An equation of state for predicting the thermodynamic properties and vapour–liquid partitioning of aqueous Ge(OH)4 in a wide range of water densities

Correlation and prediction of thermodynamic properties of nonelectrolytes at infinite dilution in water over very wide temperature and pressure ranges (2000K and 10GPa)

“…These solutes may easily change their speciation with water densities. For example, the analysis performed in (Akinfiev and Plyasunov, 2013, 2014, Akinfiev et al, 2015 showed that while for hydroxides of metalloids (B(OH) 3 , As(OH) 3 , Si(OH) 4 , Ge(OH) 4 , MoO 2 (OH) 2 ) a sin- gle form dominates speciation from the gas-like to liquid-like water densities, then for hydroxides of metals (Cu(I) and Zn(II) were considered as examples) the situation is more complicated: at gaseous water densities and/or high temperatures simple hydroxides like CuOH and Zn(OH) 2 may be the main form of metals, and with the increase of q à 1 these forms undergo the hydration with the formation of hydrates of hydroxides from CuOHÁ(H 2 O) to CuOHÁ(H 2 O) 3 and from Zn(OH) 2 Á(H 2 O) to Zn(OH) 2 Á (H 2 O) 4 , with the shares of hydrated forms increasing with the water density and decreasing with the raising temperature. In the silica-water system, even at moderate silica concentrations, in addition to the monomer Si(OH) 4 , the dimer Si 2 O(OH) 6 and higher polymers may form (Zotov and Keppler, 2002;Newton and Manning, 2003;Mysen, 2010;Mysen et al, 2013), particularly when approaching the upper critical point of the binary SiO 2 -H 2 O system (Newton and Manning, 2008).…”

Predicting Solubility of Oxides of Metals and Metalloids in Supercritical Water

“…Based on limited available data for fugacity coefficients of B­(OH) 3 and Si­(OH) 4 in steam, an empirical method of estimation of φ 2 ∞ for the hydroxide species in steam at ρ 1 * < 250 kg m –3 was proposed, and it will be discussed below. Thermodynamic properties of a number of dissolved hydroxides (Si­(OH) 4 , B­(OH) 3 , As­(OH) 3 , Ge­(OH) 4 ) have been correlated up to high T and P using the Akinviev–Diamond equation of state (EoS), which originally was proposed for gases in water. However, this EoS was shown , to underpredict the infinite dilution fugacity coefficients at extrapolation to 1000 K and above, at least for gases (Ar, H 2 , CO 2 , NH 3 ), particularly at high pressures/water densities.…”