Review of selenium thermodynamic data

This report assesses the accuracy and completeness of available thermodynamic data on selenium. A review of experimental methods from published literature on selenium thermodynamic data focused on chemical reactions responsible for the formation of both aqueous complexes and solid phases of selenate, selenite, and selenide. The reviewer selected best data values, based on the methods used for estimating thermodynamic data. After inclusion of these values into the MINTEQ model, a validation study evaluated model performance for selenite and selenide solid phases. Lack of selenate data precluded model validation for this compound. The review furnished data on 22 aqueous complexes of selenite, 15 of selenide, and 17 of selenate, as well as 21 solid phases of selenite, 20 of selenide and 8 of selenate. These data proved inadequate to represent the formation of species in the solid phase. The validation study gave inconclusive predictions of selenite and selenide solubility and could not be used to assess the accuracy or completeness of the thermodynamic data.