Convective flow adsorption of nickel ions in PVDF membrane embedded with multi-walled carbon nanotubes and PAA coating

In this paper, convective flow adsorptive membrane for removal of low nickel concentration from water by introducing raw or functionalized multi-walled carbon nanotubes (MWCNTs) to pores of microfiltration membrane was prepared. For filling inter-CNT gaps, in situ polymerization of acrylic acid as monomer and ethylene glycol as crosslinker was employed. By pH increment, the adsorption of nickel was improved. This was explained by the changes in the surface charge of MWCNT and degree of nickel ionization. Oxidized MWCNT exhibited superior rejection of nickel ions due to the available functional groups and appropriate dispersion. By in situ polymerization of virgin membrane, and due to the filling of pores, microfiltration membrane was converted to ultrafiltration membrane with lower flux and higher rejection. The latter is partly due to presence of adsorption groups of oxidized MWCNT, sodium dodecyl sulfate (SDS) and functional group of polyacrylic acid in the pores. Moreover, static adsorption of membranes were investigated. (C) 2011 Elsevier B.V. All rights reserved.