DC Polarographic and Plane Polarographic investigation of the reduction of Thallium(I) - Aqueous systems at dropping mercury electrode

The reduction behavior Thallium (I) at DME has been studied by several authors with different equivalent circuits and arrived at varying results. The complexity is due to the rapid reduction process and the adsorption behavior in the mercury solution interface. So, a thorough investigation was carried out on the reduction behavior of Thallium(I) at DME using DC polarographic and impedance methods assuming Randles and Laitinen (1955) basic equivalent circuit to hold good. The investigation was carried out in three different supporting electrolytes, sodium perchlorate, potassium nitrate and potassium chloride and for four different concentrations of depolariser. The double layer capacity was obtained by extrapolation method for all the systems. The reactant adsorption was established in the supporting electrolytes, potassium nitrate and potassium chloride. In the case of sodium perchlorate a different behavior was observed. Further theoretical phase sensitive ac polarograms are drawn to confirm the results. In all the systems, Thallium (I) proceeds with high degree of reversibility and the values of Ksh were found to be greater than one.