Internal erosion by suffusion within a sand–clay mixture may occur as detachment of clay particles, which is induced by a decrease in ionic concentration (IC) along with application of a high hydraulic gradient. Through designed laboratory soil-column experiments, this study investigates the impact of the IC gradient (stepwise or gradual decrease), clay mineralogy, sand particle size and hydraulic gradient on the suffusion of a sand–clay mixture. The observed breakthrough concentration of clay particles revealed the substantial suffusion of a sand–clay mixture caused by a stepwise decrease in the IC for kaolinite and illite, while similar filtrated quantities of bentonite were observed for stepwise and gradual decreases in IC. In addition, the small-grained sand showed a relatively high susceptibility to suffusion by a stepwise decrease in IC, most likely because of the low reattachment of detached clay particles. The mass of filtrated clay particles evaluated from the area of the observed breakthrough curves in this study provides a clear insight into the need to incorporate the IC gradient when assessing the susceptibility to the suffusion of clay-containing soils. [ABSTRACT FROM AUTHOR]

Bentonite, used as a barrier material in landfill systems and the geological disposal of radioactive waste, undergoes various processes such as the cation exchange with landfill leachate and repository groundwater, desiccation shrinkage due to heat released from solid waste or nuclide decay. In the context of these engineering applications, it is crucial to consider the effect of interlayer cation composition on the desiccation-shrinkage behavior of bentonite for assessing the long-term performance of barrier systems. This study investigates this impact by conducting desiccation tests on four different cation-type bentonite samples (i.e., K-, Na-, Ca-, and Mg-bentonite) and elucidating the underlying mechanisms through mercury intrusion porosimetry test, X-ray diffraction analysis, and suction measurements. The results indicate that K-bentonite exhibits the highest water evaporation rate and the lowest shrinkage potential, with no shrinkage cracks detected, and that Na-bentonite evaporates water at a relatively fast rate but presents the most pronounced volumetric shrinkage. In contrast, Ca- and Mg-bentonite have the highest water-retention capacity, and their shrinkage potentials are less than Na-bentonite. An improved shrinkage model is proposed, which is shown to describe the measured shrinkage curves for four types of homoionic bentonite samples. Additionally, the mechanism behind the effect of different interlayer cations was interpreted in terms of the interlayer–cation–water interaction, pore structure evolution, and soil suction variation. [ABSTRACT FROM AUTHOR]

Suffusion refers to the loss of small particles in a soil matrix without volume changes, caused by hydrodynamic forces and alternation of pore fluid chemistry. This study investigated the ionic concentration (IC)-induced suffusion of sand–clay mixtures under saturated and unsaturated conditions through laboratory soil-column experiments. The impacts of clay mineralogy and sand-grain size on suffusion were investigated based on the breakthrough curves (BTCs) obtained from the soil-column experiments. In addition, the degree of saturation during the experiments was measured to assess the impact of the saturation state on suffusion in the sand–clay mixtures. The observed BTCs in this study demonstrated that suffusion was more significant under saturated conditions than unsaturated conditions for the sand–kaolinite and sand–illite mixtures. In contrast, the sand–bentonite mixtures exhibited higher susceptibility to suffusion under unsaturated conditions. Moreover, for the sand–kaolinite mixtures, a higher susceptibility to suffusion was observed with smaller sand-grain sizes under saturated conditions, whereas the opposite trend was observed under unsaturated conditions. This study provides insights into the suffusion behavior of sand–clay mixtures, considering influential factors such as clay type, sand-grain size, and IC gradient under both saturated and unsaturated conditions, which highlight the importance of considering the saturation state for a comprehensive understanding of suffusion in the sand–clay mixtures. [ABSTRACT FROM AUTHOR]

This research investigates the adsorption efficiency of a chitosan-bentonite (Ch–B) composite in removing methyl orange (MO), a common textile dye, from aqueous solutions. The study integrates experimental and theoretical analyses, employing density functional theory (DFT) to gain insights into the molecular interactions between the composite material and MO molecules. The Ch–B composite was characterized using various techniques, including FT-IR spectroscopy, XRD, and SEM–EDX. The experimental results indicate that the Ch–B composite exhibits a high adsorption capacity for MO, with optimal conditions identified for efficient removal. The Langmuir model was found to best fit the experimental data and the adsorption capacity was 117 mg g−1. Adsorption thermodynamics showed that the adsorption process was spontaneous, feasible, and exothermic. DFT calculation results are correlated with experimental findings to confirm theoretical predictions and improve the overall understanding of the adsorption process. Electronic structure calculations reveal the nature of the interactions between the Ch–B composite and MO molecules, including hydrogen bonds and electrostatic forces. [ABSTRACT FROM AUTHOR]

The bentonite clay has been activated by acid treatment and utilized as a lower‐cost and eco‐friendly adsorbent required to remove Fast Green FCF dye from the aqueous solution. At first acid activated bentonite clay minerals were analyzed by various analytical techniques like Fourier Transform Infrared Spectroscopy (FTIR), x‐ray diffraction (XRD), and x‐ray fluorescence (XRF) analysis. The batch adsorption research was performed to investigate the Fast Green FCF dye adsorption onto the acid‐treated (Bent) bentonite clay. Sorption studies investigated the impacts of adsorbent dosage, initial pH, and time of contact on Fast Green FCF color elimination. The adsorption capacity decreased as the pH was above 7 and then remained almost the same after a pH value of 9. At acidic conditions (below pH value 7), the capacity of adsorption diminished by a decrease in the pH of the solution. The results indicated that the maximum capacity of adsorption has been obtained at an adsorbent dosage of 0.1 g. As the dosage of the adsorbent was improved, several active sites that were available at the time of the dye adsorption increased. As a result, the dye percentage that was removed from the clay increased. Besides these, adsorption kinetics, adsorption equilibrium isotherm, and thermodynamics studies have been also conducted. While studying the adsorption kinetics pseudo‐2nd‐order kinetics has been seen to be more appropriate as compared to pseudo‐1st‐order model. The experimental findings indicated that the attachment of the dye to the clay surface followed the "Langmuir adsorption" isotherm rather than the Freundlich adsorption isotherm with a monolayer coverage of 18.93 mg/g. From the thermodynamics study, it was revealed that the process of adsorption takes place instantly at high temperatures. [ABSTRACT FROM AUTHOR]

In this research, a suitable and efficient CoFe2O4@ZnO@Bentonite nano-catalyst was designed and synthesized by using zinc oxide (ZnO) and cobalt ferrite (CoFe2O4) nanoparticles and bentonite by microwave irradiation. Characteristics of the synthesized nanocomposite were investigated by Fourier transform infrared (FT-IR), scanning electron microscope (SEM), energy dispersive X-ray (EDX), transmission electron microscope (TEM), X-ray diffraction (XRD), Bruner-Emmett-Teller (BET) and vibrating sample magnetometer (VSM) techniques. The produced catalyst was effectively employed as a supported solid acid catalyst in mildly agitated three-component reactions involving aromatic aldehydes, 4-hydroxycoumarin, and 1,3-dimethyl-barbituric acid in a single pot to produce benzylbarbiturocoumarins. Starting materials were condensed via three C-C bond formation by CoFe2O4@ ZnO@Bentonite as an efficient, recyclable, and environmentally safe nanocatalyst to obtain target products. The advantages of this method include using a natural substrate, small amounts of catalyst, aqueous media, performing reactions at ambient temperature, simple separation and purification of products, and good yields with short reaction times. [ABSTRACT FROM AUTHOR]

