[Electrochemical-behavior of the Te(iv) Ion in Water-sodium Hydroxide Mixtures]

The electrochemical properties of the tellurite ion have been investigated in slightly hydrated molten NaOH at 350-degrees-C and in concentrated hydroxide solutions at NaOH mole fractions ranging from 0.05 to 0.6, the temperature range depending on the vapor pressure of the solvent. Voltammetric measurements were carried out at a platinum electrode. The TeO3(2-) ion reacts cathodically and anodically producing Te2- and TeO4(2-) ions respectively. Only the reduction peak was well defined and was thus chosen for the present study. Although the Te(IV)-Te(II) system exhibits a non-Nernstian behaviour, cyclic voltammograms were characterized by some anodic peaks whose number and configuration were depending on the basicity of the solvent. Adsorption processes and chemical formation of polytelluride ions were identified.