Solubility of sodium chloride in superheated and supercritical water at 350-700°C and 25-250 bar

The solubility of sodium chloride was measured in superheated and supercritical water at 350-700°C and 25-250 bar corresponding to water densities of ρH2O = 0.007-0.111 g/cm3. The measured concentrations were 0.3-115 ppm for Na and 0.8-173 ppm for Cl. The results at 400-600°C were interpreted in terms of formation of a hydrated NaCl(f) fluid species according to the reaction, NaCl(s) + nH2O(f) = NaCl*nH2O(f) and the results were fitted to a solvation model to give, log⁡cNaCl(f) = 3.50log⁡ρH2O(f) - 904.97/T + 6.94 where cNaCl(f) is the solubility of sodium chloride expressed in ppm (by weight) based on the measured Na concentration, ρH2O(f) is the density of pure water in g/cm3 and T is the temperature in Kelvin. The model used data taken at 400-600°C and 50-250 bar. The Cl/Na molal ratio was typically close to ~1.0 at temperatures