Amino-functionalized cellulose beads supporting laccase: A dual-function catalyst for simultaneous adsorption and enzymatic conversion of tetracycline

In this study, a novel cellulose-derived support of amino-functionalized cellulose beads (ACBs) for laccase immobilization was successfully developed using cellulose beads (CBs) and polyethyleneimine by glutaraldehyde crosslinking reaction. The covalent immobilization of laccase on ACBs was achieved via a Schiff base reaction. The obtained enzyme catalysts (Lac-ACBs) were applied for simultaneous adsorption and enzymatic conversion of tetracycline (TC) from water. The structure and properties of all samples were characterized by SEM-EDS, FT-IR, XRD, BET, and EA. Furthermore, the Lac-ACBs exhibited excellent stability and reusability: after 15 cycles of catalysis, they maintained 72 % of their original activity. The Lac-ACBs were applied for the removal of TC from water with simultaneous adsorption and enzymatic conversion, achieving an 82 % removal efficiency. The enzymatic conversion products were examined to investigate the mechanism of the conversion. The data illustrated that oxidation, dehydrogenation, and demethylation are major reactions in that process.