Optimisation of soybean peroxidase treatment of 2,4-dichlorophenol

Abstract

In the presence of hydrogen peroxide (H2O2), peroxidase enzymes (PE) catalyse the oxidation of various chlorinated phenols to free radicals, which then combine to form insoluble polymers that precipitate out of solution. This study systematically characterises the treatment of 2,4-dichlorophenol (2,4-DCP) using soybean peroxidase (SBP) as an oxidising catalyst. The effects of pH, SBP concentration, polyethylene glycol (PEG) additive and initial chlorophenol concentration on 2,4-DCP treatments are reported. Optimum pH for removal of 2,4-DCP without PEG was pH 8.2. The pH operating range of SBP was from 2.5 to 9.4 which is wider than reported for horseradish peroxidase (HRP). A general equation is presented that describes the units of SBP required (without PEG) to treat a given amount of 2,4-DCP at the optimum pH of 8.2. Addition of PEG increased the effectiveness of SBP by factors of 10 and 50 for PEG-3350 and PEG-8000 respectively. A new pH optimum of 6.2 was also found when SBP was used with PEG.

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