The structural stability of barrier layers is critical for the long-term effectiveness of landfill remediation projects, although leachate pumping and organic contamination can cause structural degradation, reduce remediation performance, and increase the risk of pollutant release. The objectives of this study were to determine the consolidation–rebound mechanisms of sand–bentonite mixtures through standardized tests and to analyze deformation under diesel contamination using multi-scale approaches, including pore-structure characterization, particle-size distribution, cation exchange capacity, and oil-blocking effects. The results revealed that uncontaminated soil (0.0 wt.% diesel) exhibited non-linear compression behavior, with an initial decrease and a subsequent increase with increasing sand content; when the consolidation pressure exceeded 400 kPa, the compression rate decreased markedly. The compression deformation of the contaminated soil increased and was positively correlated with the sand and diesel contents, with accelerated deformation at >4.0 wt.% diesel. The rebound capacity decreased under combined sand–diesel effects. Microstructural analysis indicated that initial compression was controlled by inter-aggregate pores, whereas mid- to late-stage compression was influenced by intra-aggregate pore evolution and particle breakage. Increased diesel content shifted aggregate breakage from single/secondary to tertiary patterns, altering later compression behavior. Coupled hydration reduction and enhanced oil-blocking suppressed rebound significantly, worsening with increasing diesel content. Technical–economic analysis revealed that pure bentonite (0% sand) was optimal under uncontaminated conditions and that a 10% sand mixture was best under contaminated conditions. The sand–bentonite barrier exhibited amplified consolidation–rebound deformation and reduced stability with increasing sand and diesel contents, providing a theoretical basis for long-term landfill remediation assessment.

Improving the thermal and rheological limitations of traditional natural hydrogels remains a key challenge for their medical use. Inorganic and organic elements were combined synergistically to develop natural hydrogels, and subsequently subjected to comprehensive thermal and rheological analysis for potential applications in physical medical treatments. The primary objective of this study was to optimize the technological, biopharmaceutical, and therapeutic properties of these innovative hydrogels, constituted by an inorganic framework of clay particles entrapping organic components from peat extracts. The hydrogels underwent thorough mineralogical and chemical characterization, confirming the pharmaceutical-grade quality of the clay component, which was predominantly composed of montmorillonite and saponite. Rheological evaluations revealed non-Newtonian viscoplastic behavior, with viscosity and thixotropy increasing significantly with higher clay concentrations and prolonged swelling durations. Thermal analyses demonstrated that the hydrogels possess adequate heat-transfer capabilities, ensuring effective maintenance of skin temperature during therapeutic application. Elemental analysis and cation exchange capacity determinations highlighted the substantial water retention and ion exchange properties of the hydrogels, contributing to their stability and functional performance. The integration of organic and inorganic constituents enhanced synergistically the mechanical strength, thermal stability, and therapeutic efficacy of the hydrogels. These advancements position the formulated hydrogels as promising candidates for innovative applications in physical medical treatments, offering enhanced mechanical and thermal properties essential for effective therapeutic outcomes.

One of the challenges in measuring the adsorption of metal cations is that they may form metal hydroxide compounds at certain pH ranges. This becomes problematic when adsorption is quantified in terms of measuring a decrease in metal ions in solution, because metal hydroxy complexes are removed from solution through precipitation, leading to erroneously high determinations of adsorption. Within this context, the present study aimed to analyze the pH-dependent adsorption behavior of Ni2+ ions onto sepiolite, a naturally occurring magnesium silicate clay mineral, while simultaneously accounting for the precipitation of nickel compounds during the process. For this purpose, zeta potential, ion exchange capacity, and the adsorption behavior of 2.5×10–3 mol L–1 nickel (II) sulfate hexahydrate onto relatively high-quality sepiolite were investigated. Kinetic studies and thermodynamic assessments were delineated to enhance the understanding of adsorption isotherms, both for future research and practical applications in environmental remediation. The results showed that the adsorption of Ni2+ ions onto sepiolite before the onset of precipitation is governed by an ion exchange process involving the release of Mg2+ ions from the sepiolite matrix and the uptake of Ni2+ ions from the solution. Above the threshold of pH ~8 where Ni-hydroxide complexes begin to form, ~97% of nickel ions were present in the forms of NiOH+, Ni(OH)2, and Ni(OH)3–. Isotherms for total Ni2+ removal were constructed to distinguish true adsorption from precipitation phenomena. The calculated and experimental values for true adsorption were found to be in good agreement.

Organomontmorillonite-type (O-Mnt) antibacterial agents are less susceptible to development of resistance by bacteria. The aim of the present study was to test the effects of O-Mnt samples, which were reported to be effective against Staphlococcus aureus and Streptococcus mutans in previous studies and to act as a scavenger for opportunistic pathogenic microorganisms, Actinomyces viscosus and Bacteroides fragilis, which cause severe infections such as periodontal diseases, endocarditis, and lung infections. O-Mnt samples with single and mixed surfactant layers, namely benzethonium montmorillonite (Mnt-BZT) and cetylpyridinium and N-lauroyl sarcosinate montmorillonite (Mnt-CP-SR), were subjected to X-ray diffraction, thermogravimetric analysis, attenuated total reflectance-fourier transform infrared spectroscopy (ATR-FTIR) and zeta potential analyses to determine some key structural properties. Within the scope of the present study, detailed X-ray photoelectron spectroscopy (XPS) analyses were performed to elucidate the external surface structures, which are important in explaining their antibacterial properties. There have been few studies on XPS analysis in terms of types of surfactants used in O-Mnt preparation. These analyses made it possible to estimate the interaction between the surfactants on the external surface and the bacterial cell wall leading to lysis. A. viscosus, a facultative anaerobe, and B. fragilis, a strict anaerobe, required specific culture conditions, and their antibacterial susceptibility testing was conducted with caution due to challenges in isolation and antimicrobial resistance. Antibacterial susceptibility tests including the agar well diffusion test, minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) determinations and time-kill assay showed that both OMnt samples were effective against the bacteria used. The XPS analyses of the exterior surface structure of O-Mnt revealed that contact killing was the mechanism of antibacterial effect. In vitro cytotoxicity and in vivo animal studies indicated that both O-Mnt samples can be used safely as antibacterial agents in oral and topical applications.

