Synergistic BiVO4/N, S co-doped municipal sludge-derived biochar composite for enhanced photocatalytic degradation of organic pollutants

Environmental pollution stemming from pharmaceutical products and textile effluents is increasing daily. Photocatalytic degradation is a viable remediation technique for such organic compounds. BiVO₄ (BVO) has gained attention as a visible light photocatalyst due to its easy preparation process and low cost. However, the high recombination rate of photogenerated charges limits the photocatalytic efficiency of BVO. To overcome such limitations and enhance the overall wastewater decontamination performance, a N, S-co-doped municipal sludge (NSMS)-derived biochar is utilized as support material. Composites having various BVO and NSMS biochar mass ratios were prepared to study the effect of NSMS biochar addition. The photocatalytic performance was evaluated using Rhodamine B and Ciprofloxacin as representative compounds for textile dye and pharmaceutical products, respectively. The BVO–NSMS composites demonstrated 2- and 3.5 times faster degradation for Rhodamine B and Ciprofloxacin, respectively, compared to the pristine BVO material. The XRD, FT-IR, UV-DRS, XPS, and EIS techniques were carried out to elucidate the observed synergistic effect of NSMS biochar inclusion in the BVO-based composite. The NSMS biochar provides adsorption sites for pollutant molecules and delays the recombination of the generated electron-hole pair of BVO material. Additionally, the RSM and ANOVA statistical tools were employed to determine the optimized degradation parameters. The presented NSMS-incorporated BVO composite valorizes the municipal sludge waste and can be applied as a photocatalyst for mitigating organic contamination.