ZIF-8-derived ZnO/CoFe2O4 heterojunction for synergistic photocatalytic-peroxymonosulfate activation: accelerated ciprofloxacin degradation via type II charge transfer

ZIF-8-derived ZnO/CoFe 2 O 4 removes 99.12% ciprofloxacin in 6 min under visible light. • Type II band alignment drives directional electron transfer, suppressing carrier recombination. • Dual-channel PMS activation via photoelectron reduction and Co/Fe redox cycling. • Over 99% efficiency retained after five cycles in actual surface water and groundwater. Fluoroquinolone antibiotics in aquatic environments threaten ecosystems and human health by spreading antimicrobial resistance. This study synthesized a magnetically recoverable ZnO/CoFe 2 O 4 heterojunction using ZIF-8-derived porous ZnO as substrate via solvothermal method. The optimized composite achieved 99.12% ciprofloxacin removal within 6 min under visible light with peroxymonosulfate. XPS evidence supports Type II heterojunction formation with directional electron transfer with directional electron transfer from ZnO to CoFe 2 O 4 . A dual-channel PMS activation mechanism is proposed involving direct PMS reduction by photogenerated electrons and SO 4 ⁻ generation through Co 2 ⁺/Co 3 ⁺ and Fe 2 ⁺/Fe 3 ⁺ redox cycles. EPR identified 1 O 2 and SO 4 ⁻ as dominant reactive species. The catalyst maintained excellent stability with over 99% efficiency after five cycles. LC-MS revealed piperazine ring cleavage, decarboxylation and defluorination pathways leading to deep oxidative degradation. This work provides an efficient strategy for antibiotic wastewater treatment using magnetically separable photocatalysts with synergistic photo-oxidation and persulfate activation capabilities. Download: Download high-res image (205KB) Download: Download full-size image