Degradation of bisphenol A through transition metals activating persulfate process

Abstract

In this study, the process of transition metals (Fe2+, Fe0, Ni2O3) activating persulfate was attempted to degrade aqueous bisphonel A (BPA). Compared with thermal activation mode, significant degradation can be achieved at normal atmospheric temperature in transition metal activation mode. BPA removal in the transition metal-PS system can be divided into rapid phase (0–5 min) and slow phase (5–60 min). In rapid phase, 87.71% and 90.60% removal efficiencies were obtained in the Fe2+-PS and Ni2O3-PS systems, and the contaminant was almost completely oxidized after 60 min. There are many similarities between the Fe2+-PS and Fe0-PS systems, in particular the optimal removal efficiencies were achieved at n0(Fe2+):n0(PS) = 1:2 and n0(Fe0):n0(PS) = 1:2 rather than with maximum metal dosage. The Ni2O3 dosage had positive correlation with BPA removal rate while the degradation efficiency of the Fe2+-PS system could be promoted by keeping n0(sodium citrate):n0(Fe2+) below 1:1. Intermediate products of the Fe2+-PS system were analyzed by LC-MS and were predominantly phenol, p-hydroxyacetophenone, benzoquinone and propanedioic acid, therefore a possible oxidation degradation pathway was speculated.