polysulfone/carbon nanotubes asymmetric nanocomposite membranes: effect of nanotubes surface modification on morphology and water permeability

Polysulfone/carbon nanotubes (psf/cnts) nanocomposite membrane wasprepared via phase inversion induced by immersion precipitation technique.in addition, the surface of the cnts was functionalized by polar carboxylicand amine groups to improve the interaction between the cnts and thepolymer matrix. for this purpose, the neat cnts were chemically treatedusing sulfuric acid/nitric acid (h2so4/hno3) mixture and an aromatic amineagent, i.e. 1-4-diamino benzene (dabz), to produce the functional groups onthe cnts surface. the fourier transform infrared (ftir) spectra indicatedthe presence of carboxylic- and amine-functional groups on the nanotubessurface. asymmetric psf composite membrane with various levels of thefunctionalized cnts were prepared to investigate the effect of functionalgroup type on the morphology and water flux rate of the resultingmembranes. the results showed that the incorporation of the functionalizedcnts up to 0.5 wt% increased the pore size and surface roughness of thesheet membranes, while further addition decreased porosity and roughness.higher water flux rate was observed for the amine-functionalized cnts (afcnts) reinforced psf membrane when compared with the membranesreinforced with the carboxyl-functionalized cnts (cf-cnts). the strongercompatibility between af-cnts and the psf matrix caused higher waterpermeability. the salt rejection performance of these microfiltrationcomposite membranes was evaluated.