Copolymerization Modification Of Pvtes Pervaporation Ethanol Permselective Membrane

In the production process of fuel ethanol by fermentation, pervaporation technology is commonly used to remove ethanol constantly from fermentation broth in order to reduce inhibition. And the key element of pervaporation technology is membrane materials. So it is important to develop and modify the membrane materials. Our research group has developed a novel PVTES ethanol permselective membrane, the flux of which is1～2order of magnitude higher than the commercializated PDMS ethanol permselective membrane, and the separation factor of which is around5. So it is necessary to modify PVTES to improve the separation factor.In this paper, it is used the modifiers of X (dimethyldiethoxysilane (DMDES), hydroxyl silicone oil (HSO) and polydimethylsiloxane (PDMS)) containing flexible chain segment that modify PVTES, and novel PVTES-X (PVTES-DMDES, PVTES-HSO and PVTES-PDMS) membranes are prepared. Through comparison and analysis of the ethanol permselective performance for PVTES-X and PVTES membrane, combining with the characterization methods of the scanning electron microscope (SEM), atomic force microscope (AFM), analysis of contact angle (CA), fourier transform infrared spectroscopy (FTIR), nuclear magnetic spectra (29Si NMR) X-ray diffraction (XRD) and thermogravimetric analysis (TGA) and so on, the physical and chemical structure of the PVTES-X and PVTES membranes are characterized and the ethanol permselective mechanism of membrane is preliminarily explored. The membrane-forming conditions of R/Si value, film-forming temperature, amount of n-heptane solvent, amount of DBTL catalyst and so on, as well as the operating conditions of feed temperature and feed concentration are systematically investigated for pervaporation performances of PVTES-HSO membrane, using dilute ethanol aqueous solution.The results of experiments are just as follows:the surface structure of the PVTES-X and PVTES membranes is smooth and dense, and the film-forming property is also good. And PV experiment proves that separation selectivity of PVTES-X membrane increases compared with PVTES membrane, of which the separation selectivity of PVTES-HSO membrane is the highest. The pervaporation performance ofPVTES-HSO membrane exhibites good while film-forming temperature is60℃,1.4of R/Si value, lOg of solvent heptane amount and0.2g of catalyst DBTL amount. And when feed concentration is9wt%and feed temperature is35℃, the separation factor of PVTES-HSO is around6.6and flux up to8160g/(m2·h). With the increase of feed temperature, separation factor remains at around6and permeation flux increases gradually for PVTES-HSO membrane. And with the increase of feed concentration, separation factor reduces and permeation flux increases gradually for PVTES-HSO membrane.