Degradation of 2,4-dichlorophenols catalyzed by laccase immobilized on chitosan

Research on the removal of 2,4-DCP in aqueous solution by laccase immobilized on chitosan was carried out. Factors, such as pH value, temperature and adsorption on support that could influence the oxidation were discussed in detail compared with free laccase. The results indicated that the optimal pH for 2,4-DCP removal by immobilized laccase was around 5.5, lower than the free enzyme for pH 6.0. The optimum temperature of immobilized laccase was between 35??C and 45??C, wider than the free enzyme. Adsorption of chlorophenol on support had a little effect on the degradation reaction and removal rates of chlorophenols, and the decrease of chlorophenols levels was resulted from catalyzeing for laccase. The continuous oxidation of 2,4-DCP, carried out in the static system of immobilized laccase, showed that the removal efficiency of immobilized laccase still remained over 60% after 6 cycles of operation. Thus the catalytic efficiency of laccase was greatly improved.EI04484-4894