Preparation Of PVA/PPESK Membrane For Vapor Permeation

Vapor Permeation (VP), as a novel separation technology, attracted a wide spread attention for its outstanding technical advantages such as high selectivity and convenient operating. This technique has promising application prospects in the separation of azeotrope for it can breakthrough the limitation of vapor-liquid equilibrium. In this study, PVA/PPESK membrane has been prepared on vapor permeation for ethanol dehydration.PPESK macroporous ultrafiltration membrane has been prepared as the support layer of vapor permeation membrane for ethanol dehydration. The effect of the composition of casting solution and the technological conditions for membrane-making on the performance andstructure of PPESK UF membrane has been researched by determination of pure water flux,retention rate, and SEM. The results show that the pure water flux decrease and the retention rate increase with the increasing concentration of PPESK. The pure water flux increase with the concentration of DegOH, and the retention rate decrease while the concentration of DegOH increased. The pure water flux increase and the retention rate decrease with the decreasing of vapor time or increasing temperature of coagulation.Meanwhile, PVA homogeneous membrane was prepared, which was crosslinked with glutaraldehyde. The effect of the polymerization degree, crosslinked degree, concentration and temperature of steep liquid and steep time on the swelling of PVA homogeneous membrane in ethanol/water mixture was studied. The results showed that swelling degree increase with the increasing of polymerization degree or decreasing of crosslinked degree. The swelling degree decrease from 1.4 to 0.3 while concentration of ethanol. The effect of temperature on swelling degree is now obvious in high concentration of ethanol.Then, PVA/PPESK composite membrane was prepared using PPESK UF membrane as support layer and using PVA as the separating layer. The performance indexes of these composite membranes in the separation of the ethanol/water azeotrope were tested by home-made performance evaluation device. The result shows that, PVA layer is the selective layer. The flux of composite membrane increase while pore diameter increasing. But porosity-permeability occurred while pore diameter increasing, which lead to the decreasing of lux.At last, the membrane was prepared by selecting the suitable formula of the basement membrane and the coating layer. The separation factor of this membrane can reach up to 210, and the permeation flux can reach up to 138g·m^-2·h^-1 . The simulation result by HYSYS system shows that the concentration of ethanol can be enriched up to 99.5% while the membrane area is 750cm².