Experimental and Theoretical Study on the Transformation Behavior of Bisphenol S by Radicals Driven Persulfate Oxidation

Abstract

An in-depth study on the degradation of bisphenol S (BPS) by both single-walled carbon nanotubes and heat activated persulfate (PS) was investigated in detail. The factors like materials dosage, initial substrate concentration, initial pH and water matrix on removal of BPS were evaluated and 10 µM BPS could be completely removed in 90 min under the optimal conditions of [BPS]0: [PS]0 = 1: 100, T = 25 ℃, pH0 = 7.0, [N-SWCNTs] = 20 mg·L− 1. Fast removal of BPS was also obtained when reaction temperature reached 65 ℃ without catalyst. There were 15 intermediates identified in total; and hydroxylation, sulfate addition, carboxylation, the cleavage of S − C bond and polymerization were considered as the main transformation pathways of BPS in both two systems based on LC-MS analysis. The proportion discrepancy of •OH and SO4•− involved in two systems led to different distribution and abundance of observed products. The results of transition state calculation further confirmed the reaction potential of hydroxylation, hydrogen atom abstraction and sulfate addition, and the minimum reaction barriers were 22.20, 25.06 and 13.85 kJ/mol, respectively. The present work firstly reveals the overall transformation behavior of BPS in radicals-triggered PS system by combining experimental and theoretical study.