Natural-based hydrogels enriched with immobilized enzymes for wastewater treatment

Abstract

Conventional wastewater treatment systems often have limitations in effectively removing recalcitrant pollutants, including dyes, pharmaceuticals, toxic industrial chemicals, etc., posing severe health and environmental risks, and necessitating efficient and eco-friendly alternatives. Utilizing biological systems such as enzyme-based treatment presents a viable alternative for removing these compounds but often suffers low stability, leaching, and mass transfer limitations, hindering real world scalability. This project seeks to produce an efficient, sustainable and eco-friendly laccase-immobilized hydrogel biocomposite from natural sources, for enhanced degradation of selected dyes and non-chromophoric phenolic pollutants. The study emphasizes the development of novel hybrid carrier system for enzyme immobilization to obtain a synergistic improvement of laccase degradation action. Characterization by FTIR analysis confirmed successful immobilization of laccase, whereas spectrophotometric analysis comprehensively evaluated catalytic performance, thermal response, operational stability, storage stability, leaching behavior and reusability of obtained heterogenous biocatalyst. Glutaraldehyde-crosslinked biocomposite retained >90% activity after 5 reaction cycles performed with ABTS as the substrate, demonstrated 94.8% and 90.7% decolorization efficiency for the selected dyes, as well as exhibited superior stability over native/free form of laccase. However, in case of phenolic compounds, severe enzyme inactivation was observed due to irreversible adsorption of oxidative byproducts. The results highlight the potential of the biocomposite for effective dye decolorization and future strategies for improving stability against complex phenolic pollutants.