engleski

Cathodic stripping square wave voltammetry of Cu(II)-oxine complexes. A mechanistic study

The reaction mechanism for the reduction of Cu(II)-oxine complexes on mercury electrodes is studied by cyclic voltammetry (CV) and square-wave voltammetry SWV). The quasi-reversible two- electrontransfer is analysed from a theoretical point of view according to the EEd and EdE mechanistic schemes based on an nalysis of the Butler-Volmer formalism. The effects of SWV parameters and solution composition are analysed. Fitting experimental data with theoretical curves allowed to evalution of charge transfer rate constants, as well as discrimunation between adsorbed or soluble species. In buffered solution at pH 7.7, a ks value of 0.8 s-1 was determined, for a one-step process involving adsorbed reactants and soluble product. In unbuffered solutions, a split in the redox wave is observed with ks values of 60 and 4 s-1 for each process, assigned to the reduction of CuOx+ and Cu(Ox)2, respectively.

copper ; oxine ; square-wave voltammetry ; adsorption ; mercury electrode

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