Thermodynamic data development: solubility method and future research needs (PLENARY)

The solubility method has been used for a long time. Many older published studies used inadequate procedures fraught with deficiencies/problems and resulted in much of the older solubility data being of poor quality. What is surprising however is that there are still articles currently appearing in print describing new studies wherein the most up-to-date procedures have not been used. Discussed herein are important procedures to quantify/control during the use of solubility method to obtain reliable thermodynamic data. These procedures include quantification of hydrogen ion, selection of redox agents to control particular oxidation states for redox sensitive elements such as actinides, and separation of solids from solutions for determining soluble concentrations. Also discussed are 1) ideal procedures/characteristics for conducting solubility studies or evaluating the older literature, 2) an example of how to use the evaluation criteria to judge the quality of older data, 3) some pitfalls in interpreting solubility data, and 4) examples of future research for which the solubility method is ideally suited.