In unsaturated soil mechanics, the liquid bridge force is a significant source of soil cohesion and tensile strength. However, the classical Young-Laplace equation, which neglects the stratified nature of water at the nanoscale, fails to accurately capture the physical and mechanical behaviour of nanoscale liquid bridges. This study utilizes molecular dynamics simulations to investigate the wetting behaviour and mechanical mechanisms of liquid bridges between particles at the nanoscale. The study proposes dividing the liquid bridge force into three components: surface tension, matric suction, and adsorption force, to explain the mechanics of nanoscale liquid bridges more comprehensively. The results demonstrate that water layers within liquid bridges exhibit discrete stratified structures at the nanoscale. Moreover, the mechanical behaviour of liquid bridges is highly dependent on pore water volume and pore spacing. Specifically, the contact angle is positively correlated with the pore spacing, while the liquid bridge force increases with the pore water volume and is inversely proportional to the pore spacing. As the separation distance increases, the liquid bridge force gradually diminishes until rupture occurs. This research expands the applicability of the classical Young-Laplace equation and offers new insights into the mechanical properties of unsaturated soils, particularly clays.

The discharge of heavy metals (HMS) from industrial production has severely damaged the natural environment and human health. To address the challenges posed by heavy metals, a novel almond shell biochar (FeSCTS@nBC) modified with FeS and chitosan (CTS) was prepared. Scanning electron microscopy and X-ray photoelectron spectroscopy observations revealed a uniform distribution of FeS particles on the biochar. Adsorption thermodynamics experiments showed that the maximum adsorbed amounts of cadmium (Cd), lead (Pb), and chromium (Cr (VI) and Cr (III)) in FeS-CTS@nBC were 85.6, 89.63, 94.2, and 75.62 mg/g, respectively. Results of soil incubation experiments indicated that FeS-CTS@nBC had a desirable immobilization effect on heavy metals, decreasing the bioavailability of Cd, Pb, Cr (VI), and Cr (III) by 29.43%, 23.93%, 5.75% and 5.23 %, respectively. Density functional theory (DFT) calculations, revealed that the oxygen-containing functional groups on the biochar exhibited stronger adsorption capacities for heavy metals. Plant potting experiments indicated that the paddy grew well in the soil remediated with FeS-CTS@nBC. The Cd content in the roots and leaves of the paddy after nBCS2 repair was reduced by 28.01 % and 55.73 %, respectively. Overall, this work provides a promising low-cost method with a simple production process for mitigation of heavy metals from water and soil.

Biodegradable mulch film is considered a promising alternative to traditional plastic mulch film. However, biodegradable mulch film-derived microplastics (BMPs) in the environment have been reported as carriers for herbicides. Particularly in agricultural settings, limited attention has been given to the abiotic and biological aging processes of BMPs, as well as the herbicides adsorption mechanisms and associated health risks of BMPs. This study investigated the adsorption behaviors and mechanisms of mesotrione on both virgin and aged polylactic acid (PLA)/poly (butylene adipate-co-terephthalate) (PBAT) BMPs, and further evaluated their bioaccessibilities in gastrointestinal fluids. A variety of physical and chemical methods, including scanning electron microscopy (SEM), fourier transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS), revealed increased roughness, generation of oxygen-containing functional groups, and higher O/C ratios of PLA/ PBAT BMPs after ultraviolet (UV) and microbial aging processes. Both UV aging and microbial aging significantly enhanced the adsorption levels of mesotrione on PLA and PBAT BMPs by approximately two-fold, driven by pore filling, hydrogen bonding, and it-it conjugation. The adsorption capacity of mesotrione on BMPs decreased with the pH from 3.0 to 11.0, which was involved by electrostatic interactions. In addition, salt ionic strength (Na+, Ca2+, Mg2+, Fe3+) generally inhibited the adsorption due to ions competition for adsorption sites. Notably, mesotrione exhibited high bioaccessibility when adsorbed onto BMPs, with aged BMPs exhibiting greater desorption quantities in gastrointestinal fluids compared to virgin BMPs. These findings provide effective insights into the potential health threats posed by BMPs carrying herbicides in the environment and offer applicable guidance for managing and remediating composite pollution involving BMPs and adsorbed contaminants.

