Efficient peroxymonosulfate activation by CoFe2O4-CeO2 composite: Performance and catalytic mechanism

CoFe2O4-CeO2 composites with different CoFe2O4 content were synthesized and used as catalysts for peroxymonosulfate (PMS) activation in water purification. Under the conditions of 200 mg/L 15%CoFe2O4-CeO2 and 0.15 mM PMS, complete atrazine degradation was achieved in the 15%CoFe2O4-CeO2/PMS system. The pseudo-first-order rate constant (kobs) in 15%CoFe2O4-CeO2/PMS system (0.224 min−1) was 2.4 and 4.8 times of that in CoFe2O4/PMS system (0.092 min−1) and (CoFe2O4 + CeO2)/PMS system (0.047 min−1). The main reactive species were verified through various quenching experiments and electron paramagnetic resonance tests, and the concentration of two main radicals was calculated. In addition, the interaction between CoFe2O4 and CeO2 involving Co(III)/Co(II), Fe(III)/Fe(II), and Ce(IV)/Ce(III) redox recycle for accelerating the degradation of organic compounds was explored. In addition, different from Cl−, HCO3− and NO3−, H2PO4− could promote atrazine degradation in 15%CoFe2O4-CeO2/PMS system by improving sulfate radical concentration in the reaction system. The main degradation intermediates of atrazine in the 15%CoFe2O4-CeO2/PMS and CoFe2O4/PMS systems were compared, as well as the degradation pathways. The toxicity analysis based on luminescent bacteria Vibrio fischeri indicated the superiority of 15%CoFe2O4-CeO2/PMS than CoFe2O4/PMS systems for ATZ degradation.