Bacterial biopolymers are polymeric materials that are produced by microorganisms. Due to its inherent brittleness and slow crystallization rate, it has limited industrial applications. Polyhydroxybutyrate (PHB) composites have been created to tackle these problems by combining non‐modified clay and organically modified nanoclay. In this study, 3 wt % of two different kinds of clays were incorporated to PHB through melt mixing method to prepare composites of PHB/bentonite Clay (BC) and PHB/organically modified nanoclay (Cloisite 30B (C30B)). The characteristics of PHB and its composites were investigated to study their thermal, rheological, morphological, surface properties and biodegradability. The study showed that the incorporation of C30B and BC into the PHB matrix improved the crystallization temperature to 97.30 and 96.82°C respectively as compared to the crystallization temperature of the PHB matrix as 88.79°C. The increased result of storage modulus (G') and loss modulus (G") in its rheological analysis confirmed that there was proper melt intercalation in case of both PHB/C30B and PHB/BC composite. The morphological characteristics results provide less coagulation and good clay distribution over the polymer matrix which leads to improved contact angle of 66.60° and 68.15° in case of PHB/BC and PHB/C30B respectively. Further both the composites and PHB film showed biodegradation characteristics. In the realm of nanocomposite films for various applications, where the cost is the major consideration, the PHB/BC composite films are promising economical solution in place of high cost PHB/C30B nanocomposite films. Highlights: The BC/PHB and C30B/PHB composite films were developed using a micro‐compounder.Each films having a thickness 0.6 mm was extruded using a die.Uniform dispersion of clay is characterized from SEM.PHB with clay, boosted complex viscosity, storage, and loss modulus.PHB decomposes readily in compost, as do PHB/C30B and PHB/BC composites. [ABSTRACT FROM AUTHOR]

The viscosity of the same natrium-based bentonite produced by different manufacturers varies greatly when the self-setting mortar is prepared with the same ratio. The essence of the viscosity is caused by the discordant microstructure of the material. Based on SEM, XRD, EDS and NMR microscopic tests, the same bentonite produced by two different manufacturers and its self-coagulated mortar were analyzed, and the viscosity microscopic mechanism was studied. The main conclusions are as follows: a) For the two bentonite grout, the viscosity is thixotropic. The establishment of "card palace" and the formation of Q4 structure will increase the viscosity, while shear will destroy the microstructure and reduce the viscosity. The content of bentonite montmorillonite from Xiangyuan is higher than that from Yulong soil, so its slurry viscosity is higher than that from Yulong soil as a whole. b) Agitation and low shear promote the dispersion of montmorillonite particles in small lamella. The more the dispersion of small lamella, the higher the viscosity of bentonite slurry after stopping shearing. c) For bentonite self-coagulant slurry, its viscosity changes mainly depend on the degree of internal charge adsorption and hydration reaction, and the C-SH gel generated by hydration reaction can promote the increase of slurry viscosity. d) The calcium carbonsulphosilicate generated in the process of condensation is not conducive to the formation of C-S-H gel. The content of calcium carbonsulphosilicate in Xiangyuan soil mortar is higher than that in Yulong soil mortar, so its overall viscosity is lower than that in Yulong soil mortar. [ABSTRACT FROM AUTHOR]

Bentonite plastic concrete (BPC) is extensively used in the construction of water-tight structures like cut-off walls in dams, etc., because it offers high plasticity, improved workability, and homogeneity. Also, bentonite is added to concrete mixes for the adsorption of toxic metals. The modified design of BPC, as compared to normal concrete, requires a reliable tool to predict its strength. Thus, this study presents a novel attempt at the application of two innovative evolutionary techniques known as multi-expression programming (MEP) and gene expression programming (GEP) and a boosting-based algorithm known as AdaBoost to predict the 28-day compressive strength () of BPC based on its mixture composition. The MEP and GEP algorithms expressed their outputs in the form of an empirical equation, while AdaBoost failed to do so. The algorithms were trained using a dataset of 246 points gathered from published literature having six important input factors for predicting. The developed models were subject to error evaluation, and the results revealed that all algorithms satisfied the suggested criteria and had a correlation coefficient (R) greater than 0.9 for both the training and testing phases. However, AdaBoost surpassed both MEP and GEP in terms of accuracy and demonstrated a lower testing RMSE of 1.66 compared to 2.02 for MEP and 2.38 for GEP. Similarly, the objective function value for AdaBoost was 0.10 compared to 0.176 for GEP and 0.16 for MEP, which indicated the overall good performance of AdaBoost compared to the two evolutionary techniques. Also, Shapley additive analysis was done on the AdaBoost model to gain further insights into the prediction process, which revealed that cement, coarse aggregate, and fine aggregate are the most important factors in predicting the strength of BPC. Moreover, an interactive graphical user interface (GUI) has been developed to be practically utilized in the civil engineering industry for prediction of BPC strength. [ABSTRACT FROM AUTHOR]

To elucidate the time-dependent swelling behavior of landfill sand-bentonite mixture liners under the effect of organic pollutants, an no loading swelling ratio test was conducted on mixtures with varying sand and diesel content. The evolution characteristics of the swelling time curve morphology were investigated. The micro-mechanisms underlying the swelling time effect evolution were explored. The results indicated that the sand-diesel interaction significantly altered the swelling time curve morphological characteristics of the mixture. As the sand content increased, the swelling coefficient at the stable state decreased. However, during the rapid swell phase, dieselcontaminated mixed soil does not exhibit the increase-then-decrease pattern in swell coefficient seen in unpolluted mixed soil. The duration of both the slow swelling phase and the time to reach a stable state were longer. Mechanistic analysis revealed that cation exchange capacity is insufficient to effectively analyze the evolution characteristics of the swelling time curve. Instead, the initial swelling potential of bentonite is the true indicator of the mixture’s swelling properties. The particle size distribution influences the changes in the swelling coefficient during the rapid swelling phase, but diesel alters the particle size distribution, mitigating its impact. The oil sealing effect within intra-aggregate and inter-aggregate pores not only weakened the swelling characteristics of the mixture at all stages but also increased the permeability resistance, thereby reducing the duration of the rapid swelling phase and extending the slow swelling and stable swelling phases. [ABSTRACT FROM AUTHOR]

Hydraulic conductivity tests were conducted on six bentonite-polymer (B–P) geosynthetic clay liners (GCLs) to investigate the effect of the slow cation exchange process and polymer elution on the long-term hydraulic conductivity of B–P GCLs. Tests were conducted up to 1458 days and as many as 443 pore volumes of flows (PVFs). Three B–P GCLs consist of linear polymer whereas the other three have crosslinked polymer. One sodium geosynthetic clay liner (Na–B GCL) was used as a control. Hydraulic conductivities (K 6766) of B–P GCLs (5.4 × 10−12 m/s to 3.7 × 10−11 m/s) per ASTM D6766 were approximately 2-3 orders of magnitude lower than that of Na–B GCL (2.3 × 10−9 m/s to 3.5 × 10−9 m/s). Tests were continued after hydraulic and chemical equilibrium to investigate the long-term hydraulic conductivity of GCLs. Hydraulic conductivities of GCLs had an increasing trend after hydraulic and chemical equilibrium. The ratio of K L /K 6766 for B–P GCLs was 3.5–14.7, whereas ratio of K L /K 6766 for Na–B GCLs was 1.0–1.7. Total organic carbon (TOC) tests results confirmed that polymer elution occurred during the entire permeation process. The higher ratio of K L /K 6766 for B–P GCLs was attributed to the effect of polymer elution. • Hydraulic conductivity tests were conducted up to 4 years to test long-term hydraulic conductivity of B–P GCLs. • The ratios of K L /K 6766 for B–P GCLs to synthetic CCP leachate were higher than that of Na–B GCLs (e.g., 3.5 to 14.7 vs. 1.7). • Polymer elution from B–P GCLs affects the long-term hydraulic conductivity of B–P GCLs. • The polymer elution should be measured and considered as an additional termination criterion in ASTM D6766. [ABSTRACT FROM AUTHOR]

