Peroxymonosulfate catalyzed by core/shell magnetic ZnO photocatalyst towards malathion degradation: Enhancing synergy, catalytic performance and mechanism

In the current investigation, the ZnO nanoparticles were anchored on SiO2@Fe3O4 (S@F) core/shell surfaces to prepare ZnO-SiO2@Fe3O4 (ZS@F) nanocomposite. Characterization techniques confirmed the successful synthesis of ZS@F magnetic core/shells. The photocatalytic activity of pure ZnO was enhanced after its integration with SiO2@Fe3O4. The catalyst in coupling with UV-C light and peroxymonosulfate (PMS) showed a good performance towards malathion (MTN) degradation. Under optimal operational parameters (pH: 7, [ZS@F]: 0.3 g/L, [PMS]: 2 mM), 79.3 and 62.4% of MTN (20 mg/L) and TOC were eliminated within 60 min, respectively. The positive-charged holes and HO center dot radicals were the main reactive species during degradation reaction. The stability of ZS@F was investigated and revealed approximately 18% decrease in MTN degradation efficiency after 5 concecutive cycles. Finally, ZS@F/PMS/UV system can be used as a promising oxidation process for efficient degradation of MTN, because of its high catalytic performance, high stability, easy recovery and co-generation of various oxidative agents.