Sodium salt effect on aqueous solutions containing Tween 20 and Triton X-102

The effect of six different high charge density sodium inorganic salts, such as Na2CO3, Na2SO4, Na2S2O3, Na2SO3, Na2HPO4 and NaCH3COO, in aqueous solutions of two anionic surfactants Tween 20 and Triton X-102 was investigated at T = 298.15 K and atmospheric pressure. The results were qualitatively analyzed in the light of the Hofmeister series. Also, a quantitative thermodynamic analysis in terms of molar Gibbs free energy of hydration (ΔhydG) was carried out. The Merchuck equation was used to correlate the solubility curves and the tie line data were modelled by applying the Othmer–Tobias and Bancroft equations.

► Several sodium salts act as phase promoters in aqueous solutions of two surfactants.
► Merchuck, Othmer–Tobias and Bancroft equations were used for correlating the systems.
► ΔhydG and Hofmeister series were employed to analyze the different salting out effects.