The self-healing capacities of a GCL with natural bentonite (NB) as core (NB-GCL) and a GCL with a polymerized bentonite (PB) as core (PB-GCL) were investigated under simulated field conditions, i.e. geomembrane-GCL-a clayey subsoil layer composite liner system with a damage hole on the geomembrane and the GCL. The clayey subsoils tested had initial water contents of 22.2% and 26.8%. The liquids used were deionized (DI) water and 0.3 M NaCl solution. The test results indicate that for both the PB-GCL and NB-GCL only hydrated on the subsoils for 1–3 months, a damage hole of 15 mm in diameter was almost not self-healed. For cases of applying a constant liquid head on the top of the geomembrane of 100 mm, the sizes of damage holes were self-healed in term of diameter is about half of the values reported in the literature for tests with plenty liquid supply to the damaged GCLs. Further, for the conditions tested and for the cases self-healed, DI water leaked into the subsoil was less than about 60 g, and 0.3 M NaCl solution leaked was less than 150 g. • Self-healing capacity of GCLs was newly studied under a simulated field condition. • GCLs hydrated on clayey subsoils had very limited self-healing capacity. • Self-heling capacity of GCLs with limited liquid supply was clarified. • Leakage through a hole on GCL before it was self-healed was novelly investigated. [ABSTRACT FROM AUTHOR]

Two series of experiments were carried out to examine pressurised bentonite slurry infiltration into saturated sand columns. Three types of sand were examined, and water–bentonite and water–bentonite–sand slurries were used in series 1 and 2, respectively. Series 1 investigated the effect of sand particle size and series 2 examined the effect of the fine-sand particle content in the slurry. Scanning electron microscopy (SEM) imaging was used to observe the morphological features of the dry slurry-infiltrated sand samples. A solution for the infiltration distance during mud spurt for water–bentonite–sand slurry infiltration was verified using the data from series 2. The infiltration test results showed that the hydraulic conductivity of the slurry-infiltrated coarse sand for slurry in series 2 was lower than that in series 1. Visual observations and the SEM images showed that sand particles were bound to a bentonite film, indicating that, during infiltration, the channels for fluid flow among the sand particles are blocked by the bentonite particles adhered to the sand particles. The solution for the infiltration distance during mud spurt for water–bentonite–sand slurry infiltration showed good agreement with the experimental results. [ABSTRACT FROM AUTHOR]

The study of the thermokinetics of two types of wheat straw pellets, T1 (100% wheat straw) and T2 (70% wheat straw, 10% each of bentonite clay, sawdust, and biochar), under a nitrogen atmosphere (31–800 °C and 5, 10, and 20 °C/min heating rates) using model-free and model-based approaches by TG/DTG data, revealed promising results. While model-free methods were not suitable, model-based reactions, particularly Fn (nth-order phase interfacial) and F2 (second-order) models, effectively described the three-phase consecutive thermal degradation pathway (A→B, C→D, and D→E). The activation energy (Eα) for phases 2 and 3 (Fn model) averaged 136.04 and 358.11 kJ/mol for T1 and 132.86 and 227.10 kJ/mol for T2, respectively. The pre-exponential factor (lnA) varied across heating rates and pellets (T2: 38.244–2.9 × 109 1/s; T1: 1.2 × 102–5.45 × 1014 1/s). Notably, pellets with additives (T2) exhibited a higher degradable fraction due to lower Eα. These findings suggest a promising potential for utilizing wheat straw pellet biomass as a bioenergy feedstock, highlighting the practical implications of this research. [ABSTRACT FROM AUTHOR]

The Upper Cretaceous Cantwell Formation in Denali National Park and Preserve (DENA) preserves an abundant and diverse ichnofossil record of high latitude dinosaurs. Field-based investigations of the formation remain limited due to its wide areal extent and remoteness, leaving questions concerning its temporal and faunistic relationships to other units unaddressed. Here we describe the largest tracksite known in DENA and all of Alaska – a 7500 square metre outcrop of steeply dipping beds known as the Coliseum. The site exposes 66.3 metres of vertical section consisting of laterally extensive fine- to medium-grained sandstone, mudstone, calcareous shale, and bentonite. Vertebrate trace fossils include true tracks, transmitted tracks, natural casts, and trackways documented via handheld and UAV-assisted photogrammetry, enabling three-dimensional mapping of the site. Facies analysis reveals a depositional environment of crevasse splay and overbank deposits within a fluvial floodplain. U-Pb dating of bentonite collected from the site returned an age of 69.3 ± 0.9 Ma, improving the limited temporal constraints of the formation. We document several ichnotaxa, some new to the formation, representing ornithopods, ceratopsids, and large and small-bodied avian and non-avian theropods. The Coliseum provides a rare window into a high latitude, Late Cretaceous forested ecosystem deposited in a Greenhouse World. [ABSTRACT FROM AUTHOR]

Bentonite-sand mixture is considered to be a potential liner material for landfill facilities owing to its excellent sorption potential and swelling characteristics. Such liner materials are expected to perform satisfactorily if the hydraulic conductivity is maintained less than 10−7 cm/s and thereby inhibiting the migration of the generated leachate. However, the performance assessment of these liners in the presence of highly concentrated organic fluids and under the overburden stresses that is usually expected in landfill conditions is scarce. Therefore, in the present work, the hydraulic performance of the bentonite-sand mixtures in the presence of the organic compounds commonly encountered in the landfill leachate is studied, which is a need of the hour. Flow tests were performed to evaluate the hydraulic conductivity of different bentonite-sand mixtures in unhydrated conditions and permeated with varied proportions of methanol-water and ethanol-water mixtures. The study reveals that the proportions of the organic pore fluids significantly influence the hydraulic conductivity of the bentonite-sand mixtures. A very good linear relationship was observed between the pore fluids' dielectric constants and the hydraulic conductivity of the bentonite-sand mixtures. The chemo-mechanical behavior suggests that the conventional bentonite-sand mixtures perform poorly in terms of the hydraulic and swelling characteristics with the change in the dielectric constant of the organic fluids. The microstructural analysis also supports the experimental findings that as the dielectric constant of the fluid are reduced, the effective flow path through the soil increases considerably resulting in higher hydraulic conductivity. [ABSTRACT FROM AUTHOR]

This study aims to synthesize bentonite/PDA/Fe3O4@CuO composites as a catalyst for the photodegradation of Methylene blue dye. Composite characterization involves X-ray Diffractometry (XRD), Scanning Electron Microscopy (SEM) with X-ray Energy Dispersion Spectrometry (EDS), UV-Vis Diffuse Reflectance Spectroscopy (UV-Vis DRS), and Vibrating Sample Magnetometer (VSM). Response Surface Methodology (RSM) employs Central Composite Design (CCD) to optimize photodegradation by varying dye concentration, irradiation time, and catalyst dose. The bentonite/PDA/Fe3O4@CuO composites exhibit a saturation magnetization value of 54.82 emu/g and a band gap of 2.1 eV. The optimization revealed that concentration and dose significantly impact the photodegradation efficiency. A quadratic model is suitable for modeling the photodegradation of Methylene blue dye using bentonite/PDA/Fe3O4@CuO composites, as determined by analysis of variance (ANOVA). The optimal conditions for achieving maximum photodegradation efficiency were identified as a dye concentration of 10 mg/L, an exposure time of 90 min, and a catalyst dose of 1.67 g/L. Under these parameters, the photodegradation process exhibited a remarkable efficiency of 100%. The Bentonite/PDA/Fe3O4@CuO composites exhibited strong stability, efficiency, and recyclability. After six photodegradation cycles, there was a 5.18% decrease in photodegradation efficiency. [ABSTRACT FROM AUTHOR]

