Facilitated Ion Transfer Across the Membrane Interface Between Two Immiscible Electrolyte Solutions

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Addis Ababa Universty


The transfer of Ni2+, Cd2+ and Fe2+ facilitated by 2,2'bipyridine and Ni(bipY)32+ complex ion transfer across the membrane stabilized interface between two immiscible electrolyte solutions (water/nitrobenzene) was studied using the floW .. c).nj.e9tion technique, and dc 'i:~d . acc:iycHc vol tanuh~t:ry .t'7J~qff?how injection analysis the dependence of peak current height on the applied potential all, with the exception of Ni2+, showed an sshaped polarographic wave with fairly sharp i-t curves, indicating the reversible or diffusion controlled transfer of these ions. Ni2+ showed poor current-potential dependence with a hardly discernible half-wave potential. The i-t curve was very broad which shows that the transfer of Ni2+ is kinetically controlled. Similarly the ac cyclic voltammogram of Cd2+, Fe2+ and Ni (bipy) 3 2+ shoHed reversible behaviour with overlapping and reverse peak potentials and half-peak width of ~45 forward mv. In the ac cyclic voltammogram for the transfer of Ni2+ the peak potential for the forward and reverse scans did not overlap, indicating kinetically controlled transfer. The reversible transfer of the Ni (bipy) /+ complex was studied by single sweep voltammetry and the diffusion coefficient of the ion in water was evaluated. In the ac voltammetric experiment only the transfer of the bis and tris complex was within the range of the potential window. The transfer of Ni2+ and Fe2+ are presumed to be a complex ion transfer while that of Cd2+ appears to be a facilitated ion transfer of Cd2+ may occur in the bulk phase. The change in standard Gibbs energy of transfer between the successive complexes of Ni 2+ and Fe2+ was about 38.6 KJ/mol while that of Cd2+ was very large (53 KJ/mol).



Electrolyte Solutions