CHITOSAN MANUFACTURE PROCESS

FIELD: natural-origin polymers. SUBSTANCE: natural chitin stock is crushed and extracted for 1-3 h with liquid carbon dioxide. Then follows first-stage decalcification with 4-10 volumes of 0.8- 2.5% aqueous hydrochloric acid conducted for 0.5-2 h at 35-50 C. Partially decalcified material is washed with water and subjected to first-stage deproteinization with 0.1-0.5% (based on the weight of dry chitin-containing powder) enzyme conducted for 1-4 h at pH 9.0-10.5 and temperature 50-70 C with 4-7-fold excess of water. Intermediate product is separated, washed, and subjected to second-stage decalcification with aqueous hydrochloric acid followed by washing and second-stage enzymatic deproteinization. Further, intermediate product is deacetylated with sodium hydroxide, resulting chitosan is separated from mother liquor, washed and dried. EFFECT: simplified process, reduced process time, reduced consumption of chemicals, and increased molecular weight of chitosan. 2 cl, 3 ex