Dual modification based on electrostatic repulsion of bentonite and SPR effect of Bi facilitate charge transfer of Bi2WO6 for antibiotics degradation.

Abstract

Development of efficient photocatalysts is vital for light-driven removal of refractory antibiotics. Herein, Bi2WO6 microspheres were successfully anchored on the surface of bentonite, and metallic Bi was reduced in-situ by a one-step solvothermal method. Notably, the Bi/Bi2WO6/BT with a mass ratio of 0.15:1:0.1 exhibited the best photocatalytic activity toward degradation of tetracycline (TC) and ciprofloxacin (CIP) after 120min of visible light irradiation, and their reaction rate constants were 8.0 and 5.5 folds higher than that of pristine Bi2WO6, respectively. The boosted photocatalytic activity over Bi/Bi2WO6/BT was ascribed to the establishment of electrostatic repulsion and SPR effect, which synergistically promoted charges transfer, thus achieving more h+ and ·O2- radical generation. Moreover, possible TC and CIP degradation pathways over Bi/Bi2WO6/BT were proposed based on the identified intermediates, and most of the intermediates were less toxic than TC and CIP. The study provides options to develop high-efficiency photocatalytic composites for contaminants elimination using semiconductors and readily available bentonite.