Preparation Of Filled Modified PDMS Pervaporation Membrane And Separation Performance For Ester/water

n-Butyl acetate and ethyl acetate are commonly used in the preparation of pharmaceuticals,acrylic resins,nitrocellulose,plastics,cosmetics,and perfumes.They are conventionally synthesized by esterification reaction in industrial;the wastewater discharged from the process contains trace amounts of n-butyl acetate and ethyl acetate,which need to be recycled for safe discharge.Compared with traditional separation methods,pervaporation is superior in terms of energy-saving,simple operation,environmental friendliness and high separation efficiency.It is widely used in petrochemical,environmental protection,pharmaceutical and other related industries in the dehydration of organic solvents or the removal of organic matter in wastewater.In this paper,the novel octaphenyl-polyhedral oligomeric silsesquioxane(OP-POSS)and ZSM-5 zeolite were used to modify the polydimethylsiloxane(PDMS)material with polyvinylidene fluoride(PVDF)as the support layer;the PDMS/OP-POSS/PVDF and PDMS/ZSM-5/PVDF hybrid membranes were prepared by coating.The physciochemical properties of membranes were characterized by scanning electron microscopy,contact angel,Fourier transform infra-red,X-ray diffraction and thermogravimetric analysis.The swelling behavior and pervaporation performance of the membrane material were also investigated.The characterization results show that OP-POSS and ZSM-5 are uniformly dispersed in the PDMS film,and no chemical change occurred between the modifiers and PDMS polymer chain.The hydrophobic and thermal stability properties of the filled film were obviously improved by incorporation of OP-POSS and ZSM-5.The equilibrium swelling experiment showed that OP-POSS and ZSM-5 improved affinity of hybrid membranes towards n-butyl acetate and ethyl acetate.The hybrid membrane has a stronger affinity for n-butyl acetate than ethyl acetate.The dynamic swelling analysis showed that the diffusion rate of n-butyl acetate through the hybrid membranes was significantly lower than that of ethyl acetate.In addition,the solubility parameter of each component was calculated by the group contribution method to predict the affinity of hybrid membranes towards n-butyl acetate and ethyl acetate.The results are consistent with the equilibrium swelling experiment.The effects of OP-POSS and ZSM-5 contents,feed concentration and temperature on membrane performance were investigated through pervaporation experiments.With the increase of OP-POSS and ZSM-5 content in the hybrid membranes,the permeate flux increased significantly,and the separation factor increased sharply and then decreased.For the effects of feed concentration and temperature,hybrid membranes showed a similar trend of increasing permeation flux and the separation factor increased first and then decreased.For n-butyl acetate/water systems,the permeate flux and maximum separation factor of PDMS/OP-POSS/PVDF hybrid membrane were 348 g·m-2·h-1 and 221 and these for PDMS/ZSM-5/PVDF hybrid membrane were 319 g·m-2·h-1 and 131.For ethyl acetate/water systems,the permeate flux and maximum separation factor of PDMS/OP-POSS/PVDF hybrid membrane were 1694 g·m-2·h-1 and 137,and these for PDMS/ZSM-5/PVDF hybrid membrane were 1385 g·m-2·h-1 and 121,respectively.