Electrochemical Behavior of Iron (II) at a Nafion-1, 10-phenanthroline-modified Carbon Paste Electrode: Assessing the Correlation between Preconcentration Potential, Surface Morphology and Impedance Measurements

Abstract

Using cyclic voltammetry, differential-pulse voltammetry, and impedance spectroscopy, the electrochemical behavior of a Nafion-1,10-phenanthroline-modified carbon paste electrode (CMCPE: Chemically Modified Carbon Paste Electrode) immersed in a supporting electrolyte 0.1 mol.L^-1 acetate buffer solution (pH 4.5) containing iron(II) metal ion was investigated. The optimal analytical parameters for determining iron(II) metal ions (preconcentration potential and time, pH, electrode rotation) have been evaluated and correlated with the surface morphology of the CMCPE surface, the surface chemical composition analysis, and the impedance measurements of the CMCPE immersed in the supporting electrolyte. The experimental impedance values were fitted to an equivalent circuit model using a simple methodology based on a redox polymer-modified electrode. It was shown that among various potentials used for iron(II) accumulation in the Nafion-film, the potential of +1.3 V vs. Ag/AgCl/3 mol. L^-1 KCl allowed a better differential-pulse determination of the examined iron(II) metal ion in the supporting electrolyte. With the determination of the iron(II) metal ion in groundwater samples collected in a community on the outskirts of Ouagadougou, the Capital of Burkina Faso, the research was expanded to real applications.