In some countries lacking sodium bentonite (NaB), polymer-modified calcium bentonite (CaB) has attracted attention for its application in sand-bentonite slurry trench cutoff walls to control groundwater contamination. Thus, this study used polyanionic cellulose (PAC), an environmentally friendly hydrophilic polymer, to modify CaB. The hydraulic and consolidation properties of cutoff-wall materials (including bentonite cake and backfill) containing CaB or modified CaB with 4% PAC (dry mass ratio, 4%PAC-CaB) under various stress conditions, CaCl2 solution concentrations, and bentonite contents were investigated through a series of experiments, including modified fluid loss, slump, Atterberg limit, oedometer, and rigid-wall hydraulic conductivity tests. The results show that the 4%PAC-CaB cake had better salt resistance and impermeability than CaB and NaB cakes under different stress and salt concentration conditions, and sand-4%PAC-CaB backfill had a significantly higher liquid limit, ideal water content, and compression index, and a lower coefficient of consolidation and permeability than sand-CaB backfill with the same bentonite content. More importantly, the addition of 4% PAC had a more significant effect on decreasing the permeability of the sand-CaB backfill than increasing the CaB content. Overall, 4%PAC-CaB is a promising modified CaB that can replace NaB for the construction of cutoff walls with excellent impermeability. [ABSTRACT FROM AUTHOR]

The physicochemical properties of natural bentonite and its sorbents were studied. It has been established the modification of natural bentonites using polyhydroxoxides of iron (III) (mod.1_Fe_5-c) and aluminum (III) (mod.1_Al_5-c) by the "co-precipitation" method led to changes in their chemical composition, structure, and sorption properties. It was shown that modified sorbents based on natural bentonite are finely porous (nanostructured) objects with a predominance of pores of 1.5–8.0 nm in size. The modification of bentonite with iron (III) and aluminum compounds by the "co-precipitation" method also leads to an increase in the sorption capacity of the obtained sorbents with respect to bichromate and arsenate anions. A kinetic analysis showed that, at the initial stage, the sorption process was controlled by an external diffusion factor, that is, the diffusion of the sorbent from the solution to the liquid film on the surface of the sorbent. The sorption process then began to proceed in a mixed diffusion mode when it limited both the external diffusion factor and the intra-diffusion factor (diffusion of the sorbent to the active centers through the system of pores and capillaries). To clarify the contribution of the chemical stage to the rate of adsorption of bichromate and arsenate anions by the sorbents under study, kinetic curves were processed using equations of chemical kinetics (pseudo-first-order, pseudo-second-order, and Elovich models). It was found that the adsorption of the studied anions by the modified sorbents based on natural bentonite was best described by a pseudo-second-order kinetic model. The high value of the correlation coefficient for the Elovich model (R2 > 0.9) allows us to conclude that there are structural disorders in the porous system of the studied sorbents, and their surfaces can be considered heterogeneous. Considering that heterogeneous processes occur on the surface of the sorbent, it is natural that all surface properties (structure, chemical composition of the surface layer, etc.) play an important role in anion adsorption. [ABSTRACT FROM AUTHOR]

The volcanism that took place during the Neogene in the southeastern Iberian Peninsula caused a large accumulation of volcanosedimentary materials, which were subsequently altered and transformed into bentonite deposits. The mineral composition and technical quality of these deposits have been demonstrated and established in this work. The main object of this research is the mineral, chemical and thermal characterization of the bentonites that lie in the southeastern region of Spain and to demonstrate their technical capabilities to be used as pozzolans. The first phase of characterization of the samples was carried out by X-ray diffraction (XRD), oriented aggregates (OAs), X-ray fluorescence (XRF) and thermogravimetric analysis (TGA). In the second phase, a chemical–technical quality test (CTQT) was carried out, aimed at determining reactive SiO2 and reactive CaO, whereas in the third phase, a chemical pozzolanicity test (CPT) was carried out to establish the pozzolanic behavior of the samples over two test periods: 8 and 15 days. The XRD and OA analyses showed that the bentonite samples are made up of a main phase formed by montmorillonite, quartz, plagioclase-albite and chabazite–Ca. The results obtained by XRF on the bentonite samples indicated that the SiO2 contents are high and vary between 43.33% and 64.71%, while Al2O3 ranges between 15.81% and 17.49%. The CTQT established that more than 80% of the SiO2 and CaO present in the samples are reactive, which was confirmed by the results of the chemical pozzolanicity test (CPT). The results obtained show that the bentonites in this study present technical qualities that are undoubtedly reinforced by their mineral constitution and chemical composition. These tests could become a practical guide for the selection of eco-efficient materials in the production of pozzolanic cements and environmentally friendly ceramic products. [ABSTRACT FROM AUTHOR]

In the present work, an investigation on the influence of the chemical environment on the sedimentation behaviour of bentonite suspensions is performed with particular reference to the effect of lime addition on the clay particle arrangement. The role of lime content, cation valence and source of calcium ions is considered in the experimental work. At the microscale, particle interaction is analysed by means of zeta potential measurements. Soil fabric formation during sedimentation and its physical properties are inferred from dynamic light scattering measurements, sedimentation tests and Atterberg limits. The addition of cations to pore water promotes the flocculation of montmorillonite particles favouring the formation of particle aggregates, whose dimension depends on ion valence and concentration. The final height of sediments reflects the combined effect of the mutual interactions among particles and the development of secondary phases due to pozzolanic reactions. The influence of clay mineralogy and its effects on the physical properties of lime-treated bentonite is highlighted by comparison with experimental evidence on lime-treated kaolin. [ABSTRACT FROM AUTHOR]

This work is based on a detailed study of samples from three industrial bentonite deposits in Russia (10th Khutor, Zyryanskoe) and Kazakhstan (Taganskoe). The samples of the listed bentonites were undergoing stage-by-stage purification from carbonates, organic matter, and non-clay iron-bearing phase procedures. The conducted research revealed changes in the composition of bentonites already at the first stage of purification, which, however, were not noted for all bentonites, as well as a change in the forms of Fe in smectite structure. The latter is probably associated with changes in cis- and trans-vacant positions. Sorption characteristics with respect to 137Cs are determined using the localization and charges in the smectite layer and the slight changes during purification, along with the specific surface area indicators. [ABSTRACT FROM AUTHOR]

Understanding the acoustic characteristics of hydrates in various sediments is crucial for hydrate resource detection and safe and efficient exploitation, as hydrate occurrence patterns vary greatly in different sediments. In this work, sediments with different bentonite contents, water saturations, and types were prepared to investigate the characteristics of P-wave velocity (reflecting the magnitude of hydrate saturation in the sediment) and amplitude (reflecting the degree of hydrate-sediment cementation) during hydrate formation and depressurization. During hydrate formation, the P-wave velocity and amplitude have similar trends. As clay content increases, the P-wave velocity increase rates quickened. On the other hand, the increased rate of P-wave velocity slows down with the increase of water saturation in the clay-bearing sediments. Comparing various types of sediment shows that the water absorption and swelling of bentonite reduce the pore space, speeding up the cementation of the hydrate with the sediment and increasing P-wave velocity at a faster rate. Correspondence between P-wave velocity and hydrate saturation is strongly related to sediment type, clay content, and water saturation. The rapidly decreasing amplitude in the early stage of hydrate depressurization indicates that hydrate in clay-bearing sediments is weakly cemented to the sediments, which is prone to stratigraphic instability. The findings of this study offer guidance for hydrate resource assessments in clay-bearing sediments as well as geologic risk estimations during hydrate mining. [ABSTRACT FROM AUTHOR]

