Catalytic degradation of 2-phenylbenzimidazole-5-sulfonic acid by peroxymonosulfate activated with nitrogen and sulfur co-doped CNTs-COOH loaded CuFe2O4

Recently, the toxicity of sunscreen has received extensive attention due to their potential endocrine disrupting effect. In the present study, nitrogen and sulfur co-doped multi-walled carbon nanotubes loaded CuFe2O4 (NS-CNTs/CuFe2O4) catalyst was rationally designed and synthesized by co-precipitation method for the degradation of 2-phenylbenzimidazole-5-sulfonic acid (PBSA, a typical sunscreen addition). The catalyst was fully characterized by scanning electron microscope, transmission electron microscope, X-ray diffraction, Fourier transform infrared spectroscopy, nitrogen gas uptake, and X-ray photoelectron spectroscopy. Then the kinetics, pathways and mechanisms of catalytic degradation of PBSA were studied in NS-CNTs/CuFe2O4 activated peroxymonosulfate (PMS) solution. The catalyst showed high catalytic activity, stability and reusability in PBSA removal. The results of electron paramagnetic resonance (EPR) and quenching experiments suggested that sulfate radicals (SO4-) predominated in the activation of PMS by NS-CNTs/CuFe2O4. The synergistic effect between CuFe2O4 and NS-CNTs was proposed in PMS activation. In addition, eight degradation intermediates of PBSA were identified by liquid chromatography mass spectrometry (LC-MS), and degradation pathways were further proposed. Overall, this study provides insights of PBSA removal by NS-CNTs/CuFe2O4 activated PMS at ambient temperature. (C) 2016 Elsevier B.V. All rights reserved.