Effects and kinetics of a novel temperature cycling treatment on the N-deacetylation of chitin in alkaline solution

The influences of alkaline concentration, cold-treatment temperature, cold- and heat-treatment method, reaction time and the ration of chitin powder to NaOH solution on the N-deacetylation of shrimp chitin were investigated. The effects of the alkaline concentration, cold- and heat-treatment method and reaction time were significant; nevertheless, the effects of temperature and the ration of chitin to solution were insignificant. The N-deacetylation followed the pseudo-first-order kinetics. The apparent rate constants of the reaction ranged from 3.3 × 10−3 h−1 to 22.8 × 10−3 h−1, and the apparent activation energy was preliminary estimated about 9.76 kJ/mol at aqueous 35% NaOH solution, in the temperature range of −5 to −35 °C, which was much lower than that of previous literatures. The effect of novel temperature cycling treatment on the reaction process and structure of chitin, compared with the single alkali-freezing treatment, was greater. So the novel temperature cycling treatment could be regarded as a more efficient novel pretreatment method for further modification of chitin.