Dialkylated diphenylamine, renowned for its exceptional thermal stability and antioxidant activity, are extensively used as antioxidants. Raw bentonite after acid-treatment was carried out and the catalytic performance of various solid acid catalysts was tested, and acid-treated clay exhibited the best. In addition, the relationship between catalytic activity and washing times has been explored. The results revealed that after activating by sulfuric acid and several water-treatment times, the catalytic activity and mono-selectivity of raw bentonite significantly improved. The acid-treated bentonite catalysts were investigated by BET, XRF, XRD, SEM, Raman and FT-IR, and results indicated that the Si/Al ratio and the specific surface area increased and the basal spacing was expanded after acid and water treatment. Finally, the deactivation (reusability and regeneration) of catalysts was studied, after characterized the fresh and used catalysts, the results indicated that the deactivation of catalysts was due to reduction of microporous structure and surface acidity. [ABSTRACT FROM AUTHOR]

The technical note presents findings of an experimental study on the applicability of equivalent intergranular void ratio e*eq concept in sand-plastic fines mixtures under monotonic and cyclic loading. The results of undrained triaxial tests conducted on mixtures of Hostun sand with varying amounts (0% to 20%) and types of plastic fines (kaolin and calcigel bentonite) were already presented in two previous studies. The e*eq for the mixtures under various initial densities was calculated using the parameter b. Preliminary results show that the concept of e*eq seems to hold valid in the e-p space considering monotonic tests as well as being able to capture the variation of the cyclic resistance ratio for a predefined number of cycles to initial liquefaction from cyclic undrained tests even in mixtures with plastic fines below threshold fines content. However, the need for further studies is duly acknowledged. [ABSTRACT FROM AUTHOR]

Expansive soils poses significant challenges in civil engineering projects, yet construction on them in many circumstances is unavoidable. Soil modification, therefore, is one of the finest options for improving the expansive properties of such soils. This study uses commercially available Sodium Bentonite as an expansive soil, where Recycled Glass Powder (RGP) alone and in combination with Polypropylene Fiber (PPF) are used as modifiers. RGP in the percentages of 5%, 10%, 20%, and 30% by dry weight, and 20% RGP in combination with PPF in the proportions of 0.25%, 0.5%, and 1.0% by dry weight of the soil sample were used in the study. Various tests to evaluate the index and engineering properties of both virgin and modified soil samples were carried out, including Atterberg limits, linear shrinkage (LS), specific gravity, compaction, free swelling index (FSI), expansivity index (EI), and one-dimensional consolidation test. Moreover, scanning electron microscopy and zeta-potential test were carried out to analyze the microstructural and electrokinetic properties of modified soil. The results demonstrated a significant decrease in LS (35.43%), FSI (62.23%), EI (50.29%), swelling index (37%), and compression index (22%) with the addition of 30% RGP. Furthermore, incorporating 1% and 0.5% PPF showed a remarkable decrease in LS (50%), and EI (31.78%), respectively as compared to the base soil mix with 20% RGP. Overall, recycled glass powder (RGP) and polypropylene fiber (PPF) as modifying agents hold strong potential for enhancing the expansive and swelling properties of highly expansive bentonite clay, offering promising solutions for construction challenges associated with expansive soils. [ABSTRACT FROM AUTHOR]

The reuse of solid wastes has awakened much attention and triggered extensive research, especially given the fact that kitchen waste (KW) and waste bentonite as typical solid wastes are increasing rapidly worldwide. In this work, the KW and waste bentonite were co-valorized to produce KW-bentonite (KWB) adsorbent at the mass ratio of 7:3 at 1000 °C. The effects of adsorbent dose, solution pH, and coexisting substances on the phosphate removal by KWB adsorbent were explored in a batch system, achieving the maximum adsorption capacity of 23.04 mg/g. Besides, it could be seen that the adsorption process of phosphate by KWB adsorbent depends on chemisorption through the analysis of thermodynamic and kinetic results. The properties of KWB adsorbent were analyzed to explore the adsorption process while an economic analysis was conducted to identify the practical application potential of KWB adsorbent for P-contaminated wastewater. In conclusion, the present study not only offers new insights into the synergistic effect of kitchen waste and waste bentonite for environmental pollution control, but also provides a feasible waste-to-wealth strategy for converting kitchen waste and waste bentonite into KWB adsorbent that can be used as an effective phosphate adsorbent. [ABSTRACT FROM AUTHOR]

The rise in demand for iron- and steel-based products globally has resulted in the depletion of high-grade iron ores, high energy consumption, and CO2 emissions. The world is rich in low-grade ores that have not been exploited, and this study aims to develop a feed for cast iron production, goethite ore–carbon composite pellets. A pelletizing disc was used to make the pellets followed by induration in a muffle furnace at 1373 K for 25 min, and the results showed that goethite–carbon composite pellets with the desired physical properties of a drop index greater than 4, dry compression strength greater than 2.2 kg/pellet, and an indurated compression strength above 250 kg/pellet could be produced by controlling the coal, limestone, and ethyl hydroxyethyl cellulose, avoiding the addition of impurities from bentonite. About 0.4 wt.% ethyl hydroxyethyl cellulose could be added to achieve the optimum strength in the composite pellets with a binary basicity of 0.27 and coal addition of 2.5 wt.%. A total metal recovery of 48.46% was achieved from the preliminary smelting experiments on the furnace burden, with a binary basicity of 1.3 at 1673 K with 25 min holding time and a carbon-to-oxygen ratio (wt.%) of 1.4 using an induction furnace. These composite pellets can potentially be used as a raw material for cast iron production towards the decarbonization of the steel industry. [ABSTRACT FROM AUTHOR]

The "sol–gel method" was used to prepare spherical chitosan-modified bentonite (SCB) hydrogels in this study. The SCB hydrogels were characterized and used as sorbents to remove tetracycline (TC) from aqueous solutions. The adsorbents were characterized by SEM, XRD, FTIR, TG, and BET techniques. Various characterization results showed that the SCB adsorbent had fewer surface pores and a specific surface area that was 96.6% lower than the powder, but the layered mesoporous structure of bentonite remained unchanged. The adsorption process fit to both the Freundlich model and the pseudo-second-order kinetic model showed that it was a non-monolayer chemical adsorption process affected by intra-particle diffusion. The maximum monolayer adsorption capacity determined by the Langmuir model was 39.49 mg/g. Thermodynamic parameters indicated that adsorption was a spontaneous, endothermic, and entropy-increasing process. In addition, solid–liquid separation was easy with the SCB adsorbent, providing important reference information for the synthesis of SCB as a novel and promising adsorbent for the removal of antibiotics from wastewater at the industrial level. [ABSTRACT FROM AUTHOR]

Globally, bentonite is being used as a binder in iron ore pelletizing due to its high swelling index, thermal resilience, and water absorption capacity. However, the conventional use of bentonite contributes to increased gangue content (Al2O3 and SiO2) in pellets, subsequently affecting blast furnace operations in terms of high solid fuel consumption, low productivity, and high slag rates. In this work, sodium hydroxide has been used with bentonite to reduce its consumption without affecting the pellet properties. Pellets are prepared by varying the NaOH addition from 0 to 0.1 pct at an interval of 0.02 pct. Green and fired pellets were tested for green compressive strength (GCS), dry compressive strength (DCS), drop number, cold compressive strength (CCS), Hoogoven simulations (HOSIM), softening-melting, and swelling index (SI). The interaction between hematite and bentonite was studied using molecular modeling simulations (ReaxFF MD). Microstructural studies (optical and SEM-EDS) of pellets were carried out for phase quantification and to assess the chemical composition of slag phases. Besides, FactSage simulations were performed to validate the slag phase formation. It is inferred that a 50 pct reduction in bentonite consumption is possible at 0.04 pct NaOH with a 12 pct improvement in CCS. Laboratory results were validated for a seven-million-tonne pellet plant with 0.02 and 0.04 pct NaOH dosage. Plant trial shows that there is an 18 and 39 pct reduction in bentonite consumption with the addition of 0.02 and 0.04 pct NaOH dosages, respectively. [ABSTRACT FROM AUTHOR]

