Degradation of sulfamethazine sodium salt by peroxymonosulfate activated by biochar supported CoFe2S4: Performance, mechanism and response surface method optimization

The persulfate oxidation process plays a critical role in eliminating antibiotics in wastewater, so it is urgent to develop a cheap, environmentally friendly and effective catalyst. In this study, CoFe 2 S 4 /BC catalyst was synthesized by a two-step hydrothermal method and combined with peroxymonosulfate (PMS) to degrade sulfamethazine sodium salt (SMT). The degradation results can be effectively predicted by establishing the response surface model. In order to maximize the removal rate of SMT, the optimization conditions are: catalyst dosage is 0.8 mg·L −1 , PMS dosage is 0.5 mM, the pH value is 9.0 and the predicted degradation rate of SMT is 86.87% under these conditions. Also, the effects of PMS dosage, catalyst dosage, pH value and coexisting substances in the water on the degradation of SMT were also systematically studied. Besides, In the CoFe 2 S 4 /BC/PMS system, there are both free radical and non-free radical pathways, in which the contribution of SO 4 · - was dominant. And the possible reaction mechanism and degradation path of SMT was proposed. In consequence, these results describe that CoFe 2 S 4 /BC is an excellent catalytic material and can be regarded as a catalyst for the catalytic degradation of antibiotics in wastewater treatment. • CoFe 2 S 4 /BC catalyst was successfully synthesized. • SMT could be degraded by CoFe 2 S 4 /BC by activating peroxymonosulfate. • The degradation pathways of SMT were proposed and confirmed. • The experimental conditions were optimized by response surface method. • The reaction mechanism of CoFe 2 S 4 /BC was elucidated.