Salt-specific effect on the solubility and aggregation of 1-butanol in water

The Hofmeister series is a classification of ions regarding their ability to stabilize or destabilize various types of solute molecules in water. In this study, we employ molecular dynamics simulations and C K-edge X-ray absorption spectroscopy to investigate how the solubility and aggregation of 1-butanol are affected by typical salting-out (SO2-4 2- 4 ), neutral (Cl-), - ), and salting-in (ClO-4 - 4 ) ions in the Hofmeister anion series. Both our computational and experimental results confirm that the addition of any of the three salts enhances the aggregation of 1-butanol, compared to pure water, manifesting a salting-out effect. The distance dependence of the salt effect on solubility and aggregation, calculated based on the Kirkwood-Buff theory, emphasizes that all hydration shells up to a distance of 1.2 nm have a crucial role in determining solubility and the degree of aggregation.