Enhanced double-exchange interactions enable the Co and Mn co-doped zinc ferrite rapid and efficient removal of tetracycline

For rapid and efficient removal of tetracycline (TC), a new cobalt (Co) and manganese (Mn) co-doped zinc ferrite (CoMnZFO) photoanode was synthesized in this study. Compared to the pure zinc ferrite (ZFO), CoMnZFO exhibited stronger enhanced light harvesting ability and a narrower band gap. Although there were oxygen vacancies in both CoMnZFO and ZFO lattices, CoMnZFO possessed more double-exchange interaction pathways in comparison with ZFO. Besides the Fe 2 + /Fe 3+ pathway, CoMnZFO also had the Mn 3+ /Mn 4+ pathway, which facilitates the transfer of photogenerated electrons ( e - ) and holes (h + ), thereafter enabling CoMnZFO better photoelectrocatalytic (PEC) activity. Since CoMnZFO had a significantly smaller Helmholtz layer resistance than ZFO, it enhanced TC adsorption onto its surface. Exposed to simulated solar light for 12 min, CoMnZFO was able to make the complete degradation of TC (20 mg/L, 70 mL) when a voltage of 0.2 V was applied, while ZFO only achieved a TC degradation rate of 50.85 ± 5.77 % under the same condition. In addition, CoMnZFO achieved a TC mineralization rate of 41.89 ± 1.72 %, while that of ZFO was 13.87 ± 1.94 %. Furthermore, a quantitative structure-activity relationship (QSAR) method was applied to evaluate the ecotoxicological impact of the degradation products. The results demonstrate that the toxicity and mutagenicity of TC were weakened after experiencing the PEC treatment of CoMnZFO. Overall, this work offers a rapid and efficient way for PEC removal of TC-contaminated wastewater.