Effect of nitrate on the degradation of bisphenol A by UV/H₂O₂ and ozone/H₂O₂ oxidation in aqueous solution

Abstract

The goal of the present study was to investigate the effect of nitrate on the removal of bisphenol A (BPA) by conducting bench-scale UV/H₂O₂ and O₃/H₂O₂ operations under a variety of reaction time and initial concentrations of H₂O₂ and –N. Also, this study evaluated the advanced oxidation process processes and determined the optimal conditions, for removing BPA. The practical reaction time and initial H₂O₂ concentration for the more than 85% removal of BPA proved to be 2.0 min and 150 mg/L, respectively, in the presence or absence of nitrate. The removal efficiency of BPA was improved by the hydroxyl radicals produced from nitrate photolysis in the absence of H₂O₂. In the presence of H₂O₂, however, nitrate hindered the BPA removal by acting as scavengers under the operating conditions described above. Also, H₂O₂ acts as free-radicals scavenger at concentrations above optimum required. In O₃/H₂O₂ process with nitrate addition, more than 75% of the BPA was removed under the conditions of an initial O₃ concentration of 7.5 mg/L and H₂O₂ concentration of more than 150 mg/L.

Keywords:

• AOPs
• BPA
• Hydroxyl radical
• Nitrate
• Scavenger