Pervaporation (PV) has the potential to separate azeotropic mixtures and close-boiling-point chemicals [1-3]since the process has many inherent advantages over distillation, including reduced energy demands and relatively inexpensive equipment[4,5]. Dense polymeric membranes with extremely small pores in the form of free volume are widely used in the pervaporative separation processes of liquid mixtures. Different from gas-separation membranes, membranes for pervaporation process contact the feed liquid mixture directly. The feed components may not only dissolve into the membrane and alter the polymer chains conformation, but it may also subsequently modify membrane separation performance by the interactions between polymer and penetrant. Therefore, the chemical and physicochemical properties of feed and membrane materials play important roles in pervaporation membrane performance. Polyimide(PI) is now emerging as a promising material for the pervaporation dehydration of alcohol because of its superior chemical resistance and mechanical properties, and lower hydrophilicity.
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