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As a type of atmospheric particulates, it is important to understand the characteristics of the atmospheric microbial-mineral aerosol. This paper focuses on the montmorillonite/bacteria complex, which is prepared by combining montmorillonite and three common strains of bacteria (Escherichia coli, Staphylococcus aureus, and Bacillus pumilus) in the solution system. The particle size, morphology, surface potential, and surface group characteristics of the extracted montmorillonite/bacteria complex were analyzed by modern analysis and testing technology. Results demonstrate that both montmorillonite and three common strains of bacteria can form the mineral/bacteria complex. The scanning electron microscopy results showed that S. aureus adheres to the montmorillonite in a multi-layered manner, while E. coli and B. pumilus cement the montmorillonite particles to form the complex. Additionally, the presence of the globular bacteria outnumbered the rod-shaped bacteria. The particle size of the montmorillonite/bacteria complex increased, ranging from 1.53 to 4.71 times larger than that of the original particles. The matching trend results suggest that the formation of the montmorillonite/bacteria complex does not follow a one-to-one relationship. The surface potential of the complex was negatively charged within a pH range of 2~11, without an isoelectric point. The potential value of the complex tends toward that of montmorillonite, indicating that non-electrostatic interactions primarily govern the complex formation. The most prominent FTIR spectra of the montmorillonite/bacteria complex corresponded to the peaks of montmorillonite, with additional peaks representing protein and polysaccharide from the bacteria. These signify the adherence of bacteria to the surface of the montmorillonite. The β-sheet/α-helix ratio of bacteria in the montmorillonite/bacteria complex increased indicating that the hydrogen bonding plays a dominant role in the complex formation.

In this study, the removal of ciprofloxacin hydrochloride (a fluoroquinolone antibiotic) by using various effective adsorbents such as activated carbon, montmorillonite, modified montmorillonite (commercial name Cloisite 20A), and alumina was investigated. Adsorption experiments were performed to determine and compare the adsorption capacities of these adsorbents. The adsorption capacities of adsorbents were examined at different initial concentrations of ciprofloxacin hydrochloride. Activated carbon was found to be having the best adsorption capacity for the removal of ciprofloxacin hydrochloride. For the solution having an initial ciprofloxacin hydrochloride concentration of 4 ppm, the adsorption capacities of adsorbents were obtained as 1.86 mg g−1 for activated carbon, 1.67 mg g−1 for modified montmorillonite, 1.15 mg g−1 for alumina, and 0.60 mg g−1 for montmorillonite. And also, about 92% of the ciprofloxacin hydrochloride was removed from the water using the activated carbon. In addition, Langmuir, Freundlich, and Temkin isotherm models were employed to express the adsorption process. For all adsorbents, Freundlich isotherm model provided best fitting to the experimental data because of very high values of R2 (> 0.99). Kinetic models of pseudo-first order, pseudo-second order, Elovich, and Weber-Morris intraparticle diffusion model were utilized to evaluate the experimental adsorption data. Adsorption kinetics data were well represented by pseudo-second order kinetic model with values of R2 (> 0.999).

Metal cations are often used to regulate montmorillonite, but the mechanism is still unclear. In this paper, the regulation of different cations in montmorillonite was studied, and it was found that the regulation of different cations had significant effects on the structure of montmorillonite. Firstly, the viscosity is negatively correlated with particle size, and the order of particle size is trivalent > divalent > monovalent cation. Secondly, the swelling capacity is positively correlated with the absolute value of zeta potential, and the order of the zeta potential is monovalent > trivalent > divalent cation. Thirdly, the smaller hydrated ion radius and static electricity of monovalent cations significantly reduce the layer spacing. Meanwhile, isomorphism displacement results in a significant increase in the proportion of cis-vacant configuration due to changing the electronegativity of the octahedron. The comprehensive performance is that the particle size is significantly reduced and the absolute value of zeta potential is significantly increased. It is easy to peel off and expand in water to form a uniform and stable colloidal substance, which has the best gel performance. The research results can provide theoretical support for the regulation of montmorillonite structure and gel properties by different valence metal cations.

