Creation of water-permeation pathways with matrix-polymer functionalized carbon nanotubes in polymeric membranes for pervaporation desalination

Abstract

Membrane-based pervaporation desalination is an effective process for freshwater resource and treatments on waste brines. Both water permeation fluxes and salt rejection are concerned for the membrane-based desalination. In this work an effective approach to increase the water permeation fluxes of the pervaporation desalination membranes has been demonstrated through utilization of matrix-polymer functionalized carbon nanotubes in creation of water permeation pathways in the membranes. With poly(vinyl alcohol) (PVA) as the matrix polymer for membrane fabrication, a small amount of PVA-functionalized CNTs (0.06 wt%) effectively increases the water permeation fluxes of the PVA membranes from 1,630 to 6,140 gm⁻²h⁻¹ (feeding solution: 3.5 wt% NaCl_(aq) at 25 °C) without sacrifice of salt rejection, corresponding to a 3.77-times of increase in water permeation flux. The membrane is also workable on concentrated salt aqueous solution (15 wt% NaCl_(aq)). The approach has the potential to be employed to other polymer membranes for pervaporation separation.