Thomasukutty Jose, Soney C George, Maya MG and Sabu Thomas
Novel PVA nanocomposite membranes were prepared with acid functionalized multiwalled carbon nanotubes (a-MWCNT) as the reinforcing material. The presence of functional groups on MWCNT is revealed by FTIR techniques. The excess swelling of poly (vinyl alcohol) (PVA) membranes were reduced by the crosslinking of glutraldehyde (GA). The functionalized MWCNT induces hydrophilicity to the PVA nanocomposites and the hydrophilic nature of the nanocomposites was revealed by the contact angle analysis. The effect of a-MWCNT concentration on the dielectric and DC conductivities of the PVA nanocomposites was studied very well. The electrical conductivity of the nanocomposites is increased with the concentration of MWCNT, and PVA with 1.5 wt% nanotube loaded membranes showed better dielectric properties. As the concentration of MWCNT increased to 1.5 wt%, the PVA nanocomposites got transformed from a region of insulator to semiconductor. DC conductivity also showed the same trend. The Voet model showed good agreement with the experimental results of the conductivity. We also found that the developed PVA/a-MWCNT nanocomposite membranes can be used to separate the azeotropic composition of water-ethanol mixtures. The pervaporation (PV) performance of the membranes is studied in terms of permeance and intrinsic selectivity. PVA with 0.5 wt% nanotube loaded nanocomposite membranes achieved 340% increment in intrinsic selectivity. The pervaporation performance of the membranes were in good agreement with the permeation ratio model, and the separation efficiency is influenced by the morphology of the membranes and the interaction of the filler and the permeates. It is also observed that the dielectric properties of the membranes were correlated with the concentration of the conductive nanofillers. Thus the present study provides good information on dielectric and the pervaporation performance of PVA/a-MWCNT nanocomposite membranes.