Bioremediation of multifarious pollutants using laccase immobilized on magnetized and carbonyldiimidazole-functionalized cellulose nanofibers

An easily recyclable biocatalyst (Lac@CDI-MCNFs) was synthesized by immobilizing laccase on rice straw-derived carbonyldiimidazole mediated magnetized cellulose nanofibers (MCNFs). Lac@CDI-MCNFs were utilized for bioremediation of cefixime antibiotic (CT), carbofuran pesticide (CF) and safranin O dye (SO) via oxidation-reduction reactions in wastewater. MCNFs provided enhanced pH, temperature and storage stability to laccase and allowed reusability for up to 25 cycles with mere 20 % decline in efficacy. The Lac@CDI-MCNFs effectively degraded 98.2 % CT and 96.8 % CF into benign metabolites within 20 h and completely degraded SO in just 7 h. Response surface modelling (RSM) was employed based on the Box Behnken Design to evaluate the effect of various parameters i.e. pH, catalyst dosage and the pollutants concentration which was further validated with experimental studies. The degradation products were identified using LCMS, which allowed the degradation pathway of the pollutants to be determined. The degradation of all pollutants followed first- order kinetics with rate constants of 0.1775, 0.0832 and 0.958 h −1 and half-life of 3.9, 5.0 and 0.723 h for CT, CF and SO, respectively. Lac@CDI-MCNFs was demonstrated to be an effective catalyst for the degradation of multifarious pollutants.