Aflatoxins (AFs) are contaminants of several agricultural crops, and aflatoxin B1 (AFB1) is the most toxic AF and a known carcinogen to humans and animals. A practical solution for decontamination of animal feed contaminated with AFB1 is to use bentonite, a natural raw material consisting primarily of the mineral montmorillonite (dioctahedral 2:1 layer aluminosilicate of the smectite group). The aims of this research were to compare mineralogical, structural, chemical, and physico-chemical characteristics of three bentonites from the Balkan region (Beretnica clay from Serbia (B-Clay), Yellow clay (Y-Clay) and Gray clay (G-Clay) from Bosnia) with the characteristics of a commercial pharmaceutical-grade bentonite (P-Clay), and to study the behavior of the bentonites in phosphate buffer at pH 3 and 7 with and without AFB1. AFB1 adsorption by bentonites followed non-linear isotherms with maximum amounts adsorbed from 75.43 mg g–1 at pH 3 and 62.91 mg g–1 at pH 7 for the P-Clay to 100.25 mg g–1 at pH 3 and 78.58 mg g–1 at pH 7 for the B-Clay. The Ca-bentonites (B-Clay-cis-vacant, 83% montmorillonite; Y-Clay-cis/trans-vacant, 98% montmorillonite; and G-Clay-trans-vacant, 88% montmorillonite) were efficient adsorbents of AFB1, with the greater adsorption observed at pH 3. The P-Clay (Na/Ca bentonite, cis-vacant, 63% montmorillonite), exhibited the lowest AFB1 adsorption at both pH values. The behavior of bentonites in buffers, in the presence of AFB1, indicated that ion exchange and AFB1 adsorption by montmorillonite occurred simultaneously. Cations with larger hydrated radii (Mg2+ and Ca2+) represented the primary active sites for AFB1 adsorption. The position of OH– groups in cis-montmorillonites at the same side of the octahedral site enhanced AFB1 adsorption, making them more available for protonation of edge sites and subsequent interaction with AFB1. Specific characteristics of the montmorillonite in bentonites play an important role in AFB1 adsorption, although the buffer composition also affects the adsorption process significantly.

This article studies the geological structure, mineralogical composition, genesis, and sorption properties of Khonguruu zeolite deposit (Republic of Sakha, Russia). Although it is one of the largest developed deposits in Russia, detailed studies of the mineral composition and physicochemical properties have not been conducted previously, which limits its industrial potential. Zeolites were studied with X-ray diffraction (XRD), scanning electron microscopy (SEM), differential thermal analysis (DTA), X-ray fluorescence spectrometry (XRF), Fourier transform infrared spectroscopy (FTIR), Brunauer–Emmett–Teller (BET) and cation exchange capacity (CEC) analyses. Experiments on the sorption of radioactive cesium were also carried out. Zeolites formed four beds with an average content of 50–85%. The main focus of this study is on the detailed investigation of its mineral composition. These data, together with the analyses of ion-exchange complexes and color, provided an opportunity to distinguish between different types of zeolites. The zeolite minerals are represented by heulandite-1, heulandite-2 and, to a lesser extent, clinoptilolite. For the first time, a significant presence of amorphous silica was demonstrated in zeolite samples and used for correction of the crystallochemical formula of zeolites. On the basis of exchangeable cations composition, two main types of zeolites were found at the deposit: alkaline and alkaline-earth. The CEC of the zeolites ranged from 139 to 214 cmolc kg–1 and high 137Cs sorption. The zeolites have a volcanogenic-sedimentary genesis and were formed from ash material of basic and acidic composition in coastal sea waters with alternating conditions of low and high salinity. Based on the data obtained, it can be concluded that the alkaline raw material can be used as a sorbent for wastewater treatment.

Smectite- and zeolite-dominated assemblages occur at different depths within the same volcanic tuff sequence at the study site, indicating variability in post-depositional alteration conditions. The present study investigated the geological and environmental factors associated with the vertical mineralogical differences using outcrop and core samples from Pohang, South Korea. Mineralogical, geochemical, thermal, spectroscopic, and microbial analyses were conducted on representative samples. The outcrop samples contain Ca-smectite, cristobalite, and amorphous aluminosilicates, whereas the core samples contain zeolite (clinoptilolite and mordenite), quartz, and feldspar. (Na,Ca)-smectite occurs only at specific depths within the core. Major- and trace-element geochemistry indicates that the outcrop and core samples were derived from rhyolitic and andesitic precursors, respectively. Chondrite-normalized rare earth element patterns show no evidence of hydrothermal enrichment or depletion, suggesting diagenesis as the dominant alteration process. Bacterial community compositions, used as environmental indicators, indicate contrasting formation environments: the outcrop samples represent anaerobic, freshwater conditions, whereas the core samples reflect aerobic and saline conditions. Mössbauer spectra independently support these redox differences, showing structurally bound Fe within smectite in the outcrop sample and hematite-magnetite assemblages in the core samples. These results indicate that variations in precursor composition, salinity, and redox conditions were closely associated with the development of contrasting smectite- and zeolite-bearing assemblages within the same volcanic sequence.