Continuous Preparation Of Acrylamide By Immobilized Nitrile Hydratase Producing Strain Catalyst With Sodium Alginate

Acrylamide is a fine chemical product which was very important. It can be used to compose polyacrylamide, applied to coal mining, metallurgy, papermaking and water treatment, further more,"tertiary recovery"is its main applied area. So in recent years, the demand of polyacrylamide and its monomer acrylamide is growing increasingly at home and broad, the study on the producing methods of acrylamide is popular. Using immobilization technology and the microbial methods for continuous producing acrylamide has many benefits such as process simple, immobilized cells can be used for a long time, low cost and the catalyst's separation and recovery easily.In the prior period of my study, isolate and filter a strain which can produce nitrile hydratase from activated sludge of wastewater treatment plant. Then tame this strain and search the best conditions of preservation and activation to obtain a nitrile hydratase producing strain which has high enzyme activity. In the next period, the nitrile hydratase producing strain was immobilized on sodium alginate carrier by embedding method, and using enzyme column continuous-flowup reactor designed and made by myself to have the preparation acrylamide action. The best immobilized conditions and parameters of consecutive reaction process were studied respectively. At the same time, compare the continuous reaction with batch reaction. The mainly results are as followed:A nitrile hydratase producing strain of 476.8U enzyme activity can be isolated and filtered from activated sludge of wastewater treatment plant when the concentration of acrylonnitrile was 2g/L, the dilution degree of activated sludge was 10^-5 choosing acrylonitrile as the filtering factor, named it as nitrile hydratase producing strain JSHM-1. Tamed the strain gradually using acrylonnitrile, when the concentration of acrylonnitrile accounted to 8g/L, the result of taming was the best, that was the enzyme activity can raise to 962.4U. As the concentration of acrylonnitrile was 4g/L, the enzyme activity of JSHM-1 can keep 927.5U during preservation and 971.6U during activation, which were both best, in the mean time, the method of solid culture was better than fluid culture.When the nitrile hydratase producing strain was immobilized on sodium alginate carrier by embedding method, and using the immobilized cells to catalyse acrylonnitrile to acrylamide continuously, the optimal immobilized conditions were as follows: the mass fraction of SA solution was 4.0%, the cell dosage was 1.0g/L, the mass fraction of CaCl₂ was 5.0%, when immobilized for 6 hours at 4℃, the relative enzyme activity was the highest, reached 93.4%. When the immobilized cells were used in continuous catalyzed reactions for 6 hours, the relative enzyme activity was still 53.8%. And the best parameters of consecutive reaction process were like these: when cells were immobilized under optimal conditions, the flow rate was 10ml/min, the volume fraction of substrate acrylonnitrile was 3.0% and the filling density was 6/cm³, the relative enzyme activity can reach 94.2% and keep 60.0% as reacted for 6 hours if the reaction was did under the conditions up. The continuous reaction was better than the batch reaction in terms of both relative enzyme activity and reacted time.