Optimal conditions for oxidative degradation of bisphenol A by Horseradish Peroxidase in aqueous phase

Conditions for Horseradish Peroxidase (HRP) catalyzed oxidative degradation of bisphenol A (BPA) in wastewater were investigated in this research. The optimal pH and temperature for the oxidation of BPA catalyzed by HRP were pH 9.0 and 25°C respectively. The actual stoichiometry for the complete conversion of BPA was [H₂O₂]/[BPA] molar ratio of 1.5, higher than theoretic stoichiometry of 0.5 for this reaction. The probable explanation for this was that the degradation products, such as 4-isopropenylphenol and dimmer formed during the oxidation of BPA, could be oxidized by H₂O₂, which contributed to the total consumption of H₂O₂ for oxidation of BPA. The excessive initial H₂O₂ made HRP inactivity, which decreased the oxidation rate of BPA. In the primary reaction period, about 3 hours, the reaction was very quick at the certain level of HRP in the mixture. Near 80% of BPA was degraded in 3 h reaction period. But only 13.1% of original activity of HRP was kept after 5h reaction. It is necessary that further research be conducted to explore the possible method to keep the activity of HRP after finishing catalytic action for certain reaction.