Effect of Multi-walled Carbon Nanotubes on Pervaporation Characteristics of Chitosan Membrane

Abstract

Nanocomposites are endowed with the ability to exhibit properties that substantially differ from those of the neat polymer. They tend to be useful for molecular separations, including chemical separation and bioseparation. Novel nanocomposite membranes were prepared through the induction of multi-walled carbon nanotubes (MWNT) into chitosan biopolymer (CS). To further explore the intrinsic correlation between pervaporation performance and free volume characteristics, a molecular dynamics simulation was first performed, in order to qualitatively analyze the contribution of MWNT incorporation on improving free volume characteristics of the nanocomposite membranes. Secondly, the pervaporation performance of CS–MWNT nanocomposite membranes was evaluated with respect to permeation flux and selectivity under varying operating conditions. The membranes cross-linked with glutaraldehyde, were tested for the separation of an isopropanol (IPA)/water azeotropic mixture (87.5% IPA) at 30°C and found to exhibit permeation flux and selectivity of 0.09 kg/(m2 h) and 55.8, respectively, for neat chitosan polymer. The corresponding values for CS with 0.4% MWNT incorporated were observed to be 0.50 kg/(m2 h) and 296.2, respectively. To further explain the simultaneous increase of permeation flux and selectivity, the membranes were characterized by Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy and thermogravimetric analysis.