Investigation and prediction of the salting-out effect of methane in various aqueous electrolyte solutions

• Salting-out effect of various electrolytes on the solubility of methane in aqueous solution was investigated.
• Ions with larger charge density exhibited stronger salting-out effect.
• Scaled particle theory was employed to corroborate the experimental data.

The maximum solubility of methane was determined in aqueous solution of Al2(SO4)3, MgSO4, K2SO4, Na2SO4, AlCl3, MgCl2, KCl, NaCl, MgBr2, KBr, and NaBr with various concentration (1, 3 and 5 wt%) at ambient pressure. Salting-out effect was observed in all electrolyte solutions, exhibiting lower solubility of methane compared to that in pure water. In general, electrolyte solutions comprising cations/anions with high charge valency and small ionic radius exhibited stronger salting-out effect due to large charge density of the corresponding ions. Furthermore, anions exhibited larger influence on the degree of salting-out compared to cations. Scaled particle theory was employed to corroborate the trend of the experimental solubility of methane in electrolyte solutions.

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