The toxicity of two pesticides, diazinon (DAZ) and atrazine (ATR), before and after montmorillonite-catalyzed ozonation was comparatively investigated on the duckweed Lemna minor. The results allowed demonstrating the role of clay-containing media in the evolution in time of pesticide negative impact on L. minor plants. Pesticides conversion exceeded 94% after 30 min of ozonation in the presence of both Na[sup.+] and Fe[sup.2+] exchanged montmorillonites. Toxicity testing using L. minor permitted us to evaluate the change in pesticide ecotoxicity. The plant growth inhibition involved excessive oxidative stress depending on the pesticide concentration, molecular structure, and degradation degree. Pesticide adsorption and/or conversion by ozonation on clay surfaces significantly reduced the toxicity towards L. minor plants, more particularly in the presence of Fe(II)-exchanged montmorillonite. The results showed a strong correlation between the pesticide toxicity towards L. minor and the level of reactive oxygen species, which was found to depend on the catalytic activity of the clay minerals, pesticide exposure time to ozone, and formation of harmful derivatives. These findings open promising prospects for developing a method to monitor pesticide ecotoxicity according to clay-containing host-media and exposure time to ambient factors.

Tight oil reservoirs are widely recognized as a critical successor in global unconventional energy development and are generally characterized by distinct geological features, including fine pore throats, pronounced heterogeneity, and a high concentration of clay minerals (e.g., montmorillonite and mixed-layer illite/smectite). Severe hydration, swelling, and fines migration are readily induced during water injection or conventional water-based fluid operations, thereby resulting in irreversible impairment of reservoir permeability. Despite the excellent injectivity and capacity for viscosity reduction associated with CO[sub.2] flooding, sweep efficiency is severely compromised by viscous fingering and gas channeling, which are induced by the inherent low viscosity of the gas. While CO[sub.2] foam technology is widely acknowledged as a pivotal solution for addressing mobility control challenges, its implementation is hindered by a primary technical bottleneck: the incompatibility between traditional water-based foam systems and strongly water-sensitive reservoirs. A dual challenge comprising water injectivity constraints and gas channeling is presented by strongly water-sensitive tight oil reservoirs. To address these impediments, three emerging low-damage CO[sub.2] foam systems are critically evaluated in this review. First, the synergistic mechanisms of novel quaternary ammonium salts and polymers in inhibiting clay hydration and enhancing foam stability within modified water-based systems are elucidated. Next, the physical isolation strategy of substituting the water phase with a non-aqueous phase (oil/organic solvent) in organic emulsion systems is analyzed, highlighting advantages in wettability alteration and the mitigation of water blocking. Finally, the prospect of waterless operations using CO[sub.2]-soluble foam systems—wherein supercritical CO[sub.2] is utilized as a surfactant carrier to generate foam or viscosify fluids via in situ formation water—is discussed. It is revealed by comparative analysis that: (1) Modified water-based systems are identified as the most economically viable option for reservoirs with moderate water sensitivity, wherein cationic stabilizers are utilized to inhibit hydration; (2) Superior wettability alteration and the elimination of aqueous phase damage are provided by organic emulsion systems, rendering them ideal for ultra-sensitive, high-value reservoirs, despite higher solvent costs; (3) CO[sub.2]-soluble systems are recognized as the future direction for “waterless” flooding, specifically tailored for ultra-tight formations (<0.1 mD) where injectivity is critical. Current challenges, such as surfactant solubility, high-temperature stability, and cost control, are identified through a comparative analysis of these three systems with respect to structure-activity relationships, rheological properties, damage control capabilities, and economic feasibility. What is more, an outlook is provided on the molecular design of future environmentally sustainable, cost-effective CO[sub.2]-philic materials and smart injection strategies. Consequently, theoretical foundations and technical support are established for the efficient exploitation of strongly water-sensitive tight oil reservoirs. By bridging the gap between reservoir damage control and mobility enhancement, this study identifies viable strategies for enhanced oil recovery. Crucially, it supports carbon neutrality and sustainable energy targets via CCUS integration.

In response to the widespread and difficult-to-treat phenomenon of antibiotic pollution by ciprofloxacin hydrochloride, this study has chosen to adopt a simple and efficient adsorption method for its treatment and innovatively proposed a method for preparing biochar/montmorillonite composites through pyrolysis and intercalation methods for adsorption treatment. The study also analyzes factors affecting the adsorption effect as well as the adsorption thermodynamics and kinetics characteristics, aiming to provide new efficient and low-cost technologies and ideas for the treatment of antibiotic wastewater. And the research indicates: a) Compared to single biochar and montmorillonite, the specific surface area of biochar/montmorillonite composites has significantly increased, with C2M1C reaching 246.729 m2.g-1, which is 91% higher than ZBC. The reason is that the composite material’s surface has both the layered structure of montmorillonite and the tubular pore structure of biochar. b) The optimal ratios for preparing composites by pyrolysis and intercalation methods are 1.5:1 and 2:1, respectively, and composites prepared at these ratios exhibit the best adsorption effect for CIP. c) Composite materials are more suitable for CIP adsorption in alkaline environments (with an optimal pH value of 10). d) The adsorption capacity of CIP increases with time, initial concentration, and temperature. e) The adsorption capacity of composite materials for CIP decreases significantly with an increase in the number of cycles. The adsorption amounts of materials R1.5M1D and intercalated composite material C2M1C dropped from 89.457 and 114.782 mg g-1 during the first cycle to 16.237 and 24.353 mg g-1 in the fifth cycle, with decreases of 81% and 78%, respectively.

