A NEW METHOD TO REMOVE PENTACHLOROPHENOL CATALYTICALLY IN WASTEWATER BY IMMOBILIZED HORSERADISH PEROXIDASE

摘要

A new technique that horseradish peroxidase (HRP) immobilized on the carrier of Fe_3O_4 adsorption and gelatin embedding was applied to catalyze the removal of pentachlorophenol (PCP), one of organic chlorine pesticides. Experiments were carried out to determine the optimal reaction conditions: The dosage ratio of HRP: Fe_3O_4: gelatin was 95 U: 1.0 g: 10 mL (10-20%); the concentration of glutaraldehyde was 0.5%; the cross-linking time was 30 minutes. Under these conditions, the enzymatic activity of immobilized HRP was 1.1 Ug~(-1) (wet weight). The removal efficiencies of PCP by immobilized HRP and free HRP were compared. The reaction equilibrium was achieved in average 30 min, but immobilized HRP saw a broader pH range (4-6) with higher maximum removal efficiency (41% at pH 5) and a lower K_m compared with free HRP. The amount of PCP removed by immobilized HRP increased with the initial concentration of PCP rising, although the removal efficiency decreased from 39.7% to 24.4%. The percentage of removed PCP remained>39% when HRP (0.05 U-mL~(-1)) was used repeatedly for 7 rounds. This work provided a method for further studies to deal with endocrine-disrupting chemicals in wastewater.