Experimental evidence for the adsorption-desorption phenomenon on the spectroscopy impedance measurements of an electrolytic cell

The frequency dependence of the real and imaginary parts of the electrical impedance of an electrolytic cell in the low frequency range is experimentally investigated. We show that a possible candidate able to explain the anomalous increasing of the real part of the electrical impedance of the cell is the adsorption-desorption phenomenon at the bounding surfaces. Measurements are performed on cells of water solution containing KCl, of different thickness and concentration of KCl, limited by the same type of gold electrodes. The experimental data can be fitted with the same adsorption and desorption coefficients, appearing in the kinetic equations, in the Langmuir approximation. This result confirm that the electrical impedance of the interface introduced to interpret the observed increasing of the resistance of the cell, in the low frequency region, could be connected with the adsorption-desorption phenomenon.