Enhanced photocatalytic degradation of ciprofloxacin over Bi2O3/(BiO)2CO3 heterojunctions: Efficiency, kinetics, pathways, mechanisms and toxicity evaluation

• Published in: Chemical engineering journal (Lausanne, Switzerland : 1996) Switzerland : 1996), 2018-02, Vol.334, p.453-461
• Main Authors: Chen, Meijuan, Yao, Jie, Huang, Yu, Gong, Han, Chu, Wei
• Format: Article
• Language: English
• Subjects: Bi2O3/(BiO)2CO3; Ciprofloxacin; Degradation mechanism; Kinetics model; Toxicity
• ISSN: 1385-8947; 1873-3212
• DOI: 10.1016/j.cej.2017.10.064

[Display omitted] •Bi2O3/(BiO)2CO3 heterojunction was superior than the pristine components.•Kinetics model in terms of operating parameters fitted well to experimental data.•Inorganic anions had a different degree of influence on the CIP decay efficiency.•The decay mechanism was proposed by both experiment and theoretical calculation.•Efficient alleviation on TOC and toxicity were obtained. In this study, the degradation of antibiotic ciprofloxacin (CIP) over Bi2O3/(BiO)2CO3 heterojunctions under simulated solar light irradiation (SSL-Bi2O3/(BiO)2CO3) was examined for the first time. The results showed that the Bi2O3/(BiO)2CO3 heterojunctions dramatically improved CIP decay efficiency. The effect of parameters showed that the CIP decay was optimized with the Bi2O3/(BiO)2CO3 dosage of 0.5 g/L and a wide pH range of 4.0–8.3, based on which, a kinetic model was derived to predict the remaining CIP concentration. It was found that the presence of anions like SO42−, NO3− and HCO3− decelerated the CIP decay, while the co-existence of Cl− accelerated the CIP decay. Six degradation intermediates were identified by ultra-performance liquid chromatography coupled with mass analyzer (UPLC/MS) and ion chromatographic (IC) analysis, and the decay pathways and degradation mechanism of CIP were proposed by combining the experiment data with theoretical calculation of frontier electron densities. Hydroxyl radical’s reaction, photo-hole (h+) oxidation and reductive defluorination were found to involve in the CIP decay. The efficient alleviation on total organic carbon (TOC) and toxicity indicated that the complete mineralization and de-toxicity are possible by this system with sufficient reaction time.