Topological transformation of phase diagrams water – ethoxylated nonylphenols – sodium chloride systems

Abstract

In this work phase equilibria in water – ethoxylated nonylphenol (Neonol) – sodium chloride systems was investigated, and temperature ranges of two-phase liquid and monotectic equilibrium region existence were established. These regions exist at temperature of more than 23 ºC in system with Neonol AF-9-12 and more than 42 ºC in system with Neonol AF-9-25. A feature of water – Neonol AF-9-12 – sodium chloride system is the salting-out of double water – Neonol AF-9-12 subsystem at the temperature of more than 84 ºC. A scheme of phase diagrams of topological transformation of water – ethoxylated surfactant – inorganic salt systems for cases, when salt has only salting-out effect and water – surfactant subsystem is characterized by a lower critical solubility temperature (Neonol AF-9-12) or homogeneous throughout liquid state interval was developed. The correspondence of developed schemes to generalized scheme for the salt — binary solvent systems was shown. The data obtained allow evaluating surfactant ethoxylation degree effect to sodium chloride salting-out ability. It was found that ethoxylation degree increase is accompanied by increase in surfactant micelles hydration, which leads to decrease in the salting-out ability of sodium chloride. The obtained data can be used to optimize the temperature and concentration extraction parameters.