Activated coke waste (ACW), a byproduct of industrial desulfurization and denitrification, consists of fine particles ( Na+ > Cl-. Isothermal adsorption analysis revealed that Na+ and Cl- adsorption aligned with the Langmuir model, whereas SO42- adsorption adhered to the Freundlich model. Application of SACW (>= 10 g kg(-1)) effectively improved saline-alkali soil properties by lowering pH and salinity, enhancing soil aggregate stability, and promoting nutrient utilization efficiency. Notably, SACW-treated soils supported maize plants with significantly increased height and biomass (13.94% and 159.28% higher, respectively; P <= 0.05) compared to untreated controls. These benefits stemmed from improved nutrient availability and reduced salt stress-induced plasma membrane damage. These findings validate SACW as a sustainable, functional amendment for reclaiming saline-alkali ecosystems and boosting crop productivity.

Excessive bromine, iodine and dyes can damage soil structure and aquatic ecosystems. Therefore, capturing toxic bromine, iodine and dyes from nuclear fuel waste and organic waste liquid is crucial for protecting the environment and human health. In this study, a tridentate imide acid monomer was synthesized with various functional groups and structures, including carboxyl (-COOH), amide (-CONH), and imide rings, to construct a new type of hyper-crosslinked poly (amide-imide) (PAI1-PAI4). Subsequently, porous carbons (PAI1-900-PAI4900) were prepared, and urea was doped during the secondary carbonization process. The ammonia gas (NH3) and carbon dioxide (CO2) generated from the high-temperature decomposition of urea can be trapped by the porous structure of the carbon-based derivatives, and these gases then react with the carbon in the porous carbon and the N-H/C-H in the amide groups, thus resulting in carbon-based materials (PAI1-U-900-PAI4-U-900) with multiple nitrogen and oxygen Lewis basic sites (C-N/N-O/C--O/-OH) and a moderate porosity. These materials enhanced the interactions between the adsorbent and bromine, iodine, and anionic dyes, and exhibited selective adsorption effects for bromide and Congo red (CR).

The accumulation of allelochemicals in farming land has attracted a great deal of research attention, and biochar has shown positive effects in alleviating allelopathy. This study investigated how oligotrophic biochar application modulated salicylic acid (SA) generation in soybean roots through nutrient and oxidative stress pathways. Biochars were applied to soybean cultivation, with analyses conducted on nutrient adsorption, allelochemical profiles, and plant growth parameters. Results revealed that biochar suppressed benzoic acid (BA) while elevating SA levels, which correlated with the presence of persistent free radicals (PFRs) and nutrient retention. The retention of phosphorus (P) and ammonium (NH4+-N) dominated plant height reduction, surpassing oxidative stress effects linked to PFRs. Multivariate linear regression (MLR) identified P retention as the primary driver of SA generation, linked to adaptive phosphorus solubilization via acid secretion. Conversely, malondialdehyde (MDA) accumulation resulted from lipoxygenasemediated lipid peroxidation under nutrient stress and PFRs-induced oxidative stress. The strong adsorption of P and nitrate (NO3--N) by biochar exacerbated soil oligotrophy, triggering SA overproduction as a stress compensation mechanism. The significant correlation between SA and MDA indicated bidirectional stress signaling, wherein allelochemicals exacerbate oxidative damage while activating defense responses. These findings emphasize the dual role of biochar as both a stress inducer and an allelopathy modulator, highlighting the necessity for optimizing pyrolysis and developing soil-specific strategies to balance agricultural benefits with ecological risks.

Uranyl ions (UO22+) are the form of uranium usually dissolved in water and are radioactive and can cause serious damage to the environment. Adsorption of uranyl ions is a critical method for removing and safely storing radioactive materials that harm the environment. It is also an important tool for combating water and soil contamination, managing nuclear waste and environmental sustainability. Polymer-based composites were developed for this purpose. Polymer-based composites enable the efficient removal of harmful and radioactive uranium compounds from water and soil. Through the incorporation of polymers and fillers (such as zeolite), materials with specific properties capable of adsorbing uranyl ions with high efficiency can be designed. The ratio of the components constituting the composites can be adjusted to optimize the adsorption capacity, as well as the chemical and thermal behaviors. Two composites were created: P(MA-Z50), consisting of ethylene glycol dimethacrylate (EGDM), methacrylic acid (MA), and zeolite, and P(MA-Z75), which contained a higher amount of zeolite. These composites were synthesized at room temperature and analyzed using various techniques such as Fourier transform infrared (FTIR), thermal gravimetric analysis (TGA), and scanning electron microscopy (SEM). The study investigated the effects of adsorbent quantity, adsorbate concentration, temperature, time, and pH on adsorption efficiency and capacity. The Langmuir adsorption isotherm provided the best fit for uranium (VI) adsorption. The results showed that rapid adsorption occurred within the first 100 min, with the rate slowing down until equilibrium was reached after 360 min. The pseudo-second-order kinetic model best described the adsorption process.

