The Preparation And Application Of Chitosan And It's Series Product

In this paper, we prepared chitosan from the crab shell, catalyzed by the NaOH. We studied the influence of the temperature ^ the density of the NaOH > the times of the basification and the microwave etc. to the preparation of the chitosan. At the same time, we got the CM-chitosan and CM-chitin. The influence of the microwave and ultrasonic to the reaction was studied, the preparation condition was optimizated. In order to improve the product technics, we dipped the chitosan in the low-temperature NaOH liquor before the basification and join the phrase-transmit catalysis. The adsorption to the Ag+ of the chitosan and CM-chitosan was researched. We use CM-chitosan as the antisepsis regents to the apricot. And finally we studied the hydrolysis dynamics of the CM-chitosan.In the preparation of the chitosan, we basified the materials repeatedly, and supplied the new lye and got rid of the impurities produced in the reaction and we got the high D.D. chitosan.(the 90% ^D.D. ^96%)The extinct characters of the microwave is to reduce the reaction time greatly, and so we can controlled the hydrolysis of the chitosan and CM-chitosan, it is important to cut down the energy exhume and improve the quality of the production.we studied the hydrolysis of the CM-chitosan, and the molecular weight was reduced to about 8000. The introduce of the carboxyl made the CM-chitosan resolved in the water when the PH was 7.0, so the -NH2 can be attacked easily. So the hydrolysis is high greater than the chitosan.Compared to the chitosan, the CM-chitosan were more suitable to adsorption of the Ag+ , the time was less than 15min when it became saturated.The antisepsis result of the CM-chitosan was different according to the different D.D. Through the experiment we find there was best antisepsis to the apricot when the D.D.was 0.4. The chitosan can made a membrane over the fruits, kept the O2 out side and restrained the breath, and kept the fruits fresh.