Industrial & Engineering Chemistry Research, Vol.47, No.15, 5112-5118, 2008
Influence of a single salt (NaCl/Na2SO4) on the solubility of ammonia in liquid mixtures of (water plus methanol)
New experimental results are reported for the influence of two single salts (sodium chloride and sodium sulfate) on the solubility of ammonia in liquid mixtures of water and methanol at 353 and 393 K. The mole fractions of methanol in the (gas-free and salt-free) solvent mixture of water and methanol were about 0.25, 0.5, and 0.75 in the experiments with sodium chloride and about 0.05 and 0.25 in the experiments with sodium sulfate. The molality of the salt varied between about 0.25 and 2 (0.15 and 1) mol/kg of the solvent mixture in the systems with sodium chloride (sodium sulfate). The maximum molality of ammonia was about 6.7 mol/kg of (water + methanol) for both temperatures and for both salts. The maximum total pressure above the liquid solutions was about 0.3 MPa (1 MPa) in the system containing sodium chloride at 353 K (393 K) and about 0.2 MPa (0.7 MPa) in the system with sodium sulfate at 353 K (393 K). The experimental results are used to test a thermodynamic framework which allows the influence of both single strong electrolytes on the solubility of ammonia in liquid mixtures of water and methanol to be predicted. The prediction results are in good agreement with the new experimental data.