Composite membranes comprising of polyvinylamine-poly(vinyl alcohol) incorporated with carbon nanotubes for dehydration of ethylene glycol by pervaporation

Composite membranes comprising of a separating layer of polyvinylamine (PVAm)-poly(vinyl alcohol) (PVA) incorporated with carbon nanotubes (CNTs) supported on a microporous polysulfone substrate were fabricated for the dehydration of ethylene glycol by pervaporation. The material aspects of the membranes were characterized with Fourier transform infrared (FTIR), Raman spectroscopy, X-ray diffraction (XRD), contact angle measurement and water sorption uptake, using dense films of PVAm-PVA/CNTs, to determine the effects of CNTs on the intermolecular interactions, degree of crystallinity, surface hydrophilicity, and degrees of swelling of the PVAm-PVA/CNT membranes. The effects of feed water concentration, temperature and CNT content in the membrane on the separation performance were investigated. The incorporation of CNTs into the membrane was shown to increase the permeation flux and separation factor, and the improvement in the separation performance was particularly significant at low feed water concentrations. At a feed water concentration of 1 wt%, a permeation flux of 146 g/(m2 h) and a separation factor of 1160 were achieved at 70 °C using a PVAm-PVA/CNT membrane containing 2 wt% of CNTs.