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 x 10(-3) h(-1) to 22.8 x 10(-1) 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 degrees 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. (C) 2009 Published by Elsevier Ltd.