Study On Preparation Of The Composite Microspheres And Their Application For Immobilized Lipase

The technology of immobilization enzyme have been developing fast since 1960s. In the recent decades, research on usable immobilization carriers has been focused much attention in this field. The performance of immobilized enzyme depended on the properties and immobilized method of the enzyme carrier material. In this paper, the immobilization methods, properties and usage of immobilized enzyme were introduced, and then two kinds of carriers were designed and prepared. They were employed in immobilizing lipase. The carrier has a definite application prospect at the preparation of the biodiesel. The main contents for this thesis are listed as below:1. The composite microspheres were prepared by inverse emulsion crosslinking in oil-water emulsion of casein and chitosan. The properties of the composite microspheres were characterized by different techniques, such as SEM, DSC and FT-IR. The results indicate that the composite microspheres are some resistant to high temperature, acid and alkaline. And the particle size is homogeneous.2. Fe₃O₄ nanoparticles were synthesized by the chemical co-precipitation, the average diameter and saturation magnetization were found to be 18 nm and 69.0 emu/g respectively.3. The magnetic composite microspheres were prepared by inverse emulsion crosslinking in oil-water emulsion of casein, chitosan and Fe₃O₄ nanoparticles. The properties of the magnetic composite microspheres were characterized by SEM, DSC, FT-IR, XRD and VSM. The results indicate that the magnetic composite microspheres are strongly resistant to high temperature and the particle size is homogeneous. The satuation magnetization was found to be 24.5 emu/g carriers. There was no hysteresis in the magnetization with both remanence and coercivity being zero, and the composite microspheres can be separated from the reaction medium rapidly and easily in a magnetic field.4. Lipase was immobilized on composite microspheres by physical adsorption. The immobilization conditions were optimized. The themal stability and reusability of the immobilized lipase were also investigated. The results indicated that the recovery rate of immobilized lipase was 53%, the optimun pH and temperature of the immobilized lipase were 7.5 and 40℃. Compare to the free liapse, the immobilized lipase has a good thermal, adaptability and reusability.5. Lipase was immobilized on magnetic composite microspheres by physical adsorption. The immobilization conditions were optimized. The themal stability and reusability of the immobilized lipase were also investigated. The results indicated that the recovery rate of immobilized lipase was 57%, the optimun pH and temperature of the immobilized lipase were 8.0 and 50℃. Compare to the free liapse, the immobilized lipase has a good thermal, adaptability and reusability. Meanwhile, the immobilized lipase could be separated, recovered easily and rapidly.