High pressure differential scanning calorimetry of the hydrothermal salt solutions K2SO4-Na2SO4-H 2O and K2HPO4-H2O

Abstract

Aqueous salt solutions under hydrothermal conditions play an important role in geochemistry as well as in processes using hot compressed water as the process medium such as supercritical water oxidation (SCWO) and supercritical water gasification (SCWG). Isochoric high pressure differential scanning calorimetry (HP-DSC) was used as an accurate technique to investigate the phase behavior of such solutions under hydrothermal conditions. New data in the low concentration range (0.14-15.0 mass%) has been collected for the binary systems K2SO4-H2O, Na2SO4-H 2O and K2HPO4-H2O. Furthermore we have discovered a liquid-liquid immiscibility in the ternary system K 2SO4-Na2SO4-H2O, which has not been reported before. © 2013 The Royal Society of Chemistry.