Geochemical reactions and anthropogenic activities are a source of heavy metal concentration in aquatic bodies leading to serious detrimental effect to the environment because of its non-biodegradability. Bentonite, a smectite group of minerals has layered structure based on sheets having 2:1 structure i.e. one octahedral sheet sandwiched by 2 tetrahedral sheets. The bentonite was characterised by PXRD, FTIR, TGA and DSC experiments and the surface area was known by BET analysis. A weight loss of 14% and diffraction pattern of PXRD confirmed presence of Montmorillonite unit in the inner part. Bentonite acts as a natural scavenger of heavy metal toxicants.Owing to high cation exchange capacity, high surface area and intercalation properties, bentonite mineral has been used as a potential remover of heavy metals. The kinetic and thermodynamic studies were done in order to determine the remediation potential at pH 2 to 8. Langmuir, Freundlich and Temkin adsorption isotherms were employed to give an insight into the adsorption mechanism. The experimental data revealed that first order kinetics was followed during the adsorption of heavy metals onto modified bentonite. Maximum percentage removal of Cr(VI) and Mn(VII) was 80 and 55.5 respectively. Thus locally available bentonite may be utilised as a low cost and eco-friendly alternative of heavy metal removal. [ABSTRACT FROM AUTHOR]

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This study aims to evaluate how the operational procedure adopted for pellet placement and the exposure to subsurface conditions influence the mechanical integrity of bentonite plugs used as barrier elements in the abandonment of petroleum wells. To this end, the plugs were formed by hydrating the pellets directly in water, simulating the onshore procedure, while the offshore plugs were obtained from pellets hydrated in deionized water after immersion in diesel or olefin, which are suggested as displacement fluids. The plugs obtained were tested by compression and adhesion tests. These mechanical tests were also carried out for specimens obtained from plugs exposed to four formulations of synthetic formation waters. The results obtained demonstrated that, in the offshore procedure, the previous contact with olefin may adversely affects the mechanical stability of bentonite plugs, while plugs formed from pellets immersed in diesel presented satisfactory mechanical properties. However, the contact with formation water evidenced that the onshore plug presents superior resistance than the offshore plug previously immersed in diesel. The highly successful performance of the onshore plug was attested by the maintenance of the compressive strength, which exhibited a maximum reduction of 13%, even after exposure to the most saline formation waters. [ABSTRACT FROM AUTHOR]

Composite dielectric materials with different dielectric characteristics are crucial for energy storage devices. In this study, a composite material of 5 wt.% metal (M)/bentonite (Bento) (M = Cd, Cu, Fe, or Zn) was synthesized using a wet impregnation technique to examine the effect of metal incorporation in bentonite. X-ray diffraction, scanning electron microscopy, energy-dispersive x-ray analysis, and impedance analysis were carried out to investigate the structural, morphological, electrical, and dielectric properties of the samples. A low-frequency dielectric response provided evidence of dielectric relaxation, which was associated with local charge polarizations occurring at the grain (or particle) site. A reduction in the dielectric constant was observed in metal-doped composites, attributed to the variation in grain size and the resulting change in the dipole number per unit volume generated by doping. Interestingly, the AC conductivity dispersion decreased for dopants with a larger ionic radius, in line with qualitative expectations. Tight-binding calculations demonstrated that the changes in binding energy, hardness, and the positioning of the highest occupied molecular orbital and lowest unoccupied molecular orbital of Bento were responsible for the differences in dielectric properties resulting from the incorporation of different metals into Bento. Thus, our results demonstrate the successful metal doping-induced tunability of the dielectric and structural properties of Bento, with significant implications for its use as supercapacitor (optimal dopant is Fe, as it induces larger permittivity), and hence its polarizability. The lowest permittivity was achieved for Cd doping, suggesting its potential use for insulator applications. [ABSTRACT FROM AUTHOR]

As industrial production increases worldwide, so does the demand for fuels. The transport of fuels from the point of production to the end user poses a risk of environmental pollution, both during transport and during combustion in internal combustion engines. The soil is a part of the environment which is particularly sensitive to contamination by petroleum substances. For this reason, research has been carried out into the possibility of reducing the impact of petrol on the content of heavy metals in the soil using various materials, both mineral (bentonite, calcium oxide) and organic (compost). These played an important role in the in situ remediation of contaminated soils. Petrol contamination increased the content of some heavy metals (Pb, Cd, or Ni), while it decreased the content of other metals (Cr, Zn, Co, and Cu) in the soil. The materials used in this study significantly altered the levels of heavy metals in the soil. The strength of the effect varied and the direction of the effect depended on the element. Bentonite was the most effective, while calcium oxide and especially compost were less effective. The most beneficial (limiting) effect of calcium oxide was shown on the soil content of cadmium, cobalt, and chromium, while the bentonite effects were on the content of chromium. The application of the abovementioned materials seems to be effective in reducing low level soil contamination by petrol. [ABSTRACT FROM AUTHOR]

AbstractBentonite-gelatin (BT-Ge) and bentonite-sucrose (BT-Su) composites were fabricated using a simple solution mixing method and employed as adsorbents for extracting dyes from aqueous solutions. The structural characteristics of the fabricated composite materials were elucidated using x-ray diffraction, Fourier transform infrared (FTIR) spectroscopy, and thermogravimetric analysis (TGA). The adjustable adsorption capabilities of the developed adsorbents toward methyl red (MR) and methylene blue (MB), representing anionic and cationic dyes, respectively, were examined by varying the mass ratio of bentonite to gelatin and sucrose. The impact of contact time, adsorbent dosage, and pH on the adsorption process of MR and MB onto BT-Ge and BT-Su was investigated. Kinetic data fitting indicated a good agreement with the pseudo-second-order model, with equilibrium typically achieved within 30 min, resulting in 99.69 ± 0.550, 99.56 ± 0.344, 99.90 ± 0.488% removal of MB with BT, BT-Su, and BT-Ge, respectively and 99.50 ± 0.854, 99.50 ± 0.658, and 99.57%±0.501% of MR with BT, BT-Su, and BT-Ge, respectively from the aqueous solutions. Equilibrium data were analyzed using Langmuir and Freundlich isotherm models, with the Langmuir model showing the best fit and indicating a maximum adsorption capacity of 666.66 mg g−1 of MR and 285.71 mg g−1 of MB at 25 °C. These findings underscore the remarkable efficacy of BT-Ge and BT-Su composites in eliminating dyes from wastewater, particularly colored effluents. [ABSTRACT FROM AUTHOR]

