Facile synthesis of activated biochar/BiVO4 heterojunction photocatalyst to enhance visible light efficient degradation for dye and antibiotics: applications and mechanisms

The applications of biochar in catalysis have become a research hotspot, but studies using activated biochar (ACB) and enhanced mechanisms are limited. To improve the photocatalytic performance of BiVO4, the nano-photocatalyst (ACB-BiVO4) was synthesized via a facile hydrothermal reaction. Various characterization techniques were performed, and the adsorption-photodegradation of the organic pollutants rhodamine B (RhB), tetracycline (TC), norfloxacin (NOR), and chloramphenicol (CAP) under visible light were investigated. Meanwhile, the effects of loading ratios, initial concentrations, recycling tests, more enhancement strategies, actual wastewater treatment, and disinfection effects on photocatalysis of ACB-BiVO4 were comprehensively evaluated. The results confirmed that the tetragonal phase BiVO4 was successfully composited onto the support ACB forming heterojunction, which displayed the best performance at a mass ratio of 1:0.62. The degradation rate by ACB-BiVO4 reached 84.52% for RhB at a kinetic constant of 0.0133 min(-1), which was 5.78 times higher than pure BiVO4. ACB-BiVO4 completely removed RhB and TC from the investigated surface water and removed more than 73.50% of RhB and TC from industrial wastewater. ACB-BiVO4 had excellent disinfection effects on E. coli and Staphylococcus aureus with a sterilization rate of over 99% at 12 h center dot OH and holes were dominant active species and the enhancement mechanism is associated with the heterojunction. ACB-BiVO4 expanded the visible light (similar to 545 nm) absorption and reduced the band gap (2.26 eV), and effectively inhibited the photogenerated carriers recombination. The unique structure (defects) and surface properties (functional groups and environmentally persistent free radicals) of ACB were found to play a critical role. (C) 2022 The Author(s). Published by Elsevier B.V.