PHENOL REMOVAL FROM WASTEWATER USING HORSERADISH PEROXIDASE IMMOBILIZED ONTO MULTI-WALLED CARBON NANOTUBES VIA GLUTARALDEHYDE

Abstract

Phenolic components present in industrial wastewaters could negatively affect the aquatic ecosystem and human health if they are not properly treated before discharge into waterways. The treatment that can effectively remove phenol from water is a biological process using peroxidases. In the presence of hydrogen peroxide, peroxidases lead to the polymerization of phenol, whereby the resulting polymers are precipitated and thus separated from the water. A significant advantage is achieved when peroxidases are used in an immobilized form on a suitable solid support. In addition to enabling its reuse in several consecutive cycles; the immobilized enzyme is significantly more stable compared to the free enzyme. In this paper, the effectiveness of the application of immobilized horseradish peroxidase onto surface modified carbon nanotubes in the removal of phenol from wastewater was examined. Carbon nanotubes were functionalized with concentrated nitric acid and used as solid support for peroxidase immobilization via glutaraldehyde. A phenol solution in ultra-pure deionized water was used as a model of phenol-containing wastewater. Using immobilized horseradish peroxidase (0.6 U/ml), 82% of phenol was removed after 2 hours of reaction. It can be concluded that bio-catalytic treatment of phenolic wastewater can significantly reduce the content of phenolic pollutants.