ipjE04130206 Enhancement of Chitins Degree of Deacetylatn by Multistage Alkali Treatments

In this study chitin was extracted from Persian Gulf shrimp''s shell and deacetylation was carried out with 5 wt% NaOH at 90°C in a nitrogen atmosphere.Chitosan was preparedwith high degree of deacetylation. The effect of deacetylation conditions in the multistage alkali treatments in comparison with continuous alkali treatment was studied. Chitosan’s nitrogen content and the extent of degree of deacetylation were measured using FTIR spectroscopy and elemental analysis (CHNO analysis) respectively. Significant differences observed between multistage and single stage alkali treatments on the nitrogen content and degree of deacetylation of the resultant chitosan. In the multistage treatments deacetylation of chitin reached to 90.9% that is effective to improve biomedical application of the resultant chitosan. The morphological effect of the chitin macromolecules chains and the alkali agent concentration as a driving force for promotion of deacetylation reaction were studied. Our results showed that the ability of NaOH diffusion into chitin macromolecules was highly decreased in the continuous treatment while in the multistage treatments the degree of deacetylation was enhanced due to more diffusion of the alkali agent into chitin macromolecules and many acetamide sites on these chains were subjected to alkali treatments.