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

CoFe 2 O 4 -CeO 2 composites with different CoFe 2 O 4 content were synthesized and used as catalysts for peroxymonosulfate (PMS) activation in water purification. Under the conditions of 200 mg/L 15%CoFe 2 O 4 -CeO 2 and 0.15 mM PMS, complete atrazine degradation was achieved in the 15%CoFe 2 O 4 -CeO 2 /PMS system. The pseudo-first-order rate constant ( k obs ) in 15%CoFe 2 O 4 -CeO 2 /PMS system (0.224 min −1 ) was 2.4 and 4.8 times of that in CoFe 2 O 4 /PMS system (0.092 min −1 ) and (CoFe 2 O 4  + CeO 2 )/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 CoFe 2 O 4 and CeO 2 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 − , HCO 3 − and NO 3 − , H 2 PO 4 − could promote atrazine degradation in 15%CoFe 2 O 4 -CeO 2 /PMS system by improving sulfate radical concentration in the reaction system. The main degradation intermediates of atrazine in the 15%CoFe 2 O 4 -CeO 2 /PMS and CoFe 2 O 4 /PMS systems were compared, as well as the degradation pathways. The toxicity analysis based on luminescent bacteria Vibrio fischeri indicated the superiority of 15%CoFe 2 O 4 -CeO 2 /PMS than CoFe 2 O 4 /PMS systems for ATZ degradation.