KAOLIN AS A SUPPORT FOR THE IMMOBILIZATION OF HORSERADISH PEROXIDASE: APPLICATION IN ANTHRAQUINONIC DYES DECOLORIZATION FROM WASTEWATER

Abstract

The world is facing with global water crisis because around 20 % of untreated or partially treated wastewater is discharged directly into the environment. The main objective of this paper was to develop an eco-friendly, sustainable biocatalyst for the decolorization of wastewater from different industries colored with anthraquinonic dyes. Anthraquinonic dyes have fused aromatic rings, which makes them extremely stabile against photolytic degradation as well as microbial attack. They are synthesized from antracene, toluene, benzidine so their brakedown products are toxic, muthagenic, carcinogenic. Natural clay, kaolin was used as a support for the immobilization of horseradish peroxidase. Prior to immobilization kaolin was activated with different concentrations of glutaraldehyde (0.1-1%). Next, concentration of the enzyme was varied in the range 0.5-5 mg cm-3 , and the maximum loading of 2.19 mg g-1 was obtained. The efficiency of the attained biocatalyst was examined in the reaction with model dye C. I. Acid Violet 109. Under defined conditions more than 90 % of the dye was removed within 40 min. Immobilized HRP approved as a much more stable in a wider pH range than free HRP. Besides, inhibitory influence of peroxide and dye after immobilization was reduced significantly. Furthermore, immobilized HRP exhibited reasonable reusability during the decolorization of tested anthraquinonic dye.