SOLUBILITY OF SODIUM-CHLORIDE AND SULFATE IN SUBCRITICAL AND SUPERCRITICAL WATER-VAPOR FROM 450-550-DEGREES-C AND 100-250 BAR

The solubility of sodium chloride in water vapor has been determined at supercritical temperatures ranging from 450-550-degrees-C and sub- and supercritical pressures varying from 100-250 bar. Measured sodium chloride concentrations ranged from 0.9-101 ppm (by weight). In the experiments, water vapor was saturated by continuously flowing it through a tube packed with solid salt. The results for sodium chloride agreed well with other studies which used continuous flow methods. Hydrolysis of the solid salt was found as a possible explanation for some of the reported discrepancies in the literature. Experiments with sodium sulfate at 500-degrees-C and 250 bar were also performed. Measured sodium sulfate concentrations were around 0.9 ppm, and exhibited unsteady behavior. Though only an estimate of Na2SO4 solubility could be obtained, this value was over two orders of magnitude lower than that for sodium chloride at identical conditions.