Removal of aqueous phenol and 2-chlorophenol with purified soybean peroxidase and raw soybean hulls

In this study, the removal of phenol and 2-chlorophenol using soybean seed-hulls in the presence of hydrogen peroxide is demonstrated. The performance of a stirred membrane reactor containing soluble purified SBP was compared with a batch stirred reactor containing raw soybean seed-hulls. The purified enzyme reactor proved to be ineffective while excellent results were obtained with the crude seed-hulls for the removal of phenol and 2-chlorophenol. Four sequential batch reactors containing raw seed-hulls achieved greater than 96% removal of phenol with a retention time of 20 min in each reactor. A single batch reactor containing raw seed-hulls was effective in removing greater than 98.5% of 2-chlorophenol (initially at 1000 ppm) in less than 15 min. The performance of these reactors is comparable to existing HRP-based technology. The stability of the soybean peroxidase (SBP) enzyme was also examined in the presence of detergents (SDS, Tween 20 and Triton X-100). Low concentrations of the detergents significantly increased the enzyme activity and higher concentrations of detergents (up to 20% w/v) did not inactivate the SBP enzyme. These results demonstrate that SBP has good potential for the treatment of phenol contaminated solutions.