The Immobilization of Laccase on Mixed Polymeric Microspheres for Methyl Red Decomposition

Abstract

Means of eliminating water pollutants or transforming them into less hazardous compounds by green catalysis are desired. The current work was developed with the goal of discovering supports suited for laccase (Lc) immobilization. The effect of the chitosan (CS) molecular weight (Mw) or the polyacrylic acid (PAA) addition was evaluated in microsphere formulation and enzyme immobilization by ESEM, rheology, operational stability, and kinetics. As a practical application, the synthesized products were tested in the methyl red (MR) decomposition and the product identification was performed by high-resolution mass spectrometry. Depending on the required properties, the laccase activity profile (pH, temperature, storage, and Michaelis–Menten parameters) and rheological strength can be modulated by varying the molecular mass of CS or by adding PAA in the support formulation. The immobilized products having the best features regarding MR degradation and recycling abilities were the medium Mw CS microspheres and the system with low Mw CS complexed by PAA, respectively. The degradation mechanism of the dye was proposed accordingly with the identified products by mass spectroscopy. The findings emphasize the potential of the proposed immobilization products to be exploited as viable biocatalysts for dye-contaminated water.