Improving the efficacy of PES-based mixed matrix membranes incorporated with citric acid–amylose-modified MWCNTs for HA removal from water

Abstract

Either difficulty of dispersion of carbon nanotubes (CNTs) in the solvent or low compatibility between polymeric chains of membrane and CNTs results in major drawbacks to using CNTs in the structure of mixed matrix membranes. CNTs’ functionalization has already gained increasing attention to overcome such problems. Herein, polyethersulfone-based mixed matrix membranes incorporated with citric acid–amylose-decorated multiwall carbon nanotubes (Am–MWCNTs–CA) were fabricated. These new synthesized nanoparticles and nanocomposite membranes were characterized by spectroscopic measurement methods such as IR spectroscopy, UV–Vis spectroscopy, 1H NMR spectroscopy, 13C NMR spectroscopy, water contact angle, attenuated total reflection-infrared, atomic force microscopy (AFM), and scanning electron microscopy (SEM). The pure water flux of the modified membrane incorporated with 0.5 w/v% Am–MWCNTs–CA increased over 130% in comparison with the unmodified membrane. Flux recovery ratio results illustrated that the membrane modified with 0.5 w/v% Am–MWCNTs–CA showed superior antifouling capacity of over 95.2%. SEM and AFM images showed significant and observable changes in surface morphology along with the formation of large finger-like macrovoids in the presence of Am–MWCNTs–CA. The presence of more COOH and OH functional groups on the surface of the modified membranes enforced the Donnan exclusion theory to reject rather divalent ions due to the migration of Am–MWCNTs–CA nanocomposite to the surface of membranes. In addition, humic acid removal capability of the prepared membranes was also calculated to be as high as 97.4% for the membrane embedded with 0.5 w/v% Am–MWCNTs–CA (M3).