Deacetylation of Chitosan

Chitosan powders were added to a 45% sodium hydroxide solution in a 1:10 (W/V) ratio in a
reaction vessel following Zhang’s method [14] and the reaction was under nitrogen atmosphere. The
powders were subjected to one of the following reaction conditions: (1) 80 °C for 20 min; (2) 80 °C for
60 min; (3) 90 °C for 60 min; or (4) two 60 min treatments at 90 °C (Tables 2 and 3). After reacting,
the product was filtered and washed with distilled water until a neutral pH was obtained. The resulting
products were dried in an oven for 24 h at 40 °C, then in a vacuum oven for 24 h at 40 °C.