Immobilization Of Laccase On Ep-Oxy-Functionalizied Periodic Mesoporous Organosilicas

Organically functionalized periodic mesoporous organosilica materials (FPMOs) is a favorable carrier to immobilize enzyme via physical or chemical methods due to the high activity of its functionl groups. In the present thesis, epoxy group-functionalized periodic mesoporous organosilicas was synthesized by the co-condensation of 1,2-bis(triethoxysilyl)ethane(BTESE) and 3-glycidoxypropyltrimethoxylsilane (GPTMS) in the presence of triblock copolymer poly(ethylene glcol)-B- poly(propylene glycol)-B-poly(ethylene glycol)(P123) under acidic conditions. The effect of epoxy group on the mesoscopical ordering, pore structure and other proper-ties of the functionalized PMOs was investigated by mesns of XRD, TEM, solid-state CP-MAS NMR, N2 adsorption-desorption and FT-IR measurements. The epoxy func-tionalized PMOs was used as carriers for laccase immobilization. The adsorption behaviour, the properties and application in degradation of 2, 4-DCP of immobilized laccase were investigated in detail.The structural characterization of functionalized PMOs shows that no cleavage of Si-C bonds occurence during synthesis process and a fraction of epoxy groups has experienced a ring opening reaction to form diol groups. The BET surface, pore vol-ume and pore size decreased with the increase of GPTMS content. The functionalized PMOs still possesses an ordered pore structure when GPTMS concentration reaches as high as 10%,with a surface area of 774.6m2·g-1, a pore vulme of 0.65cm3·g-1, and a mean pore size of 5.2nm.The adsorption equilibrium data of laccase on functionalized PMOs can be well fit-ted by the Freundlich adsorption model and the adsorption processes complies with the pseudo-second-order model. A saturation reaches upon absorption for 4h. The maximum adsorption capacity calculated from pseudo-second order kinetics is 235.85 mg/g, close to the experimental data, and the second-order kinetic constant(k2) is 0.0157 g/mg·h.Compared to these of free laccase, the optimum reaction temperature of Lac-case-FPMOs has increased by about 10℃, and the range of optimum pH has also extended. The pH, thermal, operational and storage stabilities of the immobilized laccase have been considerably improved, which is beneficial for the reuse and stor-age of immobilized enzyme. The Michaelis constant (Km) of immobilized laccase on functionalized PMOs is 378.43×10-3 mol/L. Laccase immobilized on functionalized PMOs exhibits higher efficience in the degradation of 2,4-DCP in queous solution.From the research, epoxy functional PMOs is an excellent carrier for laccase im-mobilization.