Absolute lomefloxacin degradation over visible-light-driven heterojunction: experimental and theoretical insights

Abstract

Rising lomefloxacin (LMF) contamination in water raises growing health and ecological concerns, driving demand for effective removal strategies. Here we report a visible-light-responsive Fe-BiOCl/Bi2WO6 heterojunction that achieves complete degradation of LMF within 6 h under optimized conditions (pH 7.0, 5 mg per L LMF, 0.2 g per L catalyst, 500 W). Iron doping markedly enhances visible-light absorption and promotes the separation and migration of photogenerated electron–hole pairs. Mechanistic studies reveal that ˙O2− generated at the conduction band of Fe-BiOCl, ˙OH at the valence band of Bi2WO6, and h+ are the primary active species, contributing approximately 76.75%, 63.22%, and 74.28% to LMF degradation, respectively. Toxicity assessment shows that the degradation products pose substantially lower risks to aquatic organisms, with reduced acute, developmental, and mutagenic effects compared to intact LMF. DFT calculations on the electronic structure and reaction pathways corroborate the experimental results, providing a mechanistic rationale for the enhanced photocatalytic performance. This work offers an efficient visible-light-driven catalyst for LMF removal and a mechanistic framework for designing doped heterojunction photocatalysts for antibiotic-contaminated water treatment.