Study On Preparation And Property Of Carboxymethyl Chitosan

Among the waste produced in the processing of seafood, the shrimp shell make up a large percentage. To the best of our knowledge, the shrimp shell contains rich chitin which has a high value in use. The comprehensive utilization of these waste can not only save the resource and protect the environment, but also create a good economic value and social value. Based on this idea, in this thesis, we extracted chitin from the waste shrimp shells in Qingdao city with an optimized process firstly. Then, chitosan and carboxymethyl chitosan (CMC) were prepared starting from these extracted chitins, and the properties of chitosan and CMC have been studied in detail.At first, the extraction process of chitin from the shrimp shells was studied. By means of the single factor experiment, we have found that the optimum conditions for removing calcium ion in the extraction process are that the concentration of EDTA-Na2is6%, the pH equals6, the reaction time is13h, and the reaction temperature is25℃. We have also found that the albumen could be eliminated well from the system in the presence of sodium hydroxide (6%concentration) at90℃within4h. The yield of chitin under these optimized conditions could be promoted to18.91%. Meanwhile, the ash content dropped to1.43%and the protein content was4.29%.Secondly, the method for the preparation of chitosan using the extracted chitin as starting material has also been studied by single factor analysis. In the presence of sodium hydroxide (50%concentration), chitosan was produced in10.36%yield at100℃within6h. Also, D.D of the provided chitosan under these optimized conditions is91.44%and the viscosity is411.5mPa-s.The third part of our research is screening the conditions of preparing CMC with chitosan by means of the single factor experiment.2g of chitosan reacted with9g of sodium hydroxide and lOg of chloroacetic acid at60℃within4h, affording CMC in the high yield of96%. To our satisfaction, DS of the prepared CMC under these conditions is1.01, and the viscosity is1234.5mPa·s. In addition, the solubility of the prepared CMC is1.26g.At last, we prepared CMC-gelatin mixed membrane by treating CMC with gelatin and glycerol in a certain ratio. The optimum conditions of the preparation of CMC-gelatin mixed membrane are that the concentration of CMC is2%, m(CMC):m(gelatin)=1:4, the glycerol content is0.5%, and the reaction temperature is60℃. The given mixed membrane showed better properties, such as good tensile strength(45MPa), good elongation at break (13.2%) and good moisture rate(35%). In addition, the air permeability of afforded membrane is11.2×10-15and the moisture-penetrability is0.234g-mm/m2-d-kPa.