Nanostructural Engineering of Electrospun Poly(vinyl alcohol)/Carbon Nanotube Mats into Dense Films for Alcohol Dehydration

Pervaporation is a green process that consumes low energy and does not require solvents for separation. In this work, interfacial engineering of poly­(vinyl alcohol) (PVA)/carbon nanotube (CNT) electrospun fibers was attempted to fabricate dense membranes for pervaporation. Ethanol and water were used as nonsolvent and solvent, respectively, to alter the nanoscopic configuration of the fibers through interfacial solvent interactions. PVA and PVA/CNT mats with micron-sized pores (>100 μm) were prepared by optimizing electrospinning conditions. The mats were compacted via immersion in ethanol. They exhibited asymmetric close-packed top and bottom layers and porous intermediate layers. Further consolidation was achieved using water to fuse the fibers. The mats with more than 1.5 wt % CNT loading were stable against water owing to the cross-linking between CNTs and PVA. Because of the uniform dispersion of CNTs into the PVA matrix, the PVA/CNT dense films exhibited higher water/ethanol selectivity and water flux than those exhibited by similar films prepared by solution-casting. Thus, simple interfacial engineering of electrospun mats presented in this work successfully generates high-performance PVA/CNT membranes. A high alcohol dehydration performance and time-efficient membrane fabrication are achieved.