Applying a novel advanced oxidation process of activated peracetic acid by CoFe2O4 to efficiently degrade sulfamethoxazole

In this study, peracetic acid (PAA) is successfully activated by cobalt ferrite (CoFe2O4/PAA) to remove sulfamethoxazole (SMX). Increasing either PAA (25-200 mu M) or CoFe2O4 (25-200 mg/L) dose accelerated SMX degradation in the CoFe2O4/PAA system, and the best removal of SMX (87.3%) was acquired with 200 mu M PAA and 0.1 g/L CoFe2O4 at neutral condition. Addition of humic acid or HCO3- inhibited SMX removal, whereas Cl- had little impact. The redox cycle of Co3+/ Co2+ on the CoFe2O4 surface dominated PAA activation to produce organic radicals (R-O-center dot) including CH3C(O)O-center dot and CH3C(O)OO center dot accounting for SMX degradation. Based on the density functional theory (DFT) calculation and identified oxidation products, SMX transformation pathway was proposed to be initiated by electron transfer reaction with R-O-center dot. The insignificant variation of acute toxicity, the fine CoFe2O4 stability and the good removal of some other micro-organic pollutants suggested the potential applicability of the CoFe2O4/PAA system in degrading micro-organic pollutants.

Automated summary

In this study, peracetic acid (PAA) was successfully activated by cobalt ferrite (CoFe2O4/PAA) to remove sulfamethoxazole (SMX). The best removal efficiency of SMX was achieved under neutral conditions with 200 μM PAA and 0.1 g/L CoFe2O4. The redox cycle of Co3+/ Co2+ on the CoFe2O4 surface dominated PAA activation, producing organic radicals that accounted for SMX degradation. The potential applicability of the CoFe2O4/PAA system in degrading micro-organic pollutants was suggested based on the results of this study.