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In this study, liquid–liquid equilibriums are reported for different ternary systems of aqueous solutions with decane as oil and mono-ethylene glycol butyl ether (C 4 E 1 ) as surfactant. The appearing Winsor phases and their evolution are shown by drawing temperature versus surfactant weight fraction for a given ratio of aqueous solution to oil. The obtained diagrams have the well-known fishlike shape. Four parameters are used to discuss the influence of the additives: the perpendicular and horizontal asymptotes to the realms-of-existence of the Winsor III phase. The two horizontal asymptotes, i.e., the LCST (lower critical solution temperature) and UCST (upper critical solution temperature) show no significant changes upon adding chloride salts, except for the triethylphenylammonium cation as counter-ion. By contrast, significant changes of the values of these two parameters are found when the nature of the anion of sodium salts changes. The two perpendicular parameters γ 0 (minimum concentration of surfactant needed to form a Winsor III) and γ ˜ (minimum surfactant concentration needed to reach the Winsor IV phase from a Winsor III one) are only little affected by the nature of the additive. Two other parameters in relation with Winsor III area are also studied: δ reflects the vertical extent of the realms-of-existence of Winsor III versus temperature ( δ = UCST − LCST), while ξ = γ ˜ − γ 0 reflects its horizontal extension. The value of δ is affected by the nature of the anion of sodium salts and strongly increases in presence of Na 2 SO 4 , but also with sucrose as additive. The effect of additives has in general a more pronounced influence on the values of the LCST and UCST than on ξ . The results are discussed in terms of Hofmeister effects, of salting-in and salting-out and of the resulting depletion and adsorption on the interfacial film of the Winsor III middle microemulsion. [ABSTRACT FROM AUTHOR]

In this study, liquid–liquid equilibrium measurements were performed for different ternary, water (or brine)/decane or dodecane/mono-propylene glycol ether (C 3 P 1 ) or di-propylene glycol ether (C 3 P 2 ) systems in order to build the so-called fish phase diagrams (temperature as a function of surfactant for a given polar-apolar solvent mixture) and to compare them to the well-known water (or brine)/decane or dodecane/ethylene glycol mono-butyl ether (C 4 E 1 ) phase diagrams. The study is motivated by the lower toxicity of the C x P y compared to the corresponding C x E y . Toxicity is of particular importance for any use of such molecules in the environment. Like in the presence of C 4 E 1 , the formation of Winsor type I → III → II phase transitions with increasing temperature was observed for the C x P y systems. The LCST (Lower Critical Solution Temperature) and UCST (Upper Critical Solution Temperature) of the newly studied systems were determined. The values of the γ 0 parameter (in mole fraction), the minimum value of surfactant needed to form Winsor III, increased in comparison to the C 4 E 1 systems. The value of γ ˜ (in mole fraction), minimum value of surfactant needed to reach Winsor IV from Winsor III, was comparable using C 4 E 1 and C 3 P 1 , and lower in the presence of C 3 P 2 . The substitution of decane by dodecane led to a stronger water affinity of C 4 E 1 and C 3 P 2 as greater values of the LCST and UCST have been observed in the presence of dodecane. By contrast, a lower hydration of C 4 E 1 and C 3 P 1 was found when increasing the NaCl content in brine. It can be concluded that less toxic C 3 P 1 and C 3 P 2 can be envisaged as a substitute of the contested C 4 E 1 to formulate microemulsions and particularly Winsor III systems. [ABSTRACT FROM AUTHOR]

Abstract: In this work, the phase behavior of mixed solvent electrolyte systems containing 1-butanol+water+ammonium chloride at temperatures of 298.15, 308.15 and 318.15K and at atmospheric pressure have been studied experimentally and theoretically. For the studied systems, liquid–liquid equilibrium has been observed throughout the studied temperature range. Ammonium chloride shows a salting out effect in the two phase region, while temperature has a minor effect on the liquid–liquid equilibria in the studied temperature range. The measured experimental data have been modeled using a modified version of the extended UNIQUAC model. The model has been found to give a satisfactory description of LLE data obtained in this work, with an average absolute deviation of less than 1.5% in calculated mass fractions compared to experimental data. [Copyright &y& Elsevier]

Abstract: In this work liquid–liquid equilibria (LLE) in the system containing 1-butanol–water–sodium nitrate at temperatures of 25 and 35°C has been investigated experimentally and theoretically. The extended UNIQUAC model has previously been used for correlation of liquid–liquid equilibrium in aqueous salt systems containing alcohols. In that model the excess Gibbs energy consists of two terms, the original UNIQUAC term and Debye–Hückel term which considers the alcohol as a non-electrolyte solute. In this work, a modified extended UNIQUAC model is used by taking into account mixed solvent theories. The model consists of three terms, the original UNIQUAC term, a Pitzer–Debye–Hückel term and a Born term. The model has been found to give a satisfactory description of LLE data obtained in this work, with an average absolute deviation of less than 0.5 in calculated mass percent compared to experimental data. [ABSTRACT FROM AUTHOR]