Heavy metal contamination in soil poses significant environmental and geotechnical challenges, requiring effective stabilization to limit contaminant mobility, enhance soil stability, and reduce deformation. This study investigates the dynamic response and microstructural changes in heavy metal-contaminated clayey sand, emphasizing the effects of clay type (kaolin and bentonite) and zeolite stabilization at varying contents (5%, 10%, and 15%). Laboratory tests, including cyclic triaxial, bender element, adsorption, sedimentation, pH measurements, Atterberg limits, and SEM analyses, were performed. Results reveal that contamination significantly reduces liquefaction resistance, with kaolin-based mixtures more susceptible than bentonite-based ones due to differences in plasticity, specific surface area, and swelling capacity. Zeolite stabilization, especially at 10% content, improves resistance by strengthening the soil structure and mitigating pore pressure under cyclic loading. Contamination affects shear modulus and damping ratio differently for kaolin and bentonite mixtures, with zeolite amplifying these impacts at higher contents through enhanced particle dispersion. Heavy metal adsorption increases with bentonite and zeolite addition, with bentonite exhibiting 180% greater lead adsorption than kaolin. Optimal adsorption performance is achieved with 10% zeolite. Microstructural analysis indicates contamination disrupts hydrogen bonding of kaolin, induces flocculation in bentonite, and has minimal effect on the stable structure of zeolite. These findings highlight the importance of clay type, zeolite content, and soil composition in mitigating contamination effects, providing insights into effective soil stabilization strategies.

Uranium (U) resources play a crucial role in energy utilization; however, uranium contamination in wastewater and soil has caused severe damage to the ecosystem and human health. Addressing this challenge requires the development of cost-effective and environmentally sustainable remediation materials. This review highlights the environmental merits of biochar-based materials in uranium decontamination, focusing on the diverse applications of modification techniques for enhancing the properties of pristine biochar. By analyzing over 110 relevant studies, the review demonstrates that biochar derived from various biomass sources, with proper modification, could exhibit high adsorption capacities for immobilising uranium in aqueous and soil environments. The primary removal mechanisms identified include physical adsorption and chemical reduction. These works indicate that biochar, produced from green feedstocks and featuring superior reusability, represents a cost-effective, sustainable solution for uranium remediation. Moreover, its application aligns with carbon sequestration and waste valorization, supporting sustainable development goals. Looking ahead, the engineering performance-oriented biochar materials with tailored physicochemical properties hold significant promise for addressing uranium contamination challenges. This review provides a comprehensive evaluation of biochar-based materials as a green alternative for uranium remediation and offers valuable insights into advanced material modification strategies to enhance reactivity and effectiveness.

This study addresses the challenges posed by dispersive soil in various engineering fields, including hydraulic and agricultural engineering, by exploring the effects of physical adsorption on soil modification. The primary objective is to identify an environmentally friendly stabilizer that can alleviate cracking and erosion resulting from soil dispersivity. Activated carbon (AC), known for its porous nature, was examined for its potential to enhance soil strength and erosion resistance. The charge neutralization process was evaluated by monitoring pH and conductivity, in addition to a comprehensive analysis of microscopic and mineral properties. The results show that high sodium levels or low clay contents result in the dispersive nature of soil in water. However, the incorporation of AC can transform such soil into a non-dispersive state. Moreover, both soil strength and erosion resistance exhibited enhancements with increasing AC content and curing duration. The incorporation of AC resulted in a maximum 5.6-fold increase in unconfined compressive strength and a 1.8-fold increase in tensile strength for dispersive soil. Notably, a significant correlation was observed during the curing phase among soil dispersivity, mechanical properties, and pH values. Microscopic analyses revealed that the porous structure of AC facilitated a filling effect and enhanced adsorption capacity, which contributed to improved soil characteristics and reduced dispersivity. The release of hydrogen ions and the formation of aggregates promote water stability. Validation tests conducted on dispersive soil from northern Shaanxi demonstrated the efficacy of physical adsorption using AC as a viable method for modifying dispersive soil in the water conservancy hub. (c) 2025 Institute of Rock and Soil Mechanics, Chinese Academy of Sciences. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/ 4.0/).