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Rainfall runoff can mobilize heavy metals in industrial soils, posing environmental risks. The mobility and distribution of heavy metals in different industrial soil layers are often overlooked. This study employed dynamic leaching experiments in layered soil columns with DGT (the diffusive gradients in thin films) measurements and DIFS (DGT-induced fluxes in soils and sediments) model to describe the migration, availability, and resupply ability of metals at different depths in surface and deep soil columns of industrial soils. Results showed significantly higher available concentrations (C DGT and C Soln ) of Ni and Cd in surface soils compared to deep soils, likely due to the differences in soil physiochemical properties (contamination, pH, and soil texture). Continuous leaching promoted the migration of available Ni and Cd in surface soils. Maximum values of R Ni (0.79-0.91) and R Cd (0.75-0.80) were observed in the top layer (0-4 cm) of the surface soil, consistent with the trends of R Fe . Combined DGT and DIFS model analysis implied higher potential availability and resupply of Ni and Cd in surface soil columns. These findings highlight the importance of considering dynamic leaching effects on heavy metal transport, availability, and release in industrial soils., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

MXenes, such as Ti 3 C 2 T x , demonstrate tremendous potential as heavy metal adsorbents due to their abundant reaction sites, high hydrophilicity, controllable interlayer spacing, and inherent reduction ability. However, their structural dependent pollutant removal performances and the related mechanisms are far less studied. Therefore, the removing abilities of Cr(VI) from water on Ti 3 C 2 T x MXenes with different structures (multilayer (ML-) and delaminated (DL-) Ti 3 C 2 T x ) synthesized via several etching techniques were evaluated. Focusing on the most effective ML- and DL-Ti 3 C 2 T x obtained by acid/fluoride salt etching, the impacts of structural variations on the Cr(VI) removal performances were explored. Both ML- and DL-Ti 3 C 2 T x demonstrate outstanding Cr(VI) adsorption and reduction capabilities, achieving equilibrium within 500 min with capacities of 92.7 and 205 mg/g, respectively. The differences in removal mechanisms stemed from the varying adsorption and reduction capacities of two MXenes. ML-Ti 3 C 2 T x , with lower surface area and porosity, had low adsorption capacity but superior reduction ability, efficiently converting most Cr(VI) to Cr(III) (66.8%). Conversely, DL-Ti 3 C 2 T x exhibited better removal efficiency but a lower capacity for reduction (45.7%). Notably, although the partial reduction of DL-Ti 3 C 2 T x to TiO 2 results in its limited chemical reduction capacity, Ti 3 C 2 T x might serve as a co-catalyst for TiO 2 , boosting the photoresponsiveness of DL-Ti 3 C 2 T x or TiO 2 through Ti 3 C 2 T x /TiO 2 heterojunctions, thereby facilitating photocatalysis to realize the reduction of Cr(VI). Both Ti 3 C 2 T x exhibited both excellent Cr(VI) removal capacity and detoxification capacity, demonstrating their high potential in treating heavy metal pollutants in wastewater., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Although selenium is an essential nutrient, its contamination in water poses serious risks to human health and ecosystems. In this study, aluminum-modified bamboo biochar (Al-BC) was developed to reclaim Se(VI) from water. Compared to pristine biochar (BC), Al-BC had a larger specific surface area (176 m 2 /g) and pore volume (0.180 cm³/g). The modification, achieved by loading AlOOH and Al 2 O 3 particles onto the surface, enabled Al-BC to achieve a maximum adsorption capacity of 37.6 mg/g for Se(VI) within 2 hours and remove 99.6% of Se(VI) across a pH range of 3-10. The main adsorption mechanism of Se(VI) involved electrostatic attraction, forming outer-sphere complexes between Se(VI) and AlOOH sites on the biochar. The bioavailability of Se sorbed on the spent biochar (Al-BC-Se) was thus evaluated. It was discovered that Al-BC-Se successfully released Se(VI), which impacted the growth of wheat seedlings. The Se content reached 134 μg/g dry weight (DW) in wheat shoots and 638 μg/g DW in roots, significantly exceeding normal selenium content (<40 μg/g DW). By successfully applying the modified biochar to capture selenium from water through adsorption and then reusing it as an essential nutrient in soil, this study suggests the promising feasibility of the "removal-collection-reuse" approach for the circular economy of selenium in wastewater., Competing Interests: Declaration of Competing Interest ☐ The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. ☒ The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Jun Luo reports financial support was provided by National Natural Science Foundation of China. If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier Ltd.)

Nanoscale zerovalent iron (nZVI) has garnered significant attention as an efficient advanced oxidation activator, but its practical application is hindered by aggregation and oxidation. Coating nZVI with carbon can effectively addresses these issues. A simple and scalable production method for carbon-coated nZVI composite is highly desirable. The anti-oxidation and catalytic performance of carbon-coated nZVI composite merit in-depth research. In this study, a highly stable carbon-coated core-shell nZVI composite (Fe 0 @RF-C) was successfully prepared using a simple method combining phenolic resin embedding and carbothermal reduction. Fe 0 @RF-C was employed as a heterogeneous persulfate (PS) activator for degrading 2,4-dihydroxybenzophenone (BP-1), an emerging contaminant. Compared to commercial nZVI, Fe 0 @RF-C exhibited superior PS activation performance and oxidation resistance. Nearly 95% of BP-1 was removed within 10 min in the Fe 0 @RF-C/PS system. The carbon layer promotes the enrichment of BP-1 and accelerates its degradation through singlet oxygen oxidation and direct electron transfer processes. This study provides a straightforward approach for designing highly stable carbon-coated nZVI composite and elucidates the enhanced catalytic performance mechanism by carbon layers., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2024 The Authors.)