| Ethyl acetate is widely used in various industrial solvents.At present,the production of ethyl acetate in China is usually synthesized by direct esterification of acetic acid and ethanol.However,a small amount of water will be contained in the crude product of ethyl acetate,which will affect the quality of the product and reduce the stability of ethyl acetate.Therefore,it is necessary to remove a small amount of water from ethyl acetate.Pervaporation membrane separation technology is very suitable for the separation of trace moisture in organic matter because of its good separation performance,low energy consumption,no pollution to the environment and no need of entrainer.If pervaporation membrane separation technology is applied to ethyl acetate dehydration,the production cost and energy consumption of ethyl acetate can be reduced.In this work,ZSM-5 zeolites and COF SNW-1 as modifiers were filled into the PVA membrane matrix.The PVA/SNW-1 and PVA/ZSM-5 hybrid membranes were prepared by casting scraping method.The morphology,element distribution,physicochemical properties,thermal stability and hydrophilicity of the membrane materials were characterized by SEM,EDS,FTIR,XRD,TG,WCA,AFM,mechanical properties test and solubility parameter calculation.The equilibrium swelling experiment was used to investigate the swelling properties of membrane materials in different solutions.The effects of filler content,feed concentration and feed temperature on the performance of the hybrid membrane were investigated by pervaporation.The results showed that ZSM-5 particles were closely combined with PVA membrane matrix and were dispersed evenly.In addition to the hydrophilic property of ZSM-5,there was hydrogen bond interaction between ZSM-5 and PVA,but there was no chemical interaction between ZSM-5 and PVA.The swelling experiment showed that the water affinity of the hybrid membrane was much stronger than that of ethyl acetate.In addition,the group contribution method was used to calculate the solubility parameters of each component to predict the affinity between ethyl acetate,water and hybrid membrane materials.Pervaporation experiments showed that with the increase of feed concentration,the permeate flux increased,while the separation factor decreased.With the increase of feed temperature,both the permeate flux and separation factor increased.With the increase of ZSM-5 filling amount,the permeate flux and separation factor increased at first and then decreased.When the ZSM-5 was 6wt%,the permeation flux and separation factor reached the maximum,which were 1231 g·m-2·h-1and 6072,respectively.The results of characterization of PVA/SNW-1 hybrid films showed that there was no gap between the SNW-1 nanoparticles and the PVA membrane matrix and agglomerations appear when the filling amount reached 9 wt%.The addition of SNW-1 enhanced the mechanical strength,thermal stability and hydrophilicity of the hybrid membrane.The swelling degree of PVA/SNW-1hybrid membrane in water was much higher than that in ethyl acetate,indicating that the hybrid membrane had preferential adsorption performance for water.When the feed water concentration was 4 wt%and the temperature was 30℃,with the increase of SNW-1 filling amount,the permeation flux and separation factor increased first and then decreased.When the SNW-1 filling amount was 9wt%,the separation index reaches the maximum,and the permeation flux and separation factor were 1337 g·m-2·h-1and 7783 respectively.When the temperature was 30℃,with the increase of feed concentration,the permeation flux increased and the separation factor decreased.When the feed water concentration was 4 wt%,with the increase of feed temperature,the permeation flux and separation factor also increased,the maximum permeation flux and separation factor were 2294 g·m-2·h-1and 9079,respectively.This study provided the necessary basic data and theoretical basis for the industrial application of pervaporation technology. |
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