Development of ion imprinted technique for designing nickel ion selective membrane

An ion imprinted membrane with a porous polyvinylidene fluoride (PVDF) support was prepared by surface ionic imprinting technology. Ion imprinted membranes possess artificial recognition sites, which are able to specifically rebind a target ion in the presence of other similar compounds. In this study, Ni(II) ion imprinted membrane (IIM) was synthesized by copolymerization of Ni(II) ion (or without it for non-imprinted membrane) and dithizone as chelating ligand in the presence of methacrylic acid (MAA), ethyleneglycol dimethacrylate (EGDMA) as monomer and cross-linker, respectively using 2,2-azobisisobutyronitrile (AIBN) as initiator. Dithizone was selected as complex agent to show the capability of using a non-special ligand for synthesis of selective ion imprinted membrane. The affecting parameter such as pH and concentration of Ni²⁺ ion solution on the loading capacity of membrane were investigated. To obtain the maximum adsorption efficiency of Ni, pH of the sample solution should be carefully adjusted at 8. In addition, the effect of imprinting technique on the selective recognition of Ni(II) ion towards Co(II) ions through the modified imprinted membrane was studied in the permeation experiments. The results of permeation and adsorption experiment indicated that, the Ni(II) ion imprinted membrane has the ability of specificity and recognition towards the imprinted nickel ion compared to the non-imprinted polymer membrane. The separation factor (α) of the imprinted membrane for the Ni²⁺ ion versus Co²⁺ ions was 2.6, whereas the non-imprinted and control membrane (without dithizone ligand) did not show any selectivity.