Efficient degradation of organic contaminants by magnetic cobalt ferrite combined with peracetic acid

Abstract

In this study, a novel heterogeneous peracetic acid (PAA)-based advanced oxidation process (AOP), viz. cobalt ferrite combined with PAA (CoFe2O4/PAA), was used to degrade organic contaminants. The best pH for rhodamine B (RhB) degradation in CoFe2O4/PAA system was at 7, and approximately 95% RhB could be removed within 10 min at this pH. Radical scavenging experiments indicated that organic radicals (i.e., CH3COO• and CH3COOO•) were the dominant reactive species for RhB degradation. The X-ray photoelectron spectroscopy (XPS) analysis for the fresh and used catalysts suggested that the catalytic reaction mainly occurred on the surface of the catalyst. Increasing PAA dosage and CoFe2O4 dosage could enhance the removal of RhB, while excess CoFe2O4 dosage inhibited its degradation probably due to the clumping effect of magnetic nanoparticles. Five degradation products of RhB by CoFe2O4/PAA were identified and two degradation pathways of RhB were subsequently proposed, including bond cleavage and hydroxylation. CoFe2O4 exhibited an excellent stability and reusability, and the removal rate of RhB could maintain at 92.4% after four cycles. Several kinds of organic contaminants were selected to evaluate the applicability of CoFe2O4/PAA system, and the results suggested that CoFe2O4/PAA system exhibited a selectivity for different contaminants.