Enhanced removal of Cr(VI) by polymer inclusion membrane based on poly(vinylidene fluoride) and Aliquat 336

Abstract New polymer inclusion membranes (PIMs) based on poly(vinylidene fluoride) (PVDF) (polymer matrix), tricaprylmethylammonium chloride (Aliquat 336) (ion carrier) and 2-nitrophenyloctylether (2NPOE) (plasticizer) were successfully elaborated by casting evaporation method and used in selectively facilitated transport of Cr(VI) ions in an acidic aqueous medium. Obtained PIMs are dense and homogeneous and are characterized by intermolecular interactions of the membrane components (i.e. polymer matrix, ion carrier and plasticizer). The presence of ion carrier and plasticizer enhances the membrane flexibility and its hydrophilic character. The decrease of the PVDF melting point is ascribed to the strong electrostatic interactions between liquid compounds (i.e. ion carrier and plasticizer) and polymer chains. PVDF-based PIM with only 20 wt.% of Aliquat 336 ensures almost complete transport of Cr(VI) ions from the donor to acceptor phase. Moreover, the addition of 5 wt.% of plasticizer significantly increases the transport flux. Also, Cr(VI) ions are selectively recovered (∼97%) from a mixture containing other heavy metal ions (Cd(II), Pb(II), Fe(III), Zn(II), Cu (II), Ni(II), Co(II)) with such PIM. Elaborated PVDF-based PIMs reveal improved transport properties compared to other polymer-based PIMs, exhibiting high stability (more than 190h) and lifetime durability and so they are suitable for long term application.