Interaction of inert gases with ionic melts. Solubility of He, Ar, N2, O2 and CH4 in the (Na,K)NO3 eutectic solvent

Abstract

The solubility of He, Ar, N₂, O₂ and CH₄ was determined in the (Na,K)NO₃ equimolar mixture by using a high-sensitivity manometric technique. The experimental findings are in agreement with the general trends valid in the case of weak solute-solvent interactions: positive heat of solution and solubilities inversely proportional to molecular size of the solute gases. For instance at 533 K the solubility constants are: 3.5 × 10^–8, 1.3 × 10^–8, 1.0 × 10^–8, 0.97 × 10^–8, 0.88 × 10^–8 mol cm^–3 bar^–1 for He, Ar, O₂, CH₄ and N₂ respectively. For the various systems the ΔH values range between 16.5 and 18.5 kJ mol^–1 in the temperature interval 500–600 K. All the results are discussed in terms of the Uhlig-Blander solubility model.