The water infiltration rules of five different homogeneously or heterogeneously-constructed soil samples were determined to select the best soil construction module for refuse dump reclamation in the opencast mines of the Shanxi-Shaanxi-Inner Mongolia energy circle. Five treatments, including three homogeneous soil samples consisting of sandy soil, Montmorillonite-enriched sandstone, and sand-Montmorillonite-enriched sandstone mixture, together with two heterogeneous soil samples composed of sandy soil + Montmorillonite-enriched sandstone + sandy soil and sandy soil + sandy − Montmorillonite-enriched sandstone mixture (7:3) + sandy soil. Three replicates of each treatment were prepared in the indoor pillars to measure the infiltration process by auto-recording geometry, to investigate the infiltration features of various soil configurations by testing their infiltration rate, cumulative infiltration capacity, wetting front migration, and profile soil content, and to evaluate the infiltration of newly constructed soil in the natural conditions of the research area. The experiment demonstrated that the addition of Montmorillonite-enriched sandstone into sandy soil significantly slowed down soil water infiltration, especially in the heterogeneous soils. Traditional models perfectly simulated the soil water infiltration in the three homogeneous soils in which soil infiltration capacity could be segmentally fitted by Kostiakov model and linear model, and wetting front could be fitted by a power function. Compared with the homogeneous soil samples, heterogeneous soil could reduce the direct surface runoff and deep percolation, and is an idealized structure for soil reconstruction in opencast coal mine dump.

As a common necessity, masks have been used a lot in recent years, and the comprehensive utilization of waste masks has become a research priority in the post-COVID-19 pandemic era. However, traditional disposal methods suffer from a range of problems, including poor utilization and insecurity. To explore new solution ideas and efficiently utilize waste resources, waste masks and biomass wastes were used as raw materials to prepare mask-based biochar (WMB), bio-oil, and pyrolytic gas via oxygen-limited co-pyrolysis in this study. The obtained solid–liquid–gas product was systematically characterized to analyze the physicochemical properties, and the adsorption properties and mechanisms of WMB on the environmental endocrine bisphenol A (BPA) were investigated. The co-pyrolysis mechanisms were also studied in depth. Furthermore, the strengths and weaknesses of products prepared by co-pyrolysis and co-hydrothermal synthesis were discussed in comparison. The results indicated that the waste masks could shape the microsphere structure, leading to richer surface functional groups and stable mesoporous of WMB. Here, the risk of leaching of secondary pollutants was not detected. The theoretical maximum adsorption of BPA by WMB was 28.73 mg·g⁻¹. The Langmuir and Pseudo-second-order models optimally simulated the isothermal and kinetic adsorption processes, which are a composite of physicochemical adsorption. Simultaneous pyrolysis of mask polymers with biomass polymers produces bio-oil and pyrolytic gas, which is rich in high-quality aliphatic and aromatic compounds. This could have potential as an energy source or chemical feedstock. The co-pyrolysis mechanisms may involve the depolymerization of waste masks to produce hydrocarbons and H radicals, which in turn undergo multi-step cleavage and oligomerization reactions with biomass derivatives. It is recommended to use the co-pyrolysis method to dispose of waste masks, as the products obtained are significantly better than those obtained by the co-hydrothermal method. This work provides a new contribution to the resourcing of waste masks into high-quality products.

Hexavalent Chromium (Cr(VI)) contamination in soils poses significant ecological risks due to its mobility and toxicity, with retention mechanisms governed by interactions between soil properties and Cr(VI). However, the quantitative roles of key soil parameters in Cr(VI) retention remain poorly resolved, particularly across diverse soil types. This study investigated Cr(VI) retention behaviors in 16 Chinese soils (15 types) through batch experiments, isothermal adsorption model, correlation analysis and path analysis. The results showed that the retention of Cr(VI) in acidic soils was significantly higher than in alkaline soils. Acidic soils (pH < 5.4) with higher concentrations of exchangeable Fe(II) (Exch-Fe(II)) exhibited strong Cr(VI) holding capabilities,while Alkaline soils (pH > 7.3) with highest content of CaCO ₃ show negligible Cr(VI) reactions.Cr(VI) retention was high at soil pH values below approximately 5.5, but declined sharply at higher pH values. The Langmuir model was only suitable for describing acidic soils (pH < 5.4), while the Freundlich equation was applicable to all soils. Correlation analysis revealed that soil pH, the content of soil organic matters(SOM), Exch-Fe(II), complexed iron (Com-Fe), and clay were significantly related to the Cr(VI) retention ( p < 0.01), whereas the CaCO ₃ content was negatively related to the Cr(VI) retention ( p < 0.05).Path analysis revealed that soil pH was the most important direct factor, followed by Exch-Fe(II), Com-Fe, clay, in determining Cr(VI) retention in natural soil. CEC and CaCO ₃ content had only limited directly effects on the Cr(VI) retention. Additionally, The content of SOM, Amorphous iron oxides(Amo-Fe), and Easily reducible manganese(Er-Mn) content had little directly effect on Cr(VI) retention. To validate these findings, Cr(VI) retention was measured in all soils after adjusting their pH to 4.3, 6, and 8. The results highlighted soil pH and Exch-Fe(II) content were the most decisive factors for evaluating Cr(VI) retention in natrual soils,whereas SOM content was an unreliable parameter for assessing this process.

Pharmaceutical residues in wastewater pose persistent ecological and public health risks, creating an urgent need for efficient and sustainable remediation technologies. MXene-based photocatalysts have attracted growing interest owing to their high electrical conductivity, tunable surface chemistry, abundant active sites, and excellent charge-transfer capability. This review summarizes recent advances in MXene-based photocatalytic systems for pharmaceutical wastewater treatment and renewable energy production. Key topics include pharmaceutical degradation pathways, reactive oxygen species generation, ecotoxicological implications, and the multifunctional roles of MXenes as conductive supports, electron mediators, and cocatalysts. Interfacial engineering strategies, including Z-scheme, S-scheme, and Schottky heterojunctions, are discussed with respect to light absorption, charge separation, and interfacial redox reactions. Practical considerations, such as reactor design, life cycle assessment, and techno-economic feasibility, are also addressed. Finally, current challenges and future directions are highlighted, particularly scalable fluorine-free synthesis, improved oxidative stability, and machine learning-assisted material design. This review provides a concise framework for developing stable, efficient, and scalable MXene-based photocatalytic platforms for pharmaceutical wastewater remediation and sustainable energy generation.