Mechanism of electrochemical solvent extraction of divalent metal ions with quinolin-8-ol

The transfer of divalent metal ions (M2+ = Mn2+, Co2+, Ni2+, Cu2+, Zn2+, Cd2+, Pb2+) facilitated by quinolin-8-ol (HQ) at the nitrobenzene-water interface was studied by polarographic and voltammetric techniques, In conflict with a proposed mechanism that assumes the interfacial transfer of a divalent complex ion [M(HQ)(2)(2+)], the observed current-potential curves showed characteristics similar to those of a reversible wave for monovalent-ion transfer, In this study, a new mechanism was proposed in which two monovalent ions (MQ(+) and H(2)Q(+)) are responsible for the ion-transfer current. The theoretical equation of the current-potential curve derived for the new mechanism was found to be useful for obtaining a better understanding of the ion-transfer processes.