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

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 NO3-–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 OH 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.