Solubility of hydrogen in aqueous solutions of sodium and potassium bicarbonate from 293 to 333 K

An experimental study is presented of the hydrogen solubility in aqueous salt solutions containing sodium and potassium bicarbonate from 293 to 333 K. For this purpose, gas consumption measurements have been performed by determining the ultimate pressure decrease in an intensively stirred, high pressure autoclave. Experiments were carried out at salt concentrations up to 1.0 mol kg-1. At higher salt molalities, the hydrogen solubility was too low to be measured reliably. It was demonstrated that the hydrogen solubility followed the well-known Sechenov salt concentration dependence. At 298 K, the Sechenov or salting-out parameters were equal to 0.41 and 0.32 kg mol-1 for sodium and potassium bicarbonate, respectively. Fairly good agreement was obtained with the salting-out parameters predicted by a recently developed empirical estimation method. The concentration ratio of the bicarbonate and carbonate ions showed only a minor influence on the hydrogen solubility. Furthermore, the Sechenov parameter was found to be a weak function of temperature. Virtually the same, linear temperature dependence was observed for both bicarbonate salts studied, i.e. −0.0023 and −0.0024 kg mol-1 K-1 for sodium and potassium bicarbonate, respectively.