Determination of reaction rate between cathodically formed FeII-triethanolamine-complex and FeIII-hepta-d-gluconate complex by cyclic voltammetry

Electron transfer reactions between iron^II/III-complexes are of general interest for corrosion processes, biological processes and technical applications. The cathodic reduction of Fe^III-triethanolamine (TEA) complex to form the Fe^IITEA-form of the complex has been examined by cyclic voltammetry. In the presence of Fe^III-d-heptagluconate (HDGL), complex catalytic currents are observed due to homogenous chemical reaction between Fe^IITEA and Fe^III(HDGL)₂ which regenerates Fe^IIITEA. This method can be used to determine the rate constant of the redox reaction between Fe^IITEA and Fe^III(HDGL)₂ with $k_{\mathrm{f}}^{\prime }=88\pm 12{\mathrm{dm}}^3{\mathrm{mol}}^{-1}{\mathrm{s}}^{-1}$.