Degradation of bisphenol A through transition metals activating persulfate process

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.