Visible-LED-light-driven photocatalytic degradation of ofloxacin and ciprofloxacin by magnetic biochar modified flower-like Bi2WO6: The synergistic effects, mechanism insights and degradation pathways.

Bi 2 WO 6 possesses good stability but poor photocatalytic activity under visible light. Herein, the coupling of Bi 2 WO 6 , Fe 3 O 4 and biochar (Bi 2 WO 6 /Fe 3 O 4 /BC) was investigated to enhance the photocatalytic performance of Bi 2 WO 6 through facile hydrothermal method, which almost completely degraded ofloxacin (OFL) and ciprofloxacin (CIP) within 30 min under energy-saving visible LED irradiation. The superior photocatalytic activity of Bi 2 WO 6 /Fe 3 O 4 /BC was ascribed to the stronger visible light adsorption capacity and the lower recombination of electron-hole pairs. O 2 − played a major role during the photocatalytic reaction. The characterization results suggested that the introduction of biochar avoided the agglomeration of Bi 2 WO 6 microspheres and Fe 3 O 4 nanoparticles, at the same time, the biochar participated in OFL and CIP photodegradation by consuming different oxygen-containing functional groups. In order to further evaluate the application potential of Bi 2 WO 6 /Fe 3 O 4 /BC, the effects of environment factors and the application in different actual water were carefully investigated. Various transformation products and the possible degradation pathways of OFL and CIP were analyzed based on high resolution mass spectrometry (HRMS) results, moreover, the toxicity evaluation results of Escherichia coli indicated these intermediates products were less toxic compared OFL and CIP. Overall, Bi 2 WO 6 /Fe 3 O 4 /BC can provide a potential way for the application of photocatalytic technology in ambient wastewater purification. Unlabelled Image • Bi 2 WO 6 /Fe 3 O 4 /BC exhibited excellent removal rates of ofloxacin and ciprofloxacin. • Fe 3 O 4 and biochar promoted the light absorption property and charge separation. • O 2 − was the main active species in ofloxacin and ciprofloxacin degradation. • Hydroxylation and ring cleavage of these two drugs were main degradation pathway. • Bi 2 WO 6 /Fe 3 O 4 /BC had broad prospects in antibiotic-contaminated sewage treatment. [ABSTRACT FROM AUTHOR]