Selective transport of metal ions across polymer inclusion membranes (PIMs) containing calix[4]resorcinarenes

Abstract The use of polymer inclusion membranes (PIMs) for selective and efficient transport of metal ions is increasingly retaining attention. We then prepared and characterized cellulose triacetate membranes doped with calix[4]resorcinarenes derivatives as fixed carriers and containing 2-nitrophenyl octanoate (2-NPOT) as a new synthetic plasticizer. We applied them for the investigation of facilitated transport of Zn(II), Cd(II), and Pb(II) ions from aqueous nitrate source phase ( c Me  = 0.01 M, pH 5.5). Influence of several parameters on metal ions transport were analyzed such as the pH of the receiving phase, the alkyl moieties of calix[4]resorcinarenes and the carrier content of the PIM. We specifically focused on the influence of the chemical nature of the plasticizer, 2-nitrophenyl octyl ether (2-NPOE) versus 2-NPOT, on metal ions transport as well as on long term stability and durability of the PIM membrane. We found that the facilitated transport of metal ions through our PIM proceeds through a carrier-mediated diffusion mechanism and relies on a pH-dependent driving force. Moreover, we revealed that NPOT containing PIM exhibited a significantly higher selectivity towards Pb(II) as well as a better membrane stability. These results may open news avenues in lead removal from waste waters.