Efficient pesticide degradation through peroxydisulfate activation by magnetic Fe3S4 nanoparticle hydrogel composites: Unveiling the pivotal role of electron transfer mechanisms

In this study, a magnetic Fe₃S₄ lignin hydrogel (FSLH) catalyst was synthesized to activate peroxydisulfate (PDS) for the degradation of isoproturon (IPU). The composite material not only exhibited high efficiency in degrading IPU but also effectively decomposed various neonicotinoid insecticides. Experimental results indicated that the FSLH/PDS system degraded IPU via an electron transfer pathway (ETP), wherein the Fe(Ⅲ)−OS₂O₇⁻ complex, formed by FSLH and PDS, captured electrons from IPU, facilitating efficient degradation and generating Fe(IV). All reactive oxygen species (ROS), including SO₄•⁻, •OH, ¹O₂, and O₂^•−, as well as Fe(IV), contributed to IPU degradation, with ETP playing a dominant role. In real water matrices, increasing the [FSLH/PDS] dosage significantly enhanced IPU degradation efficiency, and the FSLH/PDS system remained highly effective in the presence of various inorganic anions and humic acid. Ultimately, IPU was oxidized into low-toxicity products, substantially reducing ecological risks. This study elucidates the non-radical reaction mechanism, providing a theoretical basis for the application of hydrogel composite nanocatalysts in pesticide wastewater treatment.