STUDIES ON THE SELF-DIFFUSION OF WATER ETHANOL MIXTURE IN CHITOSAN PERVAPORATION MEMBRANE WITH PULSED FIELD GRADIENT NMR DATA

The self-diffusion of water, ethanol and water-ethanol mixtures in chitosan (CS) membranes crosslinked byaqueous H2SO4 solution and uncrosslinked membrane was measured using pulsed-field gradient (PFG) nuclear magneticresonance (NMR) spectroscopy to obtain the partial solubilities and self-diffusion coefficients. An attempt was made toexplain the transport properties of water and ethanol through the CS membrane. It was concluded that there are two types ofchannel water and ethanol diffusate transfer. The water was localized in the hydrophilic ionic region formed by the ionizedgroups, and the ethanol was localized in the hydrophobic amorphous network of the polymer. There was a good agreementbetween the separation factors estimated from PFG-NMR data and those obtained by pervaporation testing.