One-step solvothermal synthesis of wood flour carbon fiber/BiOBr composites for photocatalytic activation of peroxymonosulfate towards sulfadiazine degradation: Mechanisms comparison between photo, chemical and photo-chemical oxidation processes

Abstract

Facile preparation of novel catalysts which can effectively activate peroxymonosulfate (PMS) under visible light is of great significance for rapid degradation of refractory organic chemicals in water. Herein, one-step solvothermal process was introduced to prepare carbon nanofiber incorporated bismuth oxybromide (BiOBr/SCF) composites, in which commercial wood flour was in-situ converted to carbon fiber with graphitic structure and incorporated with BiOBr via the process. At the existence of PMS, the prepared composites exhibited prominent visible-light photocatalytic degradation capability towards sulfadiazine (SDZ) with satisfying adaptability and recyclability. Specifically, the apparent pseudo-first order kinetic constant of BiOBr/SCF-180/PMS/visible light system (0.0724 min−1) exceeded those of both BiOBr/SCF-180/PMS (0.0462 min−1) and BiOBr/SCF-180/visible light (0.0111 min−1) systems. An integrated mechanism in the BiOBr/SCF/PMS/visible light system was elucidated through comparing the mechanisms amongst photo-oxidation, chemical oxidation and photo-chemical oxidation systems, in which photo-induced electron and hole, Bi3+/Bi5+ redox couple, graphitic structure and oxygen functional groups in the SCF all participated in the generation and conversion of the active species. The possible SDZ degradation pathway was also proposed. This work demonstrates a novel strategy to prepare high-efficient catalysts in the field of wastewater treatment.