Microemulsion Based Organogel-Silica Composite as Feasible Matrix for Immobilization of Horseradish Peroxidase: Application to Oxidative Removal of Phenol from Aqueous System

摘要

The present work reports the immobilization of horseradish peroxidase (HRP) into microemulsion based organogel-silica composite material. The new matrix containing HRP was applied to oxidize phenol in aqueous solution in the presence of hydrogen peroxide (pH 7.5) using phosphate buffer. Characterization of the composite was carried out using SEM imaging/ mapping and FT-1R, which verified that the silica is well accumulated in the organogel network. The quantification of phenol in aqueous solutions was carried out using HPLC. Parameters influencing oxidation of phenol such as contact time, composite/enzyme amount, H2O3 concentration, stirring time and pH were optimized. The removal reached up to 99% when aqueous solution of phenol (10 mgl~(-1)) was heated with 150 mg organogel-silica composite containing 200 μg of entrapped enzyme and 1.8 ml of 1.0 mM H2O2 at pH 7.5. In addition to oxidation of phenol, it was found that benzoquinone formed in the reaction was removed by organogel-silica composite. The study concludes that HRP can be immobilized into organogel-silica composite with oxidation of phenolic substrate. The new matrix not only oxidizes phenol to muconic acid but also removes benzoquinone, a perilous byproduct in the catalytic oxidation of phenol in aqueous solutions.