Summary
The Studies on the Ability of Various Acids to Hydrolyze Chitosan and Chitin
The studies on acid hydrolysis of chitin and chitosan by four inorganic acids HCl, HNO3, H2SO4 and H3PO3 in concentration of 2 N and at temperature of 100oC were carried out. The ability of various acids to hydrolyze these polysaccharids was assessed by: 1) determining amounts of chitin and chitosan remained unhydrolyzed after 8 hour hydrolysis; 2) determining amounts of reducing sugars, formed at reaction times of 1, 2, 4, 6 and 8 hours; and 3) formation of by-product that is a derivative of furan such as furfufol or hydroxymethylfurfurol.
The obtained results showed that under the given reaction conditions chitosan is better hydrolyzed by phosphoric acid and the ability of acids to hydrolyze chitosan is decreased in order: HNO3» H3PO4> H2SO4> HCl, while in the case of chitin was observed following one: HNO3> HCl > H2SO4> H3PO4. But nitric acid seems unsuitable for hydrolysis of these polysaccharids, because in the solution of this acid almost all reducing sugar formed in the hydrolysis reaction was converted into by-product, with the maximum of absorption at 300 nm.
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