METHOD OF PREPARING CHITOSAN Russian patent published in 1997 - IPC

FIELD: chemical technology. SUBSTANCE: chitosan is used as sorbent and is prepared by grinding natural chitin - containing stock, decalcination with 1.5% hydrochloric acid solution and deproteinazation with 1-5% hydrochloric acid solution and also by washing and deaacylation with 46-47% sodium hydroxide solution. Chitin-containing stock is ground to obtain at least 90% particles having from (+5) to (0.5) fractions. Prior to washing operation, three cycles of deproteination and decalcination are carried out alternately. Each subsequent cycle of the alternating stages is carried out at temperature higher than that in the preceding stage. EFFECT: more efficient preparation method. 6 cl