Permeability of CO2 through chitosan membrane swollen by water vapor in feed gas

The permeation and separation of carbon dioxide through a water‐swollen chitosan membrane was studied. A chitosan membrane was swollen by water vapor contained in a feed gas and, thus treated, exhibited a large gas permeability. Carbon dioxide preferentially permeated through the swollen chitosan membrane with a permeability of 2.5·10−8 cm3 (STP) cm(s cm2 cmHg)−1 and a CO2/N2 separation factor of 70 at room temperature. This separation performance for CO2 resulted from the basic properties of the chitosan amino groups. The membrane preparation conditions, such as acetic acid concentration of the casting solution, affected the membrane permeation rate. The effect of the operation temperature was also measured. To increase the separation performance of the membrane, several methods of membrane treatment and operation were evaluated.