Effective degradation of azo dyes by ABTS (2,2’-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid)) mediated laccase. Kinetic studies

Abstract

Laccases are enzymes with low substrate specificity that in certain cases require the presence of a mediator in order to work properly. Therefore, this paper investigated the degradation of Orange G, Ponceau 4 R and Methyl Red in the presence of laccase isolated from Trametes versicolor and laccase-ABTS system. Laccase, in high concentration, was able to oxidize only Orange G and Ponceau 4 R, with a degree of decolorization less than 10 % in 20 min. In the presence of laccase-ABTS system, the reaction is much faster, and at least 40 % of dyes were degraded in 15 min. A kinetic model accounting for enzymatic oxidation of all dyes, including a step for enzyme operational inactivation, was proposed. This study proves that we can use a single kinetic model for the oxidation of all dyes in the laccase-ABTS system.