Efficient visible-light photocatalysis of chloramphenicol using novel engineered biochar-based Ti-doped Bi₂WO₆ composite: Mechanisms, degradation pathways, and applications

A novel engineered biochar (ACB)-based Ti-doped Bi2WO6 composite (Ti-Bi2WO6@ACB) was synthesized via a one-step hydrothermal reaction for the efficient degradation of chloramphenicol (CAP) and extensive environmental applications. Multiple characterization techniques, CAP degradation effects, total organic carbon (TOC) removal, effects of environmental factors, recycling tests, actual wastewater treatment, enhancement strategies, and disinfection effects were systematically evaluated. It was found that Ti-Bi2WO6@ACB is a Ti3+ self-doped TiO2/Bi2WO6/ACB ternary heterogeneous photocatalyst. The introduction of ACB and Ti doping enhanced the elemental composition, oxygen-containing functional groups, defect structure (oxygen vacancies), visible-light absorption, and active sites. Moreover, Ti-Bi2WO6@ACB effectively inhibited the recombination of photogenerated carriers. The removal efficiency of Ti-Bi2WO6@ACB for 50 mg center dot L-1 CAP was 92.44 % at 120 min of irradiation, and the TOC removal rate was 67.72 %, which was significantly higher than that of the control treatment. Ti-Bi2WO6@ACB is reusable and photostable, with approximately 99 % sterilization of Staphylococcus aureus and Escherichia coli within 10 min of light irradiation and 48 h of cultivation. The addition of H2O2, ultrasonication, heating, and blowing air in the system improved the photocatalytic efficiency. The ultrasound enhancement mechanisms are related to the effects of cavitation, microjets, and photocatalysis coupled with sonocatalysis. CAP degradation was dominated by (OH)-O-center dot, O-center dot(2)-, and h(+). The doping of Ti3+/TiO2 generated more defects and O-center dot(2)-, and the ACB acted as a carrier to prevent the agglomeration of TiO2 and Bi2WO6. Further, the degradation process of CAP was documented and the degradation pathways may include hydroxylation addition, methanol denaturation, substitution, C-N bond breaking, oxidation, hydrolysis, and decarboxylation reactions. The research presents fresh insights into the development of high-performance engineered biochar-based composite for environmental detoxification.