| This thesis studied the method and process to produce chitosan and highly sticky chitosa using shrimp and crab's hull as the primary raw material. Parallel experiments were carried out to make sure the best preparation conditions of chitosan and highly sticky chitosan were used. Furthermore, the products properties were determined. The spectrophotometric method was used for measuring the flocculent property, by experimenting with four kinds of industrial wastewater and one suspension of yellow mud slurry, the condition and the effect of flocculate of the chitosan are discussed further. Moreover, a preliminary study of the experiment's conditions of methylcarboxylated chitosan was carried out.1. A method of soaking the raw material in acid and boiling in alkali was used to prepare chitosan. The best preparation steps and conditions for chitosan production was firstly at room temperature soaking the raw material with10% hydrochloric acid solution for 4 hours, then boiling at 100℃ in 25% sodium hydroxide solution for 3 hours, then at room temperature, using 8-10% hydrogen peroxide solution to remove color for 3-4 hours, then heating at 100℃ in 50% sodium hydroxide solution for 3 hours, protection with nitrogen gas for deacetylation. 2.Alkali solution was used to soak the feedstock twice for preparing highly sticky chitosan. For removing calcium(soaking in acid) , protein(soaking in alkali solution) and decoloration( soaking in hydrogen peroxide solution) the same treatment conditions was used as in the preparation of chitosan. But it need two times soaking in alkali solution to deacetylate. Namely, soaking with 50% hydroxide sodium solution for 8 hours in water at 60-65℃, while protecting with nitrogen gas, then cooling to room temperature.Next day, washing with hot water, then soaking with 50% hydroxide sodium solution for 8 hours at 60-65℃ again, leave it over night, then on the following day, use filtering, then washing with hot water until it is neutral, then drying at 80℃ to obtain the product.3.The products properties were determined. The prepared chitosan can dissolve in diluted acid solution at short time. Deacetylation degree is 90.34%(highly sticky chitosan's deacetylation degree is 86.46%). Viscosity is 756.72, highly sticky chitosan's viscosity isl562.18, compared to industrial chitosan's viscosity 1189.15 and deacetylation degree, the prepared chitosan has reached the level and standard of industrial product.4. The prepared methylcarboxylated chitosan was characterized with IR spectrum, which isconsistent with the standard product spectrum.5.The prepared chitosan was used to treat four kinds wastewater from chemical industry. Inrespect of color removal, chitosan is better than aluminium salt, it can remove color further afterfirst flocculation with aluminium salt.6. The industrialization of chitosan preparation process has been preliminarily studied. Theindustrialization technique for chitosan preparation has been set up. |
