Photochemical remediation of soil co-contaminated with tetracycline and Cr(VI) using S-scheme BiFeO3/Cl-g-C3N4 heterostructure photocatalyst: Performance, microbial community changes and phytotoxicity assessment

Within the domain of animal husbandry, the misuse of antibiotics in conjunction with elevated levels of heavy metals in feed has led to the contamination of agricultural soils with these metals and antibiotics. In this study, S-scheme heterojunction photocatalyst, BiFeO 3 /Cl-g-C 3 N 4 , was synthesized for the photochemical remediation of tetracycline (TC) and Cr(Ⅵ) in co-contaminated soil, utilizing pyrolysis methods. Following an 8-h photocatalytic reaction, 89.6 % of TC and 75.7 % of Cr(Ⅵ) were effectively removed in soil with the application of BiFeO 3 /Cl-g-C 3 N 4 at a mass ratio of 5 %. The diversity of microbial communities in the remediated soil increased, with a shift in dominant genera from redox bacteria to nutrient bacteria associated with carbon and nitrogen cycling. Moreover, the incorporation of BiFeO 3 /Cl-g-C 3 N 4 in the remediation of soil contamination at depths ranging from 0 to 20 cm resulted in reductions of 40.2 % and 50 % in TC and Cr(Ⅵ) concentrations in subsoil layers, respectively, after 21-days of sunlight irradiation. In comparison to the contaminated group soil, soil from the remediation treatment demonstrated increased growth potential for cabbage and spinach. This work definitely demonstrates that this soil photochemical remediation method based on BiFeO 3 /Cl-g-C 3 N 4 is technologically feasible and has immense potential in the application of remediation of organic pollutants and heavy metals co-contaminated soils.