Enhanced visible light photocatalytic performance with metal-doped Bi2WO6 for typical fluoroquinolones degradation: Efficiencies, pathways and mechanisms

• Published in: Chemosphere (Oxford) Vol. 252; p. 126577
• Main Authors: Zhu, Fengyi, Lv, Yunzhe, Li, Jianju, Ding, Jing, Xia, Xinhui, Wei, Liangliang, Jiang, Junqiu, Zhang, Guangshan, Zhao, Qingliang
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.08.2020
• Subjects: Bi2WO6; Fluoroquinolones; Mechanisms; Metal-ion doping; Photocatalytic degradation; Fluoroquinolones; Photocatalytic degradation; Mechanisms; Bi2WO6; Metal-ion doping
• ISSN: 0045-6535; 1879-1298
• DOI: 10.1016/j.chemosphere.2020.126577

To clarify the photocatalytic mechanisms of metal-doped Bi2WO6 for fluoroquinolones (FQs) degradation, the effects of the chemical characteristics of four metals, molar ratios of the doped metals, morphology of the catalysts, and electrostatic interactions on the degradation of norfloxacin (NOR) and ciprofloxacin (CIP) were evaluated under visible light irradiation. Experimental results implied that the doping of Mg2+, Fe3+, Zn2+ and Cu2+ dramatically improved the photodegradation of Bi2WO6 for NOR and CIP removal, in which 1% Mg/Bi2WO6 exhibited the highest degradation rate of 89.44% for NOR and 99.11% for CIP. Photodegradation of NOR fitted to the pseudo-first-order model (k1 value of 0.02576 min−1), whereas that of CIP be better described by pseudo-second-order model. Moreover, the two FQs photodegradation pathways and the possible intermediates were summarized. The mechanisms of the metal dopants for the enhancement of photocatalytic activity were attributed to its enhanced specific surface area, electrostatic absorption, as well as the significant photogeneration of ·O2− and h+. Also, the photocatalyst exhibited a high stability with 78.5% photocatalytic performance after four cycles of repeated usage. [Display omitted] •Mg doped Bi2WO6 exhibited the highest removal rate of FQs, followed by Fe, Zn and Cu.•More than 89% NOR and 99% CIP degradation were obtained using Mg/Bi2WO6 as catalysts.•Generated ·O2− and h+ are the main reactive species for NOR and CIP photodegradation.•Doped Mg2+ served as an electron pool and enhanced the photogeneration of ·O2−.•Electrostatic adsorption, declined energy band gaps enhanced Mg/Bi2WO6 photocatalyst.