Removal of bisphenol A from acidic sulfate medium and urban wastewater using persulfate activated with electroregenerated Fe2+

Abstract

Model solutions of bisphenol A (BPA) in 0.050 M Na2SO4 at pH 3.0 have been treated by the electro/Fe2+/persulfate process. The activation of 5.0 mM persulfate with 0.20 mM Fe2+ yielded a mixture of sulfate radical anion (SO4*- ) and * OH, although quenching tests revealed the prevalence of the former species as the main oxidizing agent. In trials run in an IrO2/carbon-felt cell, 98.4% degradation was achieved alongside 61.8% mineralization. The energy consumption was 253.9 kWh (kg TOC) -1, becoming more cost-effective as compared to cells with boron-doped diamond and Pt anodes. Carbon felt outperformed stainless steel as cathode because of the faster Fe2+ regeneration. All BPA concentration decays agreed with a pseudo-fist-order kinetics. The effect of persulfate, Fe2+ and BPA concentrations as well as of the applied current on the degradation process was assessed. Two dehydroxylated and three hydroxylated monobenzenic by-products appeared upon SO4*- and * OH attack, respectively. The analogous treatment of BPA spiked into urban wastewater yielded a faster degradation and mineralization due to the cogeneration of HClO and the larger *OH production as SO4*- reacted with Cl- .