Removal of Benzene from Wastewater by Enzyme-Catalyzed Oxidative Polymerization using Soybean Peroxidase Combined with a Modified Fenton Reaction

A two-step process for the removal of benzene from wastewater, pretreatment by modified Fenton reaction coupled with peroxidase-catalyzed polymerization of the resulting phenolic compounds, is presented. In the first step, the effect of pH, hydrogen peroxide and ferrous iron concentrations and reaction time for the Fenton reaction were studied to maximize the conversion of benzene to phenolic compounds without causing significant mineralization. Under optimum Fenton reaction conditions, conversion of benzene generated a mixture containing phenol, benzenediols, biphenyl and benzoquinone. In the second step, polymerization of the phenolic compounds was achieved by soybean peroxidase (SBP) in the presence of hydrogen peroxide. Factors of interest for the three-hour enzymatic step were pH, enzyme and hydrogen peroxide concentrations. Biphenyl and benzoquinone were outside the scope of enzymatic treatment. However, SBP was successful in removing the rest of the phenolic products under optimum conditions. Alum was used for color removal from the reaction mixture.