介孔SiO2/Fe3O4中空磁性微球的漆酶固定化

以介孔SiO2/Fe3O4磁性中空微球作为载体,采用物理吸附法对漆酶进行固定化,考察了时间、温度和pH值对漆酶固定化效果的影响,并对固定漆酶的活性及稳定性进行了研究.结果表明,介孔SiO2/Fe3O4磁性中空微球吸附漆酶分子后,介孔材料的比表面积与孔体积均减小.在3 h时复合微球对漆酶的吸附达到平衡,复合微球中介孔SiO2对漆酶的有效固定量为689 mg/g,大大高于纯介孔材料MCM-41的漆酶固定量(319 mg/g).在pH=3～6的条件下,复合微球中固定漆酶仍保持70%以上的相对酶活.当温度不高于60℃时,固定漆酶的相对酶活仍保持65%以上.固定漆酶的pH稳定性和热稳定性都明显优于游离漆酶,固定漆酶的米氏常数为1.05 mmol/L,与游离漆酶相比,固定漆酶与底物的亲和力有所降低.当2,4-二氯苯酚的浓度为10 mg/L时,固定漆酶对其去除率在6 h时达到81.6%,表现出很好的催化活性.

Studies on Laccase Immobilization of Mesoporous SiO2/Fe3O4 Hollow Microspheres

Mesoporous SiO2/Fe3O4 hollow microspheres were used to immobilize laccase with a physical adsorption method. The influence of some experimental factors, such as adsorption time, temperature and pH value on laccase immobilization were investigated. The pH stability and temperature stability of the immobilized laccase were also studied under different conditions through researching its residual catalytic activity. The surface area(772 m2/g) and pore volume(0.83 cm3/g) of the mesoporous SiO2/Fe3O4 hollow microspheres decrease to 390 m2/g and 0.66 cm3/g, respectively, after laccase was immobilized on the composite microspheres. The immobilization amount of laccase in the mesoporous silica in mesoporous SiO2/Fe3O4 microspheres is 689 mg/g, which is higher than that in MCM-41(320 mg/g). The residual catalytic activities of the immobilized laccase at pH=3～6 and 60 ℃ remains higner than 80% and 60%, respectively. The immobilized laccase keeps a more stable catalytic activity than free laccase. The Michaelis constant of immobilized laccase is 1.046 mmol/L. The affinity of the immobilized laccase to its substrate declines slightly compared to free laccase. The immobilized laccase also exhibits an excellent catalytic performance in the removal of 2,4-dichlorophenol.