Laccase was immobilized on the ceramic-chitosan composite support by using glutaraldehyde as the cross-linking reagent. The immobilization conditions and characterization of the immobilized enzyme were investigated. T...Laccase was immobilized on the ceramic-chitosan composite support by using glutaraldehyde as the cross-linking reagent. The immobilization conditions and characterization of the immobilized enzyme were investigated. The immobilization of laccase was successfully realized when 3.0 mL of 1.25 mg/mL of laccase at a pH value of 4.0 reacted with 0.15 g of ceramic-chitosan composite support(CCCS) at 4 ℃ for 24 h. The immobilized enzyme exhibited a maximum activity at pH 3.0. The optimal temperatures for immobilized enzyme were 25 ℃ and 50 ℃. The K_m value of immobilized laccase for ABTS was 66.64 μmol/L at a pH value of 3.0 at 25 ℃. Compared with free laccase, the thermal, operating and storage stability of immobilized laccase was improved after the immobilization.展开更多
The immobilization of pre-dispersed Ti O2 colloids onto the external surface of the clay mineral montmorillonite（Mt） was accomplished and regulated via a self-assembly method employing the cationic surfactant cetylt...The immobilization of pre-dispersed Ti O2 colloids onto the external surface of the clay mineral montmorillonite（Mt） was accomplished and regulated via a self-assembly method employing the cationic surfactant cetyltrimethylammonium bromide（CTAB）. The role of CTAB in the synthesis process was investigated by preparing a series of Ti O2-CTAB-Mt composites（TCM） with various CTAB doses. The results indicated that a uniform and continuous Ti O2 film was deposited on the external surface of montmorillonite in the composite synthesized with 0.1 wt.% of CTAB, and the TCM nano-composites showed much higher values for specific surface area, average pore size and pore volume than the raw montmorillonite clay. Then, the formed TCM materials were applied in photocatalytic degradation of 2,4-dichlorophenol（2,4-DCP） in aqueous solution. The degradation efficiency reached as high as 94.7%. Based on the degradation intermediates benezoquinone, fumaric acid and oxalic acid identified by LC-MS analysis, a mechanism for the photocatalytic oxidation of 2,4-DCP on Ti O2/Mt nano-composites is proposed.展开更多
文摘Laccase was immobilized on the ceramic-chitosan composite support by using glutaraldehyde as the cross-linking reagent. The immobilization conditions and characterization of the immobilized enzyme were investigated. The immobilization of laccase was successfully realized when 3.0 mL of 1.25 mg/mL of laccase at a pH value of 4.0 reacted with 0.15 g of ceramic-chitosan composite support(CCCS) at 4 ℃ for 24 h. The immobilized enzyme exhibited a maximum activity at pH 3.0. The optimal temperatures for immobilized enzyme were 25 ℃ and 50 ℃. The K_m value of immobilized laccase for ABTS was 66.64 μmol/L at a pH value of 3.0 at 25 ℃. Compared with free laccase, the thermal, operating and storage stability of immobilized laccase was improved after the immobilization.
基金financially supported by the National Natural Science Foundation of China (No. 21207003)the Fundamental Research Funds for the Central Universities (ZY1302)the special fund of State Key Joint Laboratory of Environment Simulation and Pollution Control (No. 13K08ESPCT)
文摘The immobilization of pre-dispersed Ti O2 colloids onto the external surface of the clay mineral montmorillonite（Mt） was accomplished and regulated via a self-assembly method employing the cationic surfactant cetyltrimethylammonium bromide（CTAB）. The role of CTAB in the synthesis process was investigated by preparing a series of Ti O2-CTAB-Mt composites（TCM） with various CTAB doses. The results indicated that a uniform and continuous Ti O2 film was deposited on the external surface of montmorillonite in the composite synthesized with 0.1 wt.% of CTAB, and the TCM nano-composites showed much higher values for specific surface area, average pore size and pore volume than the raw montmorillonite clay. Then, the formed TCM materials were applied in photocatalytic degradation of 2,4-dichlorophenol（2,4-DCP） in aqueous solution. The degradation efficiency reached as high as 94.7%. Based on the degradation intermediates benezoquinone, fumaric acid and oxalic acid identified by LC-MS analysis, a mechanism for the photocatalytic oxidation of 2,4-DCP on Ti O2/Mt nano-composites is proposed.
