Trametes versicolor laccase immobilized poly(glycidyl methacrylate) based cryogels for phenol degradation from aqueous media

This study aims removal of phenols in wastewater by enzymatic oxidation method. In this study, Trametes versicolor laccase was covalently immobilized onto a cryogel matrix by the nucleophilic attack of amino groups of laccase to epoxy groups of matrix. Glycidyl methacrylate was chosen as functional monomer to prepare poly(2-hydroxyethyl methacrylate-co-glycidyl methacrylate) [p(HEMA-co-GMA)] cryogels. The enzyme immobilized matrix was characterized by FTIR, SEM, and swelling tests. The effect of pH, reaction time, temperature, substrate concentration, enzyme concentration, and storage period on immobilized enzyme activity was determined and compared with those of free enzyme. The model substrate was 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid (ABTS). Lineweaver-Burk plots were used to calculate Km and Vm values. Km values were 165.1 and 156.0 µM while Vm values were 55.2 µM min−1 and 1.57 µM min−1 for free and immobilized laccase, respectively. Immobilized enzyme was determined to retain 82.5% and 72.0% of the original activity, respectively, after 6 consecutive use and storage period of 4 weeks. The free enzyme retained only 24.0% of its original activity following the same storage period. Lastly, decomposition products resulting from enzymatic oxidation of a model phenolic compound (3,5-dinitrosalicylic acid) in aqueous solution were identified by liquid chromatography-tandem mass spectrometry (LC-MS/MS). © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41981.