Effect of diffusional limitations on the kinetics of deacetylation of chitin/chitosan

A new model is proposed for the kinetics of the heterogeneous deacetylation of chitin/chitosan. This new model is able to represent the process over much broader ranges than the other kinetic models reported in the literature. The unreacted shrinking core model was modified with the inclusion of increasing diffusional effects as the reaction progresses, causing the rate to slow down and preventing the degree of deacetylation reaching 100 %, even in the presence of excess NaOH. The model was validated with data collected in experiments with different NaOH concentrations and temperatures. The proposed model was able to represent the experimental data correctly over the entire experiment span, resulting in a model with proven predictive ability, in contrast to existing kinetic models that have been applied in a piecewise fashion over a rather limited time range of the process. The proposed model represents an improvement in the understanding of the deacetylation process.