Alginate-laccase beads in the decolourization of indigo carmine

Abstract

The aim of the study was to assess the feasibility of utilizing sodium alginate biopolymer as animmobilization carrier for laccase in the removal of indigo carmine (IC), an anionic dye. The main goal of this work was to optimize the decolourization process by selecting the appropriate immobilized enzyme dose per 1 mg of dye, as well as the process temperature. The effective immobilization of laccase using sodium alginate as a carrier was confirmed by Raman spectroscopy. An analysis of the size and geometric parameters of the alginate beads was also carried out. Tests of IC decolourization using alginate-laccase beads were conducted. Applying the most effective dose of the enzyme (320 mg of enzyme/1 mg of IC) made it possible to remove 92.5% of the dye over 40 days. The optimal temperature for the IC decolourization process, using laccase immobilized on sodium alginate, was established at 30-40ºC. The obtained results indicate that laccase from Trametes versicolor immobilized on sodium alginate was capable of decolourizing the tested dye primarily based on mechanism of biocatalysis.

Keywords

• immobilization;
• sodium alginate;
• indigo carmine;
• decolourization;
• laccase;