Facilitated Ion Transfer Across the Membrane Interface Between Two Immiscible Electrolyte Solutions
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Date
1993-06
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Publisher
Addis Ababa Universty
Abstract
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).
Description
Keywords
Electrolyte Solutions