CuFe2O4/penicillin residue biochar heterogeneous Fenton-like catalyst used in the treatment of antibiotic wastewater: Synthesis, performance and working mechanism

A heterogeneous Fenton-like catalyst, CuFe2O4/penicillin residue biochar (CuFe2O4/PRBC), was synthesized and used to treat antibiotic wastewater. The physicochemical properties of PR, PRBC, and CuFe2O4/PRBC were characterized by a series of methods. CuFe2O4/PRBC showed better performance (removal rate constant of tetracycline = 0.0599 min−1) than those of CuFe2O4 (0.0458 min−1), PRBC (0.0244 min−1), and a direct physical mixing of CuFe2O4 with PRBC (0.0285 min−1). Under the optimal conditions (fresh CuFe2O4/PRBC loading = 0.4 g·L−1, H2O2 dosage = 30 mmol·L−1, the range of initial pH was 3–9), the removal rate of tetracycline was >95 % within 90 min, and the removal rate slightly decreased to 90.7 % in the fifth use of CuFe2O4/PRBC. Besides tetracycline, CuFe2O4/PRBC catalyzed Fenton-like process can effectively oxidize sulfamethoxazole, oxytetracycline, and ciprofloxacin with the corresponding removal rates of 99.4 %, 97.1 %, and 88.8 %, and effectively remove COD from oxytetracycline and cephalosporin real production wastewaters, respectively, satisfying the discharge standard of GB 21903–2008. The main oxidative free radicals were ·OH and ·O2−/HO2·, and the working mechanism of CuFe2O4/PRBC was the synergy process between adsorption and catalytic oxidation, where the separate redox recycles of ≡Fe(III)/≡Fe(II) and ≡Cu(II)/≡Cu(I) and the redox reaction between ≡Fe(III) and ≡Cu(I) were critical steps.