Enhanced remediation of PFAS-metal co-contaminated soil by ceramsite supported Fe 3 O 4 -MoS 2 heterojunction as a high-performance piezocatalyst.

In this study, a novel piezoremediation system was developed to remediate an actual soil co-polluted by high contents of per- and polyfluoroalkyl substances (PFAS, 5725 μg/kg soil) and heavy metals (6455 mg/kg soil). Two piezocatalysts, MoS ₂ /ceramsite (MC) and Fe ₃ O ₄ -MoS ₂ /ceramsite (FMC), were synthesized using a facile hydrothermal-coprecipitation method. These two materials were employed to treat the co-contaminated soil in soil slurry environment under sonication. FMC exhibited significantly higher piezoremediation performance than MC, wherein 91.6% of PFAS, 97.8% of Cr ⁶⁺ ions and 81% of total metals (Cr, Cu, Zn and Ni) were removed from the soil after 50 min of the FMC piezoremediation process. FMC also exhibited the advantages of easy separation from the slurry phase and excellent reusability. In comparison with MC, the Fe ₃ O ₄ -MoS ₂ heterojunction in FMC can stabilize MoS ₂ particles on the surface of ceramsite granules, promote the separation of electron/hole pairs, accelerate charge transfer, therefore enhancing piezocatalytic performance. The electron spin resonance analysis and free radical quenching tests show that ^• OH was the dominant oxidative radical responsible for PFAS degradation. The count of bacteria and the bacterial community structure in the treated soil can be basically restored to the initial states after 30 days of incubation under nutrient stimulation. Overall, this study not only provides a deep insight on soil remediation process, but also offers an efficient and reliable technique for simultaneous decontamination of organic and metal pollutants in soil.
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.)