Study On Evaluation Of Performance And Swelling Behavior Of Poly (Vinyl Alcohol) Pervaporation Membrane

As a material of pervaporation membranes, poly vinyl alcohol (PVA) was used for ethanol dehydration. PVA homogeneous membrane and PVA/PAN composite membrane were prepared, which were crosslinked with glutaraldehyde. The microstructure of membrane was observed directly by means of a scanning electron microscope (SEM). The results indicated that the surface morphology of PVA homogeneous membrane and PV A/PAN composite membrane were flat, slippery and compact, and the PVA active layer and PVA support layer were well-knit.The effect of the polymerization degree, concentration and temperature of steep liquid and steep time on the swelling of PVA homogeneous membrane for ethanol/water mixture was studied. The results showed that water was preferential adsorption and permselectivity solution in PVA membrane.The pervaporation equipment was designed and established including a key module— pervaporation cell which had an arc liquid channel. The effect of operation conditions (such as temperature, feed concentration, downstream side pressure and flow velocity) on separation performance was studied. The results showed that flux increased with the increase of water composition, temperature and flow velocity in feed, and decreased with the increase of the downstream side pressure;the separation factor increased with the increase of temperature and flow velocity in feed and decreased with the downstream side pressure;the effect of ethanol concentration in feed on the separation factor was complicated;the separation factor was up to 2680 at ethanol in feed of 94.5%.The improved UNIFAC and Flory-Huggins models were established and applied to predict and correlate the swelling behavior of PVA membrane in ethanol-water mixture. The improved UNIFAC and Flory-Huggins models were well consisted with the experimental data for the ternary system PVA-ethanol-water. Contrastively, the improved UNIFAC model was fit for more occasions, and the calculative precision of the Flory-Huggins model was better than the improved UNIFAC model.