Solubility of oxygen in aqueous electrolyte solutions

The solubility of oxygen in a number of aqueous electrolyte solutions was determined using a colorimetric method based on the oxidation of indigo carmine. The effects of changes in electrolyte concentration, temperature and partial pressure of oxygen were investigated. The ratio of the solubility of oxygen in the electrolyte solutions to that in pure water decreases as the concentration of the electrolyte increases but is essentially independent of both temperature (over the range 298–348 K) and the oxygen partial pressure (over the range 0.1–1.0 atm). Empirical relationships for this solubility ratio as a function of the electrolyte concentration and temperature were developed. The predictions made using these relationships are found to be superior to the alternative methods suggested in the literature, particularly for those conditions frequently found in hydrometallurgical systems, namely at high electrolyte concentrations. The significance of changes in the solubility of oxygen in aqueous electrolyte solutions is briefly discussed with particular reference to the hydrometallurgical implications.