Optimization of internal conditions for biocatalytic dye color removal and a comparison of redox mediatorʹs efficiency on partially purified Trichosanthes dioica peroxidase

The decolorization proficiency of partially purified Trichosanthes dioica peroxidase was examined for the degradation/decolorization of textile, non-textile dyes and dye mixtures. Internal conditions of pH, temperature, time intervals and enzyme concentration with selected redox mediator was optimized to obtain a cost effective decolorization setup for recalcitrant dyes. the tested redox mediators, 1-hydroxybenzotriazole (HOBT) acted as a better electron transfer agent by contrast to vanillin for both textile and non-textile dyes. Maximum decolorization for reactive and disperse dyes was achieved with optimum conditions of 0.45 EU/ml, 1.0 mM HOBT, pH 5.0, 50 °C, 2 h and 0.20 EU/ml, 0.2 mM HOBT, pH 4.0, 40 °C, 1 h, respectively. The dye color change was related to its structure and consequently reduction/oxidation mediated by HOBT. To study the performance of biocatalysis in a redox mediated heterogeneous system, dye mixtures simulating industrial effluents were used which exhibited more than 82% decolorization with 1-hydroxybenzotriazole. indicates the use of inexpensive peroxidase from easily available natural resources in overcoming the limitations in current wastewater treatment strategies. Such heterogeneous biocatalytic system can be extended on to large-scale treatment of wide spectrum of structurally complicated dyes by using immobilized peroxidases along with relatively cheaper redox mediators. A comparison of the efficiency with other redox mediators has also been discussed.