Degradation Of 2,4-dichlorophenol By Laccase Immobilized On Magnetic Nano And Mesoprous Materials

In this thesis, magnetic materials as carrier was used to the immobilize laccase, and then the immobilized laccase degrade 2,4-dichlorophenol. Magnetic particles include Fe3O4 particles and y-Fe2O3 particles. Because of their magnetic, catalytic and anisotropic properties, Fe3O4 particles and y-Fe2O3 particles are widely used in biomedical, environment fields. The immobilized laccase can be recycled by a magnetic field and it can keep its active in a long time.We synthesis Fe3O4 by sovent-thermal method, and then Fe3O4 particles was dispersed in ethanol to form magnet fluid. Fe3O4@SiO2 particles and chain composite are synthesized by StOber method. The coated particles were processes by APTES.Laccase was fixed on amino nano-magnetic carrier by glutaraldehyde. Cross linking agent concentration, immobilization time, enzyme concentration, temperature and pH and other aspects were studied in the immobilize process. It was found that the optimum conditions of amino nano-magnetic carrier immobilized laccase were:at 25℃, glutaraldehyde's concentration was 5%, crosslinking time was 8h, laccase content was 40mg/g, and pH 4.5, immobilization time was 6h.In degradation process,2,4-dichlorophenol's concentration, pH, temperature was studied. It was found that when temperature was 35℃,2,4-dichlorophenol's concentration was 6.5mg/L and solution pH was 5.0, removal rate of 2,4-dichlorophenol was 85%; the degradation rate was 43%. At the same time, the activation energy of 2,4-dichlorophenol's degradation by laccase was studied from dynamics. It was found laccase can degrade 2,4 dichlorophenol at room temperature. The reusability, storage stability of immobilized laccase was studied, In the experiment, after immobilized laccase degrade 2,4-dichlorophenol 5 times, the degradation rate remained above 30%.In the second part, mesoporous spherical silica spheres (MSS) was synthesized by P123 and TEOS. Fe (NO3) 3-9H2O and MSS was mixed by ethanol. The mixture was calcined at a high temperature to obtain spherical mesoporous magnetic material (Fe2O3@MSS). Fe2O3@MSS was handled by APTES to obtain amino mesoporous magnetic carrier.In the immobilized process, cross linking agent's concentration, immobilization time, laccase concentration, temperature, pH and other aspects was studied. It was found that the optimum conditions of immobilized laccase were:at 25℃, the concentration of glutaraldehyde was 4% cross-linking time was 8h, laccase content was 50mg/g, and pH 5.0, immobilized time was 6h.In degradation process,2,4-dichlorophenol's concentration, pH, temperature was studied. It was found that when temperature was 35℃,2,4-dichlorophenol's concentration was 6.5mg/L and solution pH was 5.5, removal rate of 2,4-dichlorophenol was 88%; the degradation rate was 47%. After immobilized laccase degrade 2,4-dichlorophenol 5 times, the degradation rate remained above 34%.