Journal of Chemical Thermodynamics, Vol.55, 151-158, 2012
On the phase behaviour of polyethoxylated sorbitan (Tween) surfactants in the presence of potassium inorganic salts
The salting out potential of potassium-based inorganic salts was assessed in aqueous solutions of two non-ionic surfactants from the Tween family. New solubility data of the systems {surfactant (Tween 20/Tween 80) + inorganic salt (K3PO4/K2CO3/K2HPO4/K2S2O3/K2SO3) + H2O} were experimentally ascertained at T = 298.15 K and these data were correlated by means of several three and four parameters empirical equations. Tie-line data were determined for the aqueous ternary systems and Ohtmer-Tobias and Bancroft equations have been proposed to correlate these data. The phase segregation effect of the proposed salts was investigated and compared with the sequence indicated by the Hofmeister series and the molar Gibbs energy of hydration (Delta(hyd)G) data. (C) 2012 Elsevier Ltd. All rights reserved.
Keywords:Aqueous Biphasic Systems;Tween 20;Tween 80;Potassium salts;Othmer-Tobias and Bancroft equations