Studies On The Preparation And The Immobilization Of The Chitosan-Polyacrylonitrile Graft Copolymers

Chitosan-g-AN is the graft polymerization of acrylonitrile (AN) onto chitosan.Because of its water-insolubility, good-penetration and non-toxicity; it is widely used as a carrier of the immobilized enzymes such as papain. pectinase, etc. The unique superiority of the immobilized en~mes effectivel~ clear the protein which causes the turbidity' of beer, fruit wine and so on. Although the graft polymerization of AN onto chitosan has been studied and reported , the optimum process conditions are to be researched further. Only' if chitosan-g-AN is a carrier of the immobilized papain and then it can clear the beer, so far the studies have not been reported.In this thesis the researches has done as the following diagram:The graft olvmerization of AN onto chitosana.select a best redox initiation systemb.researches on the optimum process conditions of graft copolvmerizationChitosan-g-ANBE]Researchonthebestprocess conditions f the immobilized papainThe immobilized papaiTheclarifica-tion of beer3SEResearches on the properties of the immobilized papainThe results of researches are as follows:1.Select a best redox initiation systemThe grafting (6%) ,grafting efficiency (E%) and the rate of the immobilized papain (%) were especially studied for three redox initiation systems such as H202-NH2OH HC1, K2S2O~- NaHSO3 and Cu(LI)-chitosan-H202. After making selective use of these systems, K2S2Os- NaHSO3 was considered as the optimum one . Not only from the view of G% , E%, the rate of the immobilized papain (%) and repeatability , but also simple-aftertreatment and lower cost compared to Ce4~ initiator, the graft polymerization of AN onto chitosan by K2S208-NaHSO3 was excellent. So far it has not been reported on the graft polymerization of AN onto chitosan by K2S-,08----NaHSO3 initiation system.2.After studying on E% and the rate of the immobilized papain(%), the optimum process conditions of the graft polymerization of AN onto chitosan were acquired by applying sevenfactors six levels (U ~) of Uniform Design to arrange experiments.(1)The optimum process conditions of E% were as follows the concentration of chitosan (w/w) 3.35%, AN/chi =7, chi/ K,S208 = 6, NaHSO3/1GS208 =0.538 (these were mcI raio ,the same bellow), reaction time 3 .5h, temperature 40 ~C, 2% HAc (w/w) . (2) The best process conditions of the rate of the immobilized papain (%) were as follows chitosan (wlw) 1.45%, AN/chi 10.5, chi/ K2S,08 = 6, NaHSO3/K2S208 =0.538, reaction time 3.5h, temperature 40 C, 5% HAc%(W/W). Under the optimum process conditions, the followed results were acquired:(1) G%: 195.29% , E%: 92.24% the rate of the immobilized papain (%): 74.63% (2)6%:200.79% , E%: 79.19%, the rate of the immobilized papain(%): 80.83%. Compared to the report of Zheng Lianghua et a!, not only G%~ E% were improving, but also the reaction time was shortened I .5h and the temperature was reduced 20X2. Obviously, it was feasible that the best process conditions greatly- reduced energy usage and production cost. So far this method has noto -been reported.3.The structures of c.hitosan - g - AN were systematically characterized by modem physical methods of IR, SEM, X - ray diffraction. DTG, DTA, etc.4.The best process of using chitosan -g- AN as a carrier to immobiliz~papain were found by L9 (34) orthogonal experiments. The amount of papain 50 mg/g, absorbing time 12h, ionic strength (CN3C,) 0.05 mol U', PH =8.0 . And these results were the same as the results of single factor experiments. On this condition, the immobilized papain had the highest activity and its rate of decomposing protein was 65.23%. So high activity has not been reported yet.5.The properties of the immobilized papain were studied. The optimum PH for immobilized and free papain were 8 and 7 respectively ;the best temperature for immobilized and free papain were 7OXD and 65~C respectively . In comparison with the free papain, at the best temperature, t...