Treatment of aqueous pentachlorophenol by horseradish peroxidase and hydrogen peroxide

This study focused on the oxidation and subsequent polymerization and precipitation of pentachlorophenol (PCP) under the combined action of hydrogen peroxide and horseradish peroxidase (HRP). HRP was capable of catalyzing the oxidation and detoxification of 0.05 mmol PCP prepared in distilled/deionized water. The optimal pH for PCP transformation was in the range 4–5. PCP reacted with peroxide with a stoichiometry of 2:1. Stoichiometric and chloride production studies indicate that the main products generated in the PCP treatment process are dimers. The residual toxicities of treated solutions were higher than could be accounted for by residual PCP. It was concluded that unidentified soluble products contribute to this excess toxicity. In contrast to previous studies of the treatment of various phenols, neither polyethylene glycol nor chitosan were effective in reducing HRP dose requirements nor in enhancing toxicity removal during PCP treatment.