| Immobilization of enzyme is an effective means to make enzyme reuse and maintain theproperty of continuous enzymatic catalytic reaction. The soluble enzyme treated with physical orchemical methods is combined to or embedded in insoluble carrier so that the free enzyme isrestricted to certain area and the free enzyme wound not loss with water. The emission of sewagegenerated by industry is serious harmful to the health of our lives and led to increasingly seriousenvironmental problems that make people’s living standards decline. Pollution of phenolicwastewater in the industrial sewage, which is one of hazardous waste that needs to focus onresolving in our country, has become a global problem. Therefore, the degradation of phenoliccompounds in water is an important research topic at home and abroad. Immobilized enzyme,which is efficient and reusable, can effectively solve the problem of water pollution. In this paper, akind of novel macroporous silica was organic functionalized and then employed as the support forthe immobilization of laccase. And the conditions of immobilization of laccase, the property ofimmobilized laccase and degradation of phenolic compounds in water by the immobilized laccasewere studied.1. A novel large-sized macroporous silica material was amino-modified via post-graftingmethod under solvothermal conditions. The amino-functionalized macroporous silica wereemployed as the supports for immobilization of the commercial Novozymes laccase by usingglutaraldehyde (GA) as the activating agent. The results show that under the concentration of3%glutaraldehyde, immobilizing time of4h, the buffer of pH5.0and the initial laccase concentrationof30mg/mL, the activity of immobilized laccase reaches111.4U/g. Compared with the freecounterpart, it is found that the pH and thermal stabilities of the immobilized laccase are improvesignificantly, and the immobilized laccase retaines70.8%of its intial activity after ten times ofcatalytic reaction, indicating that the immobilized laccase is of good reusability.2. The immobilized laccase, which is immobilized on amino-functionalized macroporoussilica, was employed as catalyst for the degradation of phenol. The results showed that the removal of phenol was attributed to the combined effect of adsorption and biodegradation. However,enzymatic oxidation of phenol by the immobilized laccase played a dominant role. At pH of5.0,phenol concentration of8mg/L and the temperature of50℃, the degradation efficiency of phenolby the immobilized laccase after5h reached the maximum (70.1%). Coupled with adsorption ofphenol by the carrier of immobilization, the removal rate reached90.3%.3. A new chitosan/silica macroporous organic-inorganic (CS/SiO2) composite, which has alayer of ultra-thin film structure, was prepared by coating cross-linked CS on macroporous silica.CS/SiO2was employed as the supports for immobilization of laccase by using glutaraldehyde (GA)as the activating agent. The studies have shown that the optimum conditions of immobilization oflaccase are as following: The CS/SiO2composites are activated with3%(v/v) glutaraldehyde, themaximum activity of immobilized laccase reached185.8U/g under the pH of5, laccaseconcentration of80mg/mL and react time of5h. Compared with the free laccase, the pH andthermal stabilities were improved significantly after laccase was immobilized on the support.Moreover, the immobilized laccase has good operational stability.4. The immobilized laccase with the CS/SiO2macroporous composites as support was usedfor removal of2,4-DCP in water. The degradation time, pH, temperature and the initialconcentration of2,4-DCP were studied in the degradation process. It was found that when thedegradation time was6h, the concentration of2,4-DCP was10mg/mL, solution pH was7andtemperature was45°C, the removal rate of2,4-DCP reached93.0%and the degradation rate was72.7%. The removal rate of2,4-DCP degraded by immobilized laccase remained76.3%after fourcycles of operation... |
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