Potential step voltammetry of ion-transfer at liquid/liquid interface with preceding chemical reaction. Determination of the rate and equilibrium constants from voltammetric curves

Theoretical equations of the potential step voltammograms for the ion-transfer with preceding chemical reaction have been derived. Results were applied to analyze the voltammetric behavior of 1,4,7,10,13,16-hexathiacyclooctadecane-assisted transfer of Pb2+ ion across the nitrobenzene/water interface from aqueous medium containing citrate(3-) ion. The dissociation and association rate constants and the equilibrium constant of Pb2+-citrate(3-) complex in aqueous medium are determined to be 1.2x10(4) s(-1) and 1.2x10(10) M-1 s(-1) and 10(6.0) M-1, respectively. The results are compared with those obtained by potential sweep voltammetry.