Investigation of the Effect of the Support Layer on Pervaporation Performance of Supported Mixed Matrix Membranes in Separation of Water and Isopropanol

In this report, mixed matrix membranes which are supported by polyethersulfone and sulfonated polyethersulfone prepared for dehydration of isopropanol. The prepared membranes are composed of a porous sublayer from polyethersulfone/sulfonated polyethersulfone and a composite top layer of poly(vinyl alcohol) and titanate nanotubes. In fact, hydrothermally-synthesized titanate nanotubes are dispersed in poly(vinyl alcohol). Moreover, the sulfonated polyethersulfone are used to investigate the effects of the porous sublayer on mass transport and the separation performance of the membranes. Next, the ability of the prepared membranes were studied for pervaporation separation of 90 wt% aqueous isopropanol mixture at 50 . The obtained results indicate that the thickness and chemical properties of the support have had a significant influence on pervaporation results. Totally, decreasing the difference between hydrophilicity of top layer and support has resulted in formation of an ideal interface between the layers. Furthermore, the presence of sulfone groups in interface, formation of hydrogen bounds among hydroxyl groups of poly(vinyl alcohol) and sulfone groups of the sublayer are responsible for enhanced compatibility between the layers. As a result, selective separation of water through the membranes was obtained. In addition, the results indicated that the support led to existence of an additional mass transport in isopropanol dehydration as well as requiring the physical support for the resultant membranes. The obtained results showed that when 4 wt% titanate nanotubes were dispersed in poly(vinyl alcohol) which was supported by sulfonated polyethersulfone the flux and separation factor were about  0.29 kg/m2 h and 4828, respectively.