In this study, the effect of high‐power bath and horn ultrasound at different powers on specific surface area (SBET), total pore volume (Vtotal), and average pore volume (Dave) of bleaching clay was examined. After subjecting the bleaching clay to ultrasonication treatment, the SBET values demonstrated an escalation from 31.4 ± 2.7 m2 g−1 to 59.8 ± 3.1 m2 g−1 for HU200BC, 143.8 ± 3.9 m2 g−1 for HU400BC, 54.4 ± 3.6 m2 g−1 for BU400BC, and 137.5 ± 2.8 m2 g−1 for BU800BC. The mean pore diameter (Dave) declined from 29.7 ± 0.14 nm in bleaching clay to 11.3 ± 0.13 nm in HU200BC, 8.3 ± 0.12 nm in HU400BC, 16.7 ± 0.14 nm in BU400BC, and 9.6 ± 0.12 nm in BU800BC. Therefore, horn ultrasound‐treated bleaching clay significantly increased SBET and Vtotal, indicating improved adsorption capacity. Moreover, to establish the relationship between bleaching parameters, seven multi‐output ML regression models of Feedforward Neural Network (FNN), Random Forest (RF), Support Vector Regression (SVR), Multi‐Task Lasso, Ridge regression, Extreme Gradient Boosting (XGBoost), and Gradient Boosting are used, and compared with response surface methodology (RSM). ML has revolutionized the understanding of complex relationships between ultrasonic parameters, oil color, and pigment degradation, providing insights into how various factors such as temperature, ultrasonic power, and time can influence the bleaching process, ultimately enhancing the efficiency and precision of the treatment. The XGBoost model showed outstanding performance in predicting the target variables with a high R2‐train up to 1, R2‐test up to .983, and a minimum mean absolute error (MAE) of 0.498. The lower error between the predicted and experimental values implies the superiority of the XGBoost model to predict outcomes rather than RSM. It represents the suitability of bath ultrasound as a mild condition for low‐pigmented oil bleaching. Finally, the Bayesian optimization method in conjunction with XGBoost was used to optimize the amount of bleaching clay and energy consumption, and its performance was compared with RSM. It was observed that the consumption of bleaching clay was reduced by approximately 60% for sunflower oil and 30%–35% for soybean oil. [ABSTRACT FROM AUTHOR]

Soil-bentonite (S-B) barriers have been widely used for heavy metal pollution containment. This study conducted batch adsorption tests and diffusion-through tests to evaluate how ionic strength and bentonite ratio influence the migration of Cr(VI) in natural clay-bentonite mixtures. The test results indicated that the adsorption of Cr(VI) exhibited an obvious anion adsorption effect, the pH of the soil mixture increased with the addition of bentonite, resulting in a decrease in the positive surface charge. This change led to a decrease in Cr(VI) adsorption capacity, from 775.19 mg/kg for pure clay to 378 mg/kg for mixture samples with excessive bentonite. Furthermore, as the ionic strength increases from 0 to 0.1 M, the Cr(VI) adsorption capacity increases slightly due to the weakening of electrostatic repulsion on the clay particle surface, but the effective diffusion coefficient (De) increases by 21.97%. The compression of the diffusion double layer (DDL) under high ionic strength conditions enlarges the diffusion path and enhances the migration of Cr(VI) through the pore flow paths. Moreover, hydrated bentonite effectively fills the interaggregate pores of natural clay, thus creating narrower and more tortuous flow paths. However, excessive bentonite increases the pH value and pore volume, resulting in changes to the soil microstructure and disrupting the continuous skeleton of natural clay, which is unfavorable for Cr(VI) containment. Based on the study of the Cr(VI) contaminated site, a bentonite ratio of 2:10 is recommended for optimal natural performance of the natural clay-bentonite barrier. [ABSTRACT FROM AUTHOR]

Y-type molecular sieve was synthesized hydrothermally using bentonite as the raw material. The study investigated the optimal synthesis conditions and the impact of metal impurities in bentonite on Y-type molecular sieve. Y-1 molecular sieve (synthesized from purified bentonite) has higher crystallinity, stronger acidity, and larger specific surface area, pore size, and pore volume than Y-2 molecular sieve (synthesized from the original bentonite). The elimination of metal impurities from bentonite is advantageous for synthesizing Y-type molecular sieve, as it can significantly enhance its physical properties and structure. HY molecular sieves were prepared by modifying Y-1 and Y-2 through ammonium exchange and were used as catalysts for the hydrocatalytic cracking of shale oil fractions > 350 °C. The findings indicate that the HY-1 catalyst exhibits superior catalytic cracking performance compared to the HY-2 catalyst. The catalyst's performance is comparable to that of commercial Y-type molecular sieve catalyst. Under the conditions of a solid–liquid ratio of 1 g:20 g, an initial hydrogen pressure of 4 MPa, a reaction time of 50 min, and a reaction temperature of 370 °C, the gasoline yield is 63.38%, heavy oil content is only 3.78%, and coke yield is 0.93%. [ABSTRACT FROM AUTHOR]

A sodium bentonite product (nanoclay) was added to a polyhydroxybutyrate/ethyl cellulose (PHB/EC) blend coating agent, and the impact of the nanoclay content on the properties of the coated paper was investigated. The organically treated nanoclay exhibited enhanced compatibility with the PHB/EC blend, ensuring uniform dispersion within the coating layer and improving the barrier properties of the coated paper. The mechanical properties of the PHB/EC blend-coated paper with nanoclay demonstrated ductile behavior, reducing the tensile strength and increasing the elongation. However, at higher nanoclay loadings, specifically up to 25%, aggregation among nanoclay particles occurred. This hindered the enhancement of barrier properties, thereby decreasing the degree of elongation. Incorporating nanoclay as a filler in the PHB/EC blend at suitable levels showed potential for further enhancing the barrier properties and ensuring economic feasibility in the production of packaging paper. [ABSTRACT FROM AUTHOR]

Toxic secondary metabolites of some fungi (mainly representatives of Alternaria, Aspergillus, Fusarium and Penicillium genera) may contaminate agricultural products, representing serious health hazards to both humans and animals. Along with this, the economic losses due to the mycotoxins' presence in feed production, including crop and animal feedstuff processing and distribution, motivated the plentiful research of detoxification strategies. Feed supplementation with mineral adsorbents (zeolites, hydrated sodium calcium aluminosilicate (HSCAS), bentonites, etc.) is the most prominent approach widely applied. Besides these, other products for mycotoxin level reduction based on the constituents of the yeast cell wall or Lactobacilli are often used. Recently, many investigations are directed toward plant-derived products that can efficiently adsorb mycotoxins in their native (biosorbents) or modified forms (e.g. activated carbon, biochar etc.). These renewable, easily accessible and readily prepared sorbents are economically viable and safe alternatives for mycotoxin decontamination of feed resources. Organic polymers (chitosan, cellulose, etc.) as well as synthetic polymers, such as polyvinyl pyrrolidine, also might reduce mycotoxins' level in feed. Besides these conventional methods, new research trends are nanotechnologies, the promising, effective, low-cost way for mycotoxins' removal. This overview systematically summarizes information on binding agents of different origins for the reduction of mycotoxins' levels in feed. Furthermore, the knowledge of potential applications of binding agents in the feed industry is also reviewed and discussed. [ABSTRACT FROM AUTHOR]

In this study, a series of suction-control oedometer tests were conducted on unsaturated and saturated MX80 bentonite pellet/powder mixtures. The mixture samples were imposed with various suctions from 0 to 113 MPa under a low vertical stress (0.1 MPa). Then, the mixture samples were loaded in steps with controlled suction until reaching three different target stresses σv (0.1, 3.2, and 12.8 MPa) and instantaneously unloaded. The microstructure of unloaded samples was observed with mercury intrusion porosimetry (MIP) and microcomputed tomography (μCT), together with the determination of suction, water content, void ratio, and saturation degree. Results showed that the water-retention behavior of bentonite pellet/powder mixture was rather characterized by pellets instead of powder. Due to the stress release, the measured suction after unloading sme was larger than the imposed suction sim. The suction difference Δs between sme and sim depended on both suction and load. Under a given σv , the suction effect was characterized by an increase of Δs when sim decreased from 113 to 4.2 MPa, but by a noticeable decrease of Δs when sim further decreased to zero. This was found to be related to the changes of the slopes of soil-water retention curves (SWRCs): the slope was decreasing with suction increases after 4.2 MPa suction, but was increasing with suction increases before 4.2 MPa suction. As far as the stress effect was concerned, a larger Δs was identified at a higher σv for a given sim. The narrowing difference between Δs and the reduction of mean stress of pellet Δppellet with increasing load was because of the decrease of larger pores due to loading. The total mixture void ratio eTmixture was highly dependent on suction and vertical stress, whereas the total pellet void ratio eTpellet was only dependent on suction in the stress range considered. [ABSTRACT FROM AUTHOR]

