Estimation of Interface Energy of 'Metal Oxide/Ionic Melt' System from Data on Lead Oxide Solubility in Molten Kcl-Nacl Eutectic

Solubility and dissociation constants of PbO in molten KCl-NaCl eutectic at 700 °C were determined by sequential addition method. PbO was stated to be a weak base, pK=3.50± 0.07. E -pm plot possessed anomalous behaviour in the vicinity of the saturation point, that was explained by the partial dissolution of PbO powder resulting in the decrease of PbO particle sizes and in the increase of PbO surface square. On the basis of the Ostwald-Freundlich equation the interface energy of PbO/KCl-NaCl system was estimated to be 56 J -m. This allowed to estimate sizes of PbO particles formed at the potentiometric determination of PbO solubility in molten KCl-NaCl.