Immobilization Of Lipase By Inorganic Carrier And Its Application In The Production Of Biodiesel

In this thesis, we successfully prepared gluconic acid modified magnetic particles andcarbon-based materials to immobilized lipase. Because of big surface area and rich functionalgroups, the lipase could coat on their surface. The stability and reusability of lipase wereimproved after immobilized. We try to explore a novel enzyme immobilization technologywhich can enhance the thermal stability, recycling, activity of immobilized enzyme andprovide a new kind of heat-resistant, efficient, expeditious, stable carriers, and technologiesfor biodiesel.The results showed that:1. The magnetic Fe3O4nanoparticles were synthesized by coprecipitation method. Thesurface modified Fe3O4nanoparticles were characterized by SEM、XRD and FT-IR. Particlesize of magnetic Fe3O4nanoparticles were well distributed and showed good monodispersity,the functional groups can also be found after modification.2. In addition, lipase was successfully immobilized on the surface of gluconic acidmodified Fe3O4nanoparticles by chemical covalent. We tested the thermal stability, the pHstability, the repeated use of activity and storage stability of the immobilized lipase and thefree enzyme. Experiments can be drawn: compared with the free enzyme, a variety ofoperational stability of immobilized enzyme were substantially increased.3. Functional carbon-based materials were synthesized by hydrothermal synthesis usingcorncob as raw materials. The influence of different kinds and concentrations of inorganicacids such as phosphoric acid, hydrochloric acid, sulfuric acid for the preparation offunctional carbon-based materials were investigated. The results showed that there wereabundant functional groups on carbon surface when add inorganic acids in the reactionsystem.4. Lipase was immobilized on functional carbon materials. Compared with the freeenzyme, the thermal stability, pH stability, the activity of repeat and storage stability ofimmobilized lipase were increased.5. The thermal stability, pH stability, reuse, and storage stability of the immobilizedenzyme catalyzed preparation of biodiesel were investigated. The results showed that: immobilized enzyme showed high catalytic activity and stability in the biodiesel process, so itwill have a broad research and application prospects in preparation of biodiesel.6. The transesterification by immobilized lipase catalyst was investigated. The resultsshowed that optimum reaction parameters of soybean oil catalyzed synthesis of biodiesel asfollows: three times to add methanol,20%of the immobilized enzyme, methanol to oil ratio is3:1,20%water content, n-hexane as solvent, the reaction temperature of40°C; in thiscondition, the reaction for12h, the highest yield of methyl ester up to70%. Metal ions had aninsignificant effect on the immobilized enzyme.