The Synthesis Of NaA Membrane By Different Seeding Method And Pervaporation In Ethanol/Water Separation

The traditional separation techniques like distillation and VSP demonstrate growing disadvantages in separation azeotropic or mixture with close boiling point. However, pervaporation has been adopted by more and more people for liquid separation due to its simple operation, low requirement for temperature and pressure, low energy consumption. That is why pervaporation has become one of the most active area in membrane research. At the same time, inorganic membrane has been applied in the pervaporation most extensively for its advantage in thermal stability, mechanical stability, chemical stability。This research mainly concentrates on the synthesis of NaA zeolite membrane by different seeding method and its application in separation of Ethanol/Water system.This study uses silica gel and sodium alumina as silicon resource and Al resource to prepare the hydrothermal gel with certain mole composition. The NaA membrane is synthesized on the surface of porous α-Al2O3substrate. The effect of temperature, synthesis time, hydrothermal gel composition, hydrothermal synthesis time, and different seeding methods on the separation performance of NaA membrane prepared was studied in this thesis. The membrane synthesized is characterized by SEM and XRD, and its separation factor and permate flux are identified by pervaporation equipment designed by myself to test its separation performance.The optimal conditions for hydrothermal synthesis of membrane are identified by many experiments as follows:the mole composition of the gel Al2O3:SiO2:Na20: H2O=1:2:2:120,synthesized at temperature100℃, for4h, and the synthesis process is repeated for twice. When the other operation conditions are the same, among the several seeding method such as dip-seeding, rub-seeding, vacuum seeding, dip-rub-seeding, the NaA zeolite membrane prepared by dip-rub-seeding method demonstrates the best performance in appearance characterization and separation.This study investigates the effect of temperature and concentration of feed liquid on the separation performance, and finds that the separation factor declines and permeation flux increases with the increasing of temperature,while the separation factor increases first then declines and the permeation flux increases with the increase of water content in the feed liquid. It has been found out that the separation presents the best performance when the pervaporation is conducted at343k with the composition of feed liquid90wt%Ethanol, with separation factor6824and permeation flux1.40kg/(m2·h) respectively.