Exprimental Study On PVA Membrane Pervaporation Separating N-butanol/H2O Solution

As a very important organic solvent and chemical raw material, n-butanol is extremely widely used, its requirement for our country is more and more, so people are more and more concerned about its production methods, traditional production method of n-butanol is fermentation, fermentation products are n-butanol, acetone and ethanol, but during the process of fermentation, concentration of n-butanol is generally low, moreover, n-butanol acts serious product inhibition role to fermentation, in order to solve this problem, consider adopting pervaporation to concentrate and separate n-butanol, reduce product inhibition to guarantee the succession of fermentation process. As a new method of membrane separation, pervaporation has many advantages that other separation methods can not compare, it is suitable for near-boiling or azeotrope that traditional distillation methods difficult to separate, so pervaporation has broad application prospects and potential development in the separation of n-butanol/aqueous solution at low concentration.First of all, pervaporation performance of PVA (polyvinyl alcohol) membrane is experimentally studied in n-butanol/water at low concentration, by changing operating conditions such as experimental temperature, feed concentration, downstream vacuum to study and explore pervaporation behavior of PVA. The results show that:With the increace of experimental temperature, permeation flux and separation factor both show increasing tendency, and separation factor reached the highest value at60℃; With the increasing of raw material concentration, permeation flux shows decreasing tendency, and separation factor first increases then decreases; With the increasing of downstream vacuum, permeation flux and separation factor both shows increasing tendency.Secondly, study pervaporation behavior of PVA in ethanol/water and acetone/water, The results show that:With the increasing of experimental operation temperature, permeation flux shows increasing tendency, for ethanol/water system, separation factor shows decreasing tendency; With the increasing of raw material concentration, for ethanol/water system, permeation flux increases firstly and then decreases, it reached maximum around55%, separation factor shows decreasing tendency, for acetone/water system, permeation flux and separation factor both show increasing tendency. Under operating conditions of feed concentration5%, downstream vacuum0.085Mpa, the order of permeation flux of the three system is: n-butanol>ethanol>acetone; the order of separation factor of the three system is: ethanol> n-butanol> acetone.Finally, study pervaporation behavior of n-butanol-ethanol-acetone-water system in the PVA membrane, the results show that with the increasing of experimental operation temperature, permeation flux and separation factor both show increasing tendency.