Modeling approaches to hydration properties of aqueous nonelectrolytes at elevated temperatures and pressures

Thermodynamic models describing temperature and pressure evolution of Henry's law constant and related properties of hydration of aqueous nonelectrolyte solutes are reviewed. The included models cover a broad range spanning from simple van't Hoff-like equations used in environmental chemistry over the more elaborate empirical or semiempirical temperature correlations favored for engineering purposes to complete equations-of-state for hydration properties originating in the theory of near-critical phenomena and developed for modeling of hydrothermal systems. For aqueous organic solutes, the methods are often coupled with the group additivity approximation, leading to complex tools for predicting the properties of solutions containing organic species. The various models were subjected to tests documenting their expected range of applicability at elevated pressures ( for acid gases) or at high temperatures ( for hydrocarbons and oxygen-containing organic solutes). New developments in the field are discussed and some future needs are envisioned.