| Acetic acid is one of the most demand products in the chemical industry. Although acetic acid and water mixture is not an azeotropic compound, the relative volatility of water to acetic acid is close to unity. It becomes even more difficult to separate by distillation as the compositions of water in liquid and vapor phase approach almost equal, especially in the region of the acetic acid content being higher than 80 wt%. A conventional dehydration of acetic acid is completed by distillation an energy-consumption skill. So the separation of acetic acid from water is an eye-catcher task. As a novel separation technology, pervaporation (PV) is very economical to remove the component from the mixtures when its content is lower than 20 wt%. The most used hydrophilic membranes, such as Poly(vinyl alcohol)(PVA), Polyacrylic acid (PAA), Ployacrylonitrile (PAN) and sodium alginate(NaAlg), show discouraging separation capability in PV of acetic acid aqueous for its strong acidity. From the dehydration of acetic acid in industry, novel membranes used for this purpose were prepared by modifying Cardo polyetherketone (PEK-C) (which is solvent resistance and hydrophobic) for the first time. The membranes were characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR), Scanning electron microscope (SEM), Transmission electron microscope (TEM), Differential Scanning Calorimetry (DSC) and contact angle meter, and their swelling and sorption properties, diffusion properties, and pervaporation properties were investigated systematically.The hydrophilicity of PEK-C can be effectively endowed by reacting it with concentrated sulfuric acid, and the hydrophilic-hydrophobic balance of the membranes can be realized by controlling the sulfonation degree (SD), and the membranes maintain well swelling resistance in the acetic acid aqueous. The pervaporation separation index (PSI) of the SPEK-C membranes increased with SD increasing, and it arrived at an optimum when the SD is 0.75. The membranes has good separation performance with a permeation flux of 248 gm-2h-1 and separation factor of 103 at 50℃at the feed water content 10wt%.In order to improve the permeation flux of the SPEK-C membranes, PVA and SPEK-C blending membranes were prepared. SEM result shows that the PVA and SPEK-C are compatible, and the membranes are homogeneous. XRD indicates that the intermolecular distance of the polymer chains increases with PVA content increasing. The permeation flux increases and the separation factor decreases with PVA content increasing. The PSI of the membranes increases with increasing PVA content and arrived at a maximum when the PVA content is 40wt%, then decreases with further addition of PVA. The membrane has an encouraging separation performance with a permeation flux of 492 gm-2h-1 and separation factor of 59.3 at 50℃at the feed water content 10 wt%.The "trade-off" effect of PVA/SPEK-C blending membranes was solved by filling high hydrophilic silicotungstic acid (STA) into the blending membranes. The pervaporation results show that the permeation flux increased with STA content increasing; however, the separation factor increased with STA content increasing, and arrived at a maximum when the STA content is 12 wt%, then decreased with STA content further increasing. The PSI of the membranes achieved the maximum when the STA content is 12wt%. The membranes show encouraging separation performance with a permeation flux of 597 gm-2h-1 and separation factor of 70.3 at 50 C at the feed water content 10wt%.Glutaraldehyde (GA) cross-linked SPEK-C and STA-PVA-SPEK-C homogeneous membranes and composite membranes with a microporous PEK-C substrate were prepared. The PV performance of the homogeneous and composite membranes was investigated. The PV results show that the performance of composite membranes is higher than that of homogeneous membranes under the same operation condition. SEM and PV experiments show that the compatibility between the STA-PVA-SPEK-C/GA layer and the PEK-C substrate and PV performance can be improved by using water and DMSO as a co-solvent for STA-PVA-SPEK-C/GA instead of using DMSO as a solvent only. The permeation flux and separation factor of STA-PVA-SPEK-C-GA/PEK-C composite membranes, using water and DMSO as a co-solvent, could be to 592 gm-2h-1 and 91.2 at 50℃at the feed water content 10wt%, respectively.
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