Study On The Decolorization And Degradation Of Synthetic Dyes Catalyzed By Laccase From White Rot Fungi Ganoderma Lucidum

Our country is a big country of textile industry that has dyeing wastewater quantity which causes serious pollution to the environment. Conventional water pollution treatment technology can’t be a better solution to settle this problem but with the rapid development of biological science, Biological enzymatic process dyeing wastewater has been presented the good development prospect. Laccase is one of multifunctional oxidoreductases that catalyze the oxidation of a variety of phenolic compounds, It has a wide range of substrates and widely used in many fields. especially which has its unique superiority in the treatment of dyes wastewater. Different sources of laccase have different ability to degrade the txtile dyes, so aims to the unique degradation function of laccase to dye this thesis studied the degradation ability of different structure synthetic dyes(azo-type、phthalocyanines) by crude laccase obtained from white rot fungi G. lucidum, meanwhile discussed the condition of G. lucidum immobility, the characterization and decolorization ability of the immobilized laccase were also explored. The major results were as follows:(1) Decoloration effect of monoazo dyes by G. lucidum laccaseThe decoloration of the five types of monoazo dyes by G. lucidum laccase was studied, also compared with the decoloring effects between laccase-cataly-zed and laccase/mediator-catalyzed systems, The decolorizing conditions that without mediators for reactive brilliant red M-8B were optimized The results were showed as follows:100mg/L of initial dye concentration,2.5U/mL of laccase dosage,15mmol/L of Cu2+addition and pH3.5at40℃. (2) Decoloration effect of disoazo dyes by G. lucidum laccaseCompared with the decolorization of four types of disoazo dyes between laccase-catalyzed and laccase/mediator-catalyzed systems by G. lucidum laccase and Choose reactive black5as the research object, The decolorizing conditions that without mediators for reactive black5were optimized which was25mg/L of initial dye concentration,2.0U/mL of laccase dosage,40mmol/L of Cu2+addition and pH6.0at40℃. Under the optimized conditions, more than90%of reactive black5was decolorized in24hours respectively.(3) Decoloration effect of threeoazo dyes by G. lucidum laccaseTo direct fast blue B2RL as the research object, we studied the decoloration effect by G. lucidum laccase and The single factor optimization method was used to confirm the best reaction conditions without mediators, which was pH7.0and50℃, with2U/mL laccase dosage and150mg/L of dye concentration.(4) Decoloration effect of phthalocyanine dyes by G. lucidum laccaseIn this paper we used G. lucidum laccase to decoloring three types of phthalocyanine dyes, We choose direct blue86as the research object to optimize the decolorizing conditions that without mediators, According to the results of Single factor experiment, we got the best decoloring conditions through the4factors3levels response surface analysis for the decoloring rate which was190mg/L of initial dye concentration,1.4U/mL of laccase dosage and pH4.8at39℃.(5) The immobilized research of G. lucidum laccaseTo the activity of immobilized laccase as the index,We immobilized G. lucidum laccase though Sodium alginate (embedding method)、Chitosan-glut-araldehyde (adsorption-crosslinking method) and Sodium alginate-chitosan (embedding-crosslinking method), Compared these methods, the embedding-crosslinking method was the best to us, Using the response surface method to optimize immobilized conditions We concluded that the best was Chitosan concentration of quality0.035g/mL、laccase quality1.6mL、Sodium alginate concentration of quality0.06g/mL、CaCl2concentration of quality0.03g/mL glutaraldehyde concentration of quality0.025g/mL.(6) The characters of the immobilized laccaseWe studied the characters of the immobilized laccase,The results showed that the optimum pH and temperature for the immobilized laccase were4.0and40℃, It also has good storage stability and operational stability.(7) Decoloration of Synthetic dyes by immobilized laccaseWe studied the decoloration of the four Synthetic dyes by immobilized laccase and have got a good decoloring effect, more than that it could repeated decoloring which improved the efficiency in the use of laccase.