Kinetics of N-Deacetylation of Chitin Extracted from Shrimp Shells Collected from Coastal Area of Morocco

Chitosan was obtained from the alkaline N-deacetylation of -chitin, derived from shrimp shells (SS) collected from the Moroccan coast. Effects of temperature, NaOH concentration and reaction time on the kinetics of deacetylation were studied. The degree of deacetylation (DD = 75%) was obtained at T = 120 °C and CNaOH = 12N in a single step for 6h. It was found, from FTIR studies, that the removal of acetyl groups from chitin occur very fast for the reaction time t < 180 min and then becomes constant after, revealing two steps in the deacetylation of chitin following a first-order kinetics for each of them. The second step is considered the limiting step that has, in the temperature range of 25 – 120 °C and maintained CNaOH = 12N, a low apparent rate constant. The activation energy of this step is about 48.76 kJ/mol. The biopolymer (Chitin and chitosan) produced were characterized by X-ray diffraction.