Catalytic degradation of diethyl phthalate in aqueous solution by persulfate activated with nano-scaled magnetic CuFe2O4/MWCNTs

Abstract

Diethyl phthalate (DEP), a plasticizer widely used in chemical industry, has been classified as an endocrine disruptor. Therefore, it is urgent to develop methods for degradation of DEP to minimize its ecological risk. In this study, copper ferrite decorated multi-walled carbon nanotubes magnetic nanoparticles (CuFe2O4/MWCNTs MNPs) were prepared by sol–gel combustion method as catalysts for the degradation of DEP. The catalysts were characterized by scanning electron microscope, transmission electron microscope, Fourier transform infrared spectroscopy, nitrogen gas uptake, X-ray diffraction, and X-ray photoelectron spectroscopy. Catalytic degradation of DEP by persulfate (PS) was investigated with various influencing factors including catalyst loading, PS concentrations, temperature and pH. Furthermore, the CuFe2O4/MWCNTs MNPs showed high catalytic activity, stability and recyclability in DEP removal. Especially, leaching of metal ions from reused CuFe2O4/MWCNTs was negligible (concentration<0.4%), indicating the resistance to oxidation. The electron paramagnetic resonance analysis confirmed that the addition of CuFe2O4/MWCNTs into PS system can accelerate the generation of OH and SO4−, and the quenching experiments further certified the catalytic reaction was predominated by SO4−. The degradation intermediates were identified and the pathways were proposed. Overall, this study provides practical knowledge for DEP removal by CuFe2O4/MWCNTs activated PS at ambient temperature.