Water Sorption on and Water Diffusion in Chitin and Chitosan

A. E. Chalykh^a, T. F. Petrova^a, R. R. Khasbiullin^a, and A. N. Ozerin^b

^a Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Science,
Leninskii pr. 31, Moscow, 119071 Russia

^b Enikolopov Institute of Synthetic Polymer Materials, Russian Academy of Science,
ul. Profsoyuznaya 70, Moscow, 117393 Russia

e-mail: chalykh@mail.ru

Received December 12, 2013;
Revised Manuscript Received April 10, 2014

Abstract—The kinetics of the sorption of water vapor on powders of crab-shell chitin and chitosan are studied
via the methods of static sorption, thermography, and X-ray structural analysis. Sorption isotherms are obtained
in the range of humidity from 10 to 95%. S-Shaped water-sorption isotherms observed for all chitin and chito-
san samples are approximated via superpositioning of Langmuir and Flory–Huggins isotherms. The water–
polysaccharide interaction parameters and the maximum sorption capacities of water located in chitin and chi-
tosan are determined. The cluster integral is calculated, and the moisture values corresponding to water-cluster
formation are determined. The water-diffusion coefficients are determined, and the effective activation energies
of water diffusion are estimated: 70 kJ/mol in chitosan and 60 kJ/mol in chitin. The data on the concentration
dependences of the coefficients of diffusion of water in the powdered chitin and chitosan are summarized.

DOI: 10.1134/S0965545X14050034

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