Abstract
The removal of synthetic dyes from textile wastewater is a critical environmental challenge. This study investigates the performance of chitosan-based materials, including plain chitosan, magnetic chitosan, and magnetic chitosan immobilized with laccase, for the removal of three representative textile dyes: Methylene Blue (MB), Bromophenol Blue (BPB), and Coomassie Brilliant Blue (CBB). The adsorption of dyes onto plain chitosan was strongly pH-dependent, governed by electrostatic interactions between dye molecules and chitosan functional groups. Increasing pH enhanced MB adsorption, while reducing the uptake of the anionic dyes BPB and CBB. Incorporation of iron oxide nanoparticles significantly improved adsorption capacity by increasing surface area and introducing additional interaction mechanisms. Further enhancement was achieved through laccase immobilization, which increased dye removal at all investigated pH values, with the most pronounced effect under acidic conditions (pH 5.0–7.0), consistent with the optimal catalytic activity of the enzyme. Reusability tests demonstrated good operational stability, with approximately 60% of the initial dye removal efficiency retained after 12 cycles, highlighting the potential of this system for sustainable textile wastewater remediation.
