Efficient degradation of carbamazepine by organo-montmorillonite supported nCoFe2O4-activated peroxymonosulfate process

Abstract

Carbamazepine (CBZ) is one of most frequently detected pharmaceutical contaminants in water ecosystem, which cannot be removed efficiently by traditional techniques. Degradation of CBZ by peroxymonosulfate (PMS) activated with organo-montmorillonite supported nCoFe2O4 (nCoFe2O4/OMt) was investigated in this study. The degradation efficiency of CBZ (5 mg L−1) was 93% within 60 min in the presence of 0.4 g L−1 nCoFe2O4/OMt and 0.5 mM PMS at pH 6.8 and 25 °C, following a pseudo-first order kinetics. High PMS concentration and low initial pH could enhance CBZ degradation. The presence of Cl−, NO3− and HCO3− showed marked enhancement, slight suppression and obvious inhibition of CBZ degradation, respectively. High concentration of humic acid could decrease the CBZ degradation. X-ray photoelectron spectroscopy of nCoFe2O4/OMt before and after reaction revealed that both Co2+/Co3+ and Fe2+/Fe3+ were involved in PMS activation during the CBZ degradation. Electron paramagnetic resonance and radical scavenger experiments confirmed that both OH and SO4− played a predominant role on the CBZ degradation. The degradation products were identified by LC–MS/MS to understand the possible pathways.