Peculiarities of the Transport Properties of Chitosan Films. 2. Density of Pervaporation Flux through Chitosan Films with Different Areas

Transmembrane flux density may depend on membrane area, provided that the properties of the membrane vary with variations in the latter. This situation takes place for pervaporation processes realized with the use of chitosan films swelling in water-isopropanol solutions being separated. In this work, the flux density and permeate composition have been determined as depending on the composition of a molding solution containing a precipitant as one of its components, concentration of a solution being separated, and film area (2 and 20 cm2) in pervaporation setups. Irrespective of the composition of a molding solution, abnormally high flux densities of water and isopropanol, as compared with the flux density of a water-alcohol solution, take place for chitosan films with an area of 20 cm2. When the pervaporation is performed through a 2-cm2 film, all observed abnormalities disappear with the exception of the only one: the permeates is enriched with isopropanol in all experiments.