Water permeability of chitosan membrane involved in deacetylation degree control

Chitosan membrane was prepared by the casting method in combination with N-acetylation reaction. Deacetylation degree decreased linearly with increasing added amounts of acetic anhydride. The stoichiometric control of the deacetylation degree to the desired level was successfully performed. The maximum stress and strain were measured and were linearly depended on the deacetylation degree. The chitosan membrane produced by the casting method had an asymmetric cross-section in the thickness direction based on scanning electron microscope. The solubility of the chitosan membrane changed with pH. Ranging over pH 6.6, the chitosan membrane was still stable and had elasticity. The volumetric permeated water flux through the chitosan membrane increased linearly with operational pressure. It was exponentially dependent on the deacetylation degree and was satisfactory at a constant level after repeated use. The deacetylation degree was anticipated as a parameter for production of chitosan membrane for practical applications.