Response surface experiment results
Figures 1 present the response surface as a 3-D plot, enabling the
prediction of DD% for varying test variable values and the
identification of their interaction. The interaction between all
variables in the DD% response is found to be statistically significant
(Table 4).
In order to optimize and validate the predicted mathematical model,
additional Expert Design runs were conducted using the same experimental
conditions. The accuracy of the model was significantly enhanced by
increasing the desirability function. The optimal parameters,
corresponding to a desirability value of 0.99, resulted in a DD% of
93.98% (Fig. 2). Under the specified conditions, the highest achieved
DD% was attained with the following parameters: NaOH concentration
(1.41 M), demineralization time (15.75 hours), HCL concentration (7.49%
vol), deacetylation time (2.01 hours), and deacetylation temperature
(81.15 °C). Chitosan samples were prepared using these conditions and
subjected to characterization analysis.