Construction of activated biochar/Bi 2 WO 6 and /Bi 2 MoO 6 composites to enhance adsorption and photocatalysis performance for efficient application in the removal of pollutants and disinfection

To synergistically enhance the adsorption and photocatalytic performance of Bi 2 WO 6 and Bi 2 MoO 6 , using activated biochar (ACB) as substrate, ACB-Bi 2 WO 6 and ACB-Bi 2 MoO 6 composites were facilely prepared by hydrothermal synthesis. Their adsorption–photocatalytic degradation effects on rhodamine B (RhB), tetracycline (TC), and norfloxacin (NOR) were comparatively investigated. Additionally, the effects of environmental factors, wastewater treatment tests, and disinfection were systematically studied, and the enhancement mechanisms and reasons for the degradation differences were highlighted. The results showed that ACB-Bi 2 WO 6 and ACB-Bi 2 MoO 6 were confirmed to form intimately contacted heterojunctions by various advanced characterization techniques. The introduction of ACB narrowed the band-gap energy of Bi 2 WO 6 and Bi 2 MoO 6 , and improved the visible light absorption range and specific surface area. The optimal loading ratios of ACB-Bi 2 WO 6 and ACB-Bi 2 MoO 6 were 1:1.06 and 1:0.58, respectively. The removal rate of ACB-Bi 2 WO 6 for high concentrations of RhB (200 mg·L −1 ), TC and NOR (50 mg·L −1 ) were 89.15%, 87.27%, and 72.17%, respectively, which were higher than those of ACB-Bi 2 MoO 6 and significantly stronger than those of Bi 2 WO 6 and Bi 2 MoO 6 . This was attributed to the more effective inhibition of photogenerated carrier recombination, higher absorbance, and uniform morphology via ACB-Bi 2 WO 6 . · OH and holes were dominant active species in photocatalysis, and the possible photogenerated carrier transfer path is type II heterojunction. Furthermore, ACB-Bi 2 WO 6 possessed good reusability, and the removal of RhB and TC from the actual wastewater exceeded 80.63% and 58.54%, respectively. The sterilization rates of ACB-Bi 2 WO 6 reached 99% and 95% for E. coli and S. aureus within 24 h, respectively. Therefore, ACB-Bi 2 WO 6 was more recommended for environmental applications. Graphical Abstract