Redox-mediated polymerization and removal of benzidine from model wastewater catalyzed by immobilized peroxidase

Abstract

Peroxidase from Momordica charantia was highly effective, active and stable for the oxidation of benzidine from model wastewater. There was no oxidative polymerization of benzidine without any redox mediator. Various experimental parameters were standardized for the maximum oxidation of benzidine by peroxidase. The maximum oxidation of this pollutant was observed in the presence of 0.05 mM phenol, 0.75 mM H₂O₂ and 0.2 U mL^-1 bitter gourd peroxidase (BGP) in a buffer of pH 5.0 at 40°C. Comparative study was performed by soluble as well as surface immobilized bitter gourd peroxidase on Con A layered calcium alginate-starch beads for the degradation of benzidine from model wastewater. Immobilized bitter gourd peroxidase was used for the successful and effective removal of water polluted with benzidine in batch as well as in continuous reactor. The effect of detergents and some water miscible organic solvent was also reported for the oxidation of benzidine from polluted water. Oxidation of benzidine in batch process by soluble and immobilized peroxidase was highly effective and it could remove 72 and 100% benzidine by soluble and immobilized bitter gourd peroxidase, respectively. The reactor filled with immobilized enzyme retained more than 45% benzidine removal efficiency even after 30 days of its continuous operation. The absorption spectra of the treated benzidine exhibited a marked difference in absorption at its λ_max as compared to untreated benzidine polluted water.

Keywords: Alginate, bitter gourd peroxidase, concanavalin A, removal, immobilization