Manganese Peroxidase-Catalyzed Treatment of Aqueous Chlorophenols

Abstract

Chlorophenols (CPs) are recalcitrant priority pollutants commonly detected in industrial effluents due to their widespread use in agrochemical, pharmaceutical, and materials manufacturing. Their persistence, toxicity, and resistance to conventional biological treatment necessitate the development of sustainable remediation strategies. This study evaluates the feasibility of manganese peroxidase- (MnP)-catalyzed treatment for the removal of aqueous 2-chlorophenol (2-CP), 3-chlorophenol (3-CP), 4-chlorophenol (4-CP), and 2,4-dichlorophenol (2,4-DCP) under ambient conditions. Batch reactions were conducted at pH 4.5 in the presence of Mn(II) and hydrogen peroxide, with systematic optimization of enzyme activity and oxidant addition strategy. Stepwise addition of H2O2 was found to preserve catalytic activity and significantly enhance substrate removal compared to single-aliquot addition. Under optimized conditions, removal efficiencies ≥90% were achieved for 2-CP, 4-CP, and 2,4-DCP within 60 minutes, whereas 3-CP exhibited markedly lower efficiency. First-order kinetic analysis confirmed compound-dependent initial conversion rates. Liquid chromatography–high resolution mass spectrometry revealed the formation of higher-order oligomers (up to decamers), supporting a radical-mediated oligomerization–precipitation pathway accompanied by partial dechlorination. These findings demonstrate that MnP, via product of heterologous expression in corn, can effectively transform chlorophenols into readily separated insoluble polymeric products, offering an environmentally compatible and potentially cost-effective alternative to conventional physicochemical treatment methods for chlorophenol contaminated wastewater.