Bisphenol A degradation in aqueous solutions by electrogenerated ferrous ion activated ozone, hydrogen peroxide and persulfate: Applying low current density for oxidation mechanism

Bisphenol A (BPA) is an ubiquitous environmental contaminant which is categorized as an endocrine disruptor compound. In this study, BPA was removed using electrogenerated ferrous ion (EC) activated ozone, hydrogen peroxide (HP) and persulfate (PS). The effects of operating parameters such as pH, current density, oxidant dosage and time, were evaluated on three systems of EC/HP, EC/PS and EC/ozone. The acidic condition (pH = 3.0-5.0) was suitable for all the processes. The results showed that EC/ozone had the best performance in degradation of BPA compared to others. Moreover, the presence of chloride was investigated in three systems and the related results displayed a slight increase in removal efficiency. Electrochemical degradation of BPA in a divided cell proved that ozone was activated by both anode and cathode reactions while HP and PS were activated only in anode compartments endorsing HP and PS catalytic activation by ferrous ion. In addition, the reaction mechanism demonstrated that sulfate radical was the major oxidant in EC/PS while hydroxyl radical was the main agent in EC/HP and EC/ozone systems. However, the results indicated that ozone can solely degrade BPA significantly in comparison with other oxidants. The synergistic effects along with kinetic model were also assessed for all the processes. The mineralization was studied by total organic carbon (TOC) and the order of TOC removal was EC/ozone > EC/HP > EC/PS > ozone > EC > PS > HP. The electrochemical sludge generated was reused for activation of the oxidants as HP and PS were noticeably activated while no effect was observed on ozone application. (C) 2016 Elsevier B.V. All rights reserved.