This paper aims to study the crystallization kinetics of local bentonite taken from the Maghnia region of Algeria after conducting the toasting process to powder with different temperature degrees 200, 400, 500, 700, 800, 900, 1000°C and 1100°C. The material was examined by differential thermal analysis (DTA) at different heating rates (10–50°C/min), and X ray diffraction (XRD). We used also Infrared Spectroscopy to detect the vibrations characteristic of the chemical bonds and to analyze the molecules forming the material. Scanning electron Microscopy (SEM) has been used to investigate the bentonite microstructure revealing granules shape and distribution. We have applied Non-isothermal crystallization kinetic methods to study the mechanism of crystallization in the bentonite. After a calcinations process at 200°C and 700°C of the bentonite, X-ray diffraction data showed a decrease in the basal spacing (d001) from 12.72 Å of room temperature to about 11.98 Å and 9.93 Å respectively. We also observed the disappearance of the diffraction peaks represented by the d001 interval, which expresses the montmorillonite phase after calcination of samples at 800°C. The average activation energy has been determined by Kissinger method (221.046 kJ/mol), Ozawa method (225.557 kJ/mol) and Boswell method (229.356 kJ/mol). Growth morphology parameters and the frequency factor for the reaction of the dehydroxylation at different temperatures have been measured. [ABSTRACT FROM AUTHOR]

Co-transport of Cr(VI) with bentonite colloids (Bc) at different flow rate, pH, ion strength (IS), and colloid concentration in heterogeneous sand media was investigated. The results showed that obvious penetration of dissolved Cr(VI) in co-transport occurred at about 0.5PV, which was mainly due to the heterogeneity of the sand column. The maximum dimensionless transport fraction ((Ct/C0)max) of dissolved Cr(VI) was 0.73 in the co-transport (200 mg·L-1 Bc and 2.5 ml min-1), much lower than that in the single transport of Cr(VI) (0.98). The increase of pH promoted the transport of Cr(VI) in co-transport with Bc. Elevated flow rate, ion strength, and Bc concentration reduced Cr(VI) transport. Cr(VI) in the effluent in co-transport with Bc was dominated by dissolved Cr(VI), and a small amount of colloidal Cr(VI) (～4.97%) was observed. The recovery rates of total transported Cr(VI) (dissolved +colloidal) in co-transport with Bc were obviously lower than those in single transport. (Ct/C0)max values of dissolved Cr(VI) in the co-transport with Bc were also lower than those with other colloids, e.g. kaolin colloid, montmorillonite colloid, and inorganic soil colloid. Application of bentonite may alleviate the transport risk of Cr(VI) to groundwater. [ABSTRACT FROM AUTHOR]

Coal mining causes surface subsidence, resulting in the loss of phosphorus from the soil surface and affecting crop growth. To provide a basis for the reclamation of soils in coal mining subsidence areas, using the Suntuan mine area in Huaibei City as an example, indoor soil cultivation experiments were conducted to investigate the effects of applying different types of phosphate rock powders (mechanically activated and nonmechanically activated), active minerals (zeolite, kaolin, bentonite) and phosphorus solubilizing microorganisms (Pseudomonas fluorescens, Aspergillus niger) on soil pH, available phosphorous content, and the conversion of soil phosphorus fractions. The results showed that the combined action of phosphate rock powder and phosphorus solubilizing bacteria could significantly improve the soil acidic environment. The application of phosphate rock powder, active minerals, and phosphorus solubilizing microorganisms can promote the release of available phosphorous in soil, and Aspergillus niger has a better effect than Pseudomonas fluorescens. Soil content of H2O-P, NaOH-Pi, NaHCO3-Pi, and HCl-P increased, NaOH-Po decreased, and some treatment groups had reduced Residual-P content. Together, phosphate rock powders, active minerals, and phosphorus solubilizing microorganisms can mitigate soil acidification, promote soil phosphorus release, result in the transformation of soil phosphorus fractions, and improve phosphate fertilizer utilization. [ABSTRACT FROM AUTHOR]

The synthesis of multifunctional composites still relies on the use of conventional methods. However, these methods are expensive, time consuming and require high volumes of reducing agents which are often toxic. In this study, composites of bentonite-supported silver nanoparticles were prepared comparatively by the conventional heating method and the rapid microwave method; and their antibacterial activity was investigated against Escherichia coli and Staphylococcus aureus. The crystalline nature of the composites was evaluated by X-ray diffraction (XRD), while transmission electron microscope (TEM) coupled with energy-dispersive spectroscope was used for morphology and elemental analysis, respectively. Surface area and pore size analysis of the composites were conducted by the Brunauer, Emmett and Teller analyzer. TEM images revealed successful synthesis of the composites with a better dispersion of the nanoparticles achieved through microwave, where nanoparticle sizes were 6–38 nm and 9–56 nm by the conventional method. It is worth noting that the composites were prepared in less than 30 min using microwave as compared to 2 h of the conventional method. The XRD spectra confirmed the formation of silver and not any other impurities of the metal. These results revealed that, although the two methods are comparable, microwave method is efficient and time saving and can, therefore, synthesize composites with well-dispersed and narrow distributed nanoparticles. The antibacterial results demonstrated that the prepared composites are effective in the inactivation of various bacteria. These composites could be applied in water treatment, wound dressing, packaging, etc. [ABSTRACT FROM AUTHOR]

Photocatalytic degradation of benzene is a viable and environmentally friendly method with significant economic advantages. In this study, a composite photocatalyst consisting of TiO2 and Fe3O4 supported by bentonite was synthesized for benzene degradation. The objective was to assess the impact of critical parameters in both batch and continuous systems. The results showed that in batch system, the effects of initial benzene concentration and pH were explored, showing optimal degradation at an initial concentration of 400 ppm and pH 5. Under these conditions, an impressive % removal value of 95.334 % was achieved. Meanwhile, continuous system analysis showed a negative correlation between feed flow rate and % removal, with the most effective degradation occurring at a flow rate of 15 mL/min. The study also delivered into the kinetics of benzene degradation in batch system, obtaining a first-order reaction based on Langmuir-Hinshelwood model with a reaction rate constant (kr) of 85.68175 mg/(L.min) and an adsorption rate constant (K) of 0.0003002 L/mg. The adsorption model was observed to follow the Langmuir model. These results contributed to the optimization of photocatalytic benzene degradation processes, offering insights into the critical factors affecting efficiency in both batch and continuous systems. The established optimum conditions and kinetic parameters provided a foundation for future advancements in the design and application of composite photocatalysts for benzene remediation. [ABSTRACT FROM AUTHOR]

In response to the poor removal effect of tetracycline from wastewater by natural bentonite (Bt), BS-12 was used to modify Bt and prepare BS-12 modified bentonite (BS-Bt) adsorption material, studied the adsorption performance of BS-Bt and Bt on tetracycline in wastewater, and the dosage of adsorbent pH and ionic concentrations were discussed. The results show that the adsorption capacity of Bt and BS-Bt for tetracycline increases with the decrease of adsorbent addition amount; with the increase of pH;with the Ca2+ concentrations increasing, the adsorption capacity present slowly decreasing trend. The adsorption process of tetracycline by Bt and BS-Bt could be completed rapid adsorption within 1 h, and reached adsorption equilibrium within4 h, it conforms to the quasi-second order dynamic equatioti (R² >0. 996) . The Freundlich model has good nonlinear fitting ability for adsorption data, and adsorption isotherms are "L-type". The adsorption capacity of organically-modified bentonite to tetracycline was significantly higher than that of bentonite, which made it a potential adsorbent for tetracycline wastewater treatment. [ABSTRACT FROM AUTHOR]