Electrochemical reduction of lead chloride on some solid electrodes in fused NaCl-KCl mixtures

Abstract

The electrochemical reduction of PbCl₂ has been studied in a fused NaCl−KCl mixture with tungsten, molybdenum and nickel electrodes. Experiments were conducted in the 700–850°C temperature range using voltammetric and chronopotentiometric techniques. Poor lead adhesion to the electrode surface made the study with the nickel electrode impossible and the results obtained with the tungsten electrode somewhat doubtful. Lead adhesion to the molybdenum surface was good but the experimental curves had to be corrected for a cathodic residual current. The lead chloride reduction appears to occur reversibly according to the reaction.

$$PbCl2 + 2e^ - \to Pb + 2Cl^ - $$

No evidence of lead metal solubility in the melt was found. The lead ion diffusion coefficient obeys the Arrhenius Law:

$$D_{Pb\left( {II} \right)} = 10^{ - 3} \exp \left( {{{ - 2957} \mathord{\left/ {\vphantom {{ - 2957} T}} \right. \kern-\nulldelimiterspace} T}} \right)cm^2 s^{ - 1} $$

in the temperature range 700 to 850°C.