Interactions of the Bismuthate Anion with Alkali, Alkaline Earth, Lanthanide, and Actinide Metals in Nitric Acid Systems

Abstract

The solubility, dissolution, and degradation of the bismuthate anion were studied in the presence of various metal ions. A molar extinction coefficient of the bismuthate species of 11.1 ± 0.2 L mol −1 cm −1 at 527 nm was determined through modified iodometric titration methods. The dissolution rate of solid NaBiO 3 was increased in the presence of smaller cations, presumably resulting from a decrease in steric hindrance during the ion-exchange reaction with Na + . Increasing the charge of the ions in solution, however, increased the stability of BiO 3 − in solution, reducing the rate of degradation from Bi(V) to Bi(III) with a near linear correlation as a function of countercation charge. The presence of U(VI), as UO 2 2+ , increased the BiO 3 − equilibrium concentration and resulted in notable changes of the BiO 3 − absorbance band, indicating an interaction between the uranyl cation and bismuthate anion.