Heavy metal pollution such as water contamination by Pb, Hg, Cu, Cd and Cr ions is induced by rapid urbanization and industrialization and is a major threat to human health. One of the most efficient processes to clean contaminated water is adsorption. Adsorbents such as clay minerals and modified clays are efficient for the removal of metal ions from wastewater. This manuscript reviews current research in heavy metal adsorption by clay minerals such as halloysite, bentonite, montmorillonite, vermiculite and attapulgite, from 2013 to 2017, and highlights the main adsorption mechanisms. The structure, composition and synthesis of various clay minerals and modified clays are presented.

2-Mercaptobenzothiazole (2-MBT) is a prevalent organic pollutant in the environment that poses significant challenges for complete removal using conventional water treatment methods. In this study, we successfully synthesized Bi.sub.3O.sub.4Br/MMT composites by incorporating the clay mineral montmorillonite (MMT), which effectively addresses the issues of low specific surface area and poor adsorption performance commonly observed in traditional Bi.sub.3O.sub.4Br materials. Furthermore, the aluminum species in MMT facilitate the transfer of photogenerated electrons from Bi.sub.3O.sub.4Br to MMT, thereby inhibiting the recombination of electron-hole pairs and enhancing photocatalytic performance. The photocatalytic properties of the photocatalyst were appraised using 2-MBT as the target contaminant. The Bi.sub.3O.sub.4Br/MMT composites demonstrated a remarkable degradation efficiency of nearly 90% for 2-MBT within just 3 min of visible-light irradiation, surpassing 99% after 7 min, along with exceptional cycling stability and structural integrity. Quenching experiments and electron paramagnetic resonance (EPR) analysis identified superoxide radicals (·O.sub.2.sup.-), holes (h.sup.+), and electrons (e.sup.-) as the primary reactive species driving the photocatalytic degradation of 2-MBT. This work provides a promising strategy for the development of environmentally friendly catalytic systems for the efficient degradation of 2-MBT in water.

A highly resourceful, environmentally benign, and recyclable magnetic montmorillonite composite (MMT/CF) was obtained through a simple one-step hydrothermal method and exhibited excellent Pb (II) removal. The as-synthesized adsorbent was then characterized by XRD, SEM–EDX, FTIR, BET, and TGA-DTA. The operating parameters including adsorbent dosage, initial Pb (II) concentration, solution pH, and time were studied. Also, a comparative approach was formed between response surface methodology (RSM) and artificial neural network (ANN) to optimize and model the removal efficiency of Pb (II) by MMT/CF. The results indicated that the ANN model was more precise and quite trusted optimization tool than RSM in consideration of its higher correlation coefficient ( R 2  = 0.998) and lower prediction errors (RMSE = 0.851 and ADD = 0.505). Langmuir isotherm provided the best fit to the experimental data, and the maximum adsorption capacity was 101.01 mg/g. Additionally, the kinetic studies showed that the pseudo-second-order model fitted well with the experimental data. The magnetic MMT/CF composite possesses high adsorption capacity and is suitable for reuse. Therefore, this study shows that MMT/CF composite can be a potential adsorbent in Pb (II) uptake from aqueous media.

Expansive soil is blamed for many engineering problems such as foundation damages, subgrade heave, and road surface bulking. Lime is one of the most widely utilized materials in the stabilization of expansive soil. However, the stabilization mechanism of lime-treated expansive soil has not been thoroughly studied from the nanoscale level. This paper employed montmorillonite (Mt) and portlandite (Po) to represent expansive soil and the hydration product of lime. Four types of portlandite-montmorillonite (Po-Mt) molecular models with different surface charges and interlayer cations revealed the nanoscale stabilization mechanism of Po-Mt. The results show that volume change of Po-Mt samples is not only related to adsorption energy of Mt, but also controlled by competitive adsorption of Po and interaction between lime and Mt. The interface energy between Po and Mt generated by Ca ions migration from Po to Mt surface plays a most significant role in governing the swelling behavior of Po-Mt by providing strong repulsive force to confine the swelling of Mt layers.