Removal of phenanthrene and acenaphthene from aqueous solution by enzyme-catalyzed phenol coupling reaction

• HRP catalyzed phenol coupling could effectively remove PAHs from solution.
• Sorption and chemical incorporation in the polyphenols were the primary mechanisms.
• Sorption played a dominant role in the removal of phenanthrene.
• The incorporation in the polyphenols was the predominant pathway for acenaphthene.
• PAH removal was directly relate to the molar ratio of phenol to PAH.

Removal of phenanthrene and acenaphthene from aqueous solution was investigated using phenol coupling reaction catalyzed by horseradish peroxidase (HRP). The results revealed that HRP-catalyzed phenol coupling reaction could effectively reduce the concentration of phenanthrene and acenaphthene in the aqueous solution. The removal of phenanthrene and acenaphthene from solution results from sorption and chemical incorporation in the polyphenols formed by enzyme catalyzed phenol coupling reaction. Among these two removal pathways sorption played a dominant role in the removal of phenanthrene from water, whereas for acenaphthene the incorporation in the formed polyphenols was the predominant pathway. The removal efficiency of PAHs increased with increasing the molar ratio of phenol to PAH up to approximately 50–60, and decreased with increasing the molar ratio. Increasing sorption and incorporation of PAHs in the polyphenols manifested apparent aggregation and precipitation forming larger particles in aqueous solution. These results presented in this study provide a potential strategy for remediation of the sites co-contaminated with phenols and PAHs.

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