New life of waste material: immobilized horseradish peroxidase for degradation of antraquinone dye

Abstract

Various strategies have been developed for the removal of synthetic dyes from the wastewater of the textile industry due to their stability as well as their negative effect on the environment. Enzymatic wastewater treatments as environmentally safe processes have many benefits. An enzyme suitable for use in the treatment of wastewater from the textile industry is horseradish peroxidase (HRP) because it can degrade different types of dyes. Immobilized enzymes have many advantages over free enzymes in solution such as higher stability and the opportunity to be removed easily from the reaction mixtures. Consequently, immobilized enzymes can be used more than once. Many different materials are used as a carrier for enzyme immobilization, so if residual material is used as a carrier, waste valorization will be achieved. In this study immobilized commercial HRP was used for decolorization of anthraquinone dye Acid green 40 (AG 40). Waste material – potato peels were used as a carrier for the immobilization of HRP. Potato peels were oxidized with sodium periodate to introduce aldehyde groups that can react with the primary amino groups of the enzyme to form Schiff bases, resulting in covalently immobilized HRP. The success of the oxidation was verified by the 2,4-dinitrophenylhydrazine (DNPH) test, and subsequently, the oxidized potato peels were characterized by SEM and FTIR. After oxidation, the influence of the mass of the immobilization carrier on enzyme activity and immobilization efficiency was investigated. The optimal conditions of pH, hydrogen peroxide concentration, concentration of AG 40, and enzyme activity were determined for decolorization of AG 40 with immobilized HRP. Adsorption of AG 40 on the carrier was also determined. In addition, the operational stability of the enzyme was determined. The results obtained show that oxidized potato peels are a promising material that can be used as a carrier for the immobilization of HRP.