Enhanced desalination performance of poly (vinyl alcohol)/carbon nanotube composite pervaporation membranes via interfacial engineering

In this study, poly (vinyl alcohol) (PVA) based mixed matrix membranes containing multiwalled carbon nanotubes (MWCNTs) or carboxylic multiwalled carbon nanotubes (C-MWCNTs) were produced via interfacial adhesion, hydrogen bonding or covalent bonding. The desalination performances of the synthesized membranes were compared by the pervaporation (PV) process. A PVA membrane crosslinked with maleic acid (MA) was also prepared for comparison. FESEM and TEM images indicated that the C-MWCNTs were disentangled and dispersed uniformly in the PVA matrix whereas MWCNTs without functional groups readily aggregated. The incorporation of CNTs endowed the PVA/CNT membranes with improved thermal stability, which was confirmed using TGA and DSC measurements. In particular, the altered properties of the PVA/CNT composites enhanced the separation performance compared with the PVA membrane without CNTs. The performance tests showed that the PVA/CNT composite membranes featured remarkably larger water fluxes than control PVA/MA membrane (38.8%–154.1% increase) while maintaining high salt rejection. Thereinto, the overall best performance of 99.91% of salt rejection and 6.96 kg/m2 h of water flux at room temperature (22 °C) was obtained by the PVA/C-MWCNT/MA membrane (19 ± 1 μm thickness) when the feed was synthetic NaCl solution of 35,000 ppm. Kinetic desorption method was applied to compare salt transport properties of the resultant PVA/CNT composite membranes. The salt transp...
Source: Journal of Membrane Science - Category: Materials Science Source Type: research