Magnetic visible-light activated photocatalyst ZnFe2O4/BiVO4/g-C3N4 for decomposition of antibiotic lomefloxacin: Photocatalytic mechanism, degradation pathway, and toxicity assessment

• Published in: Chemosphere (Oxford) 2022-07, Vol.299, p.134320-134320, Article 134320
• Main Authors: Truong, Hai Bang, Huy, Bui The, Ray, Schindra Kumar, Gyawali, Gobinda, Lee, Yong-Ill, Cho, Jinwoo, Hur, Jin
• Format: Article
• Language: English
• Subjects: Antibiotics; Degradation pathway; Density functional theory calculation; Ecotoxicology; G-C3N4; Visible light-activated photocatalysis
• ISSN: 0045-6535; 1879-1298
• DOI: 10.1016/j.chemosphere.2022.134320

Magnetic ZnFe2O4/BiVO4/g-C3N4 (ZBC) composites were prepared via a facile hydrothermal and calcination method for the degradation of a representative antibiotics lomefloxacin (LFX) under visible light irradiation. The optimal photocatalyst ZBC-10 with a ZnFe2O4:BiVO4:g-C3N4 mass ratio of 1:8:10 performed 96.1% removal of LFX after 105 min of illumination. The excellent performance is ascribed to the effective construction of heterojunctions and its capacity to form a double Z-scheme charge transmission pathway among the hosts in ZBC-10. The composite enhanced the separation and migration of photoexcited charge carriers and the effective generation of multiple active radicals including ·OH, ·O2−, and 1O2. The LFX degradation process, identified based on an integrated HPLC-Q-TOF-MS analysis and density functional theory computation of the Fukui indices, comprised of three pathways initiated by the opening of the piperazinyl ring, separation of piperazinyl and quinoline moieties, and cleavage of the pyridine ring on the quinoline moieties. Ecotoxicological evaluation confirmed the reduced toxicity of transformation intermediates over photocatalysis. Convenient magnetic recovery, high performance, and high recyclability made ZBC-10 a promising visible-light-activated photocatalyst for practical implementation in eliminating antibiotics from wastewater. [Display omitted] •An efficient photocatalyst was synthesized for LFX removal under visible light.•Optimal composite ZBC-10 showed an excellent performance in LFX removal.•It featured wide-range VL-harvesting ability and effective double Z-scheme separation.•Degradation pathways were unraveled using HPLC-Q-TOF-MS and DFT computation.•Ecotoxicity of LFX and its intermediates are evaluated using multiple methods.