Quaternized PVA-N

N-dimethyl-3-amido-2-hydroxy-propyl ether(QPVA) and sulphate monoesterified polyvinyl alcohol (SMPVA) self-assembled into polyion complex （SAPIC）

the swelling ability of SAPIC membranes in water was the least when the self-assembled solution’s pH value was 7. The homogeneous SAPIC membranes were dipped in ethanol of different concentrations 60 vol%～90 vol% (with 10% as interval) for 48 h

and the permeation behavior of water in ethanol of different concentrations was observed in these homogeneous SAPIC membranes.The homogeneous SAPIC membranes were dipped in 95 vol% ethanol for 48 h

and the pervaporation behavior of water in 95 vol% ethanol was observed in the temperature range of 20～120℃ with an interval of 20℃ in homogeneous SAPIC membranes.A novel experimental approach using FTIR spectroscopy was applied to follow up the scent of the two types of membranes.The absorption peaks of water and poly-electrolyte groups in SAPIC membranes were identified in 1D- or 2D-FTIR spectra and showed that two states of water

free water and associating water

were formed during permeation by polyion groups in SAPIC.Free water first associated with polyion groups in SAPIC membranes with increase of water in ethanol

thus associated water was formed in SAPIC membranes.The 1D-or 2D-FTIR results also showed that two states of water

free water and associating water

esisted during pervaporation in SAPIC membranes.The free water changed earlier than associated water

and free water was first desorbed with increase of temperature and was separated with ethanol.The pervaportion of SAPIC composite membranes was tested

and the results showed that the permeation flux was 1400 g/(m.h)

and the separation factor was 870 for water/ethanol system (containing 95 wt% ethanol).A simple and convenient method was set up for studying the dehydration process of ethanol by using SAPIC membranes.