Comparison of the pervaporation performance of various types of carbon nanotube-based nanocomposites in the dehydration of acetone

Abstract

The present work focuses on the functionalisation of multi-walled carbon nanotubes (MWCNTs) with poly(vinyl alcohol) (PVA) in order to improve the compatibility and dispersion of MWCNTs in a chitosan (CS) matrix. The resultant PVA–MWCNT/CS nanocomposite membranes were crosslinked with glutaraldehyde. Pervaporation performances of the resultant membranes in dehydration of acetone were evaluated in terms of water permeance and selectivity towards water. The water permeance of the crosslinked nanocomposite membrane increased while the selectivity decreased compared to the crosslinked pure CS membrane. In addition, the selectivity and water permeance of the crosslinked nanocomposite membrane decreased while the water permeation flux improved with increasing feed temperature. Furthermore, crosslinking of the membranes was found to improve the selectivity of the membranes but lower the water permeance. In another approach, PVA functionalised MWCNT was bulk aligned on the poly(vinylidene fluoride) (PVDF) membrane by a simple filtration method and further coated with CS to form a novel three-layer nanocomposite membrane. This membrane showed immense improvement on the water permeance and selectivity. Upon comparison, the three-layer nanocomposite membrane was found to demonstrate the best separation performance among the membranes described here. Furthermore, the three-layer nanocomposite membrane emerged as a potential solution to the trade-off problem often faced by pervaporation membranes.