Assessing the hydrotropic effect in the presence of electrolytes: competition between solute salting-out and salt-induced hydrotrope aggregation
Afonso C. Martins, Jordana Benfica, Germán Pérez‐Sánchez, Seishi Shimizu, Tânia E. Sintra, Nicolas Schaeffer, João A. P. Coutinho
Abstract
H-NMR analysis indicates that hydrotrope-solute interactions present a degree of site-specificity. The addition of chloride salts in the presence of higher IL concentrations promotes a greater relative decrease of the vanillin solubility than in the corresponding system without the IL. This was assigned to the negative impact of increased hydrotrope pre-aggregation in the presence of inorganic salts. The results were rationalised using statistical thermodynamics through which hydrotrope aggregation prior to solute addition is shown to be detrimental to the hydrotropic effect, seemingly confirming solute-induced clustering of the hydrotrope to be the predominant mechanism of hydrotropy.