PHENOL ESTIMATION USING FLORY-HUGGINS PARAMETERS AND CLOUD POINT OF POLIETHOXYLATE SURFACTANTS

This work examines the thermodynamics of phenol extraction by cloud point varying the ethoxylation degrees of nonylphenolpoliethoxylate surfactants (NPEOn) (9.5, 10, 11 and 12). The Flory-Huggins model was applied to estimate enthalpy (ΔHmix) and entropy (ΔSmix) parameters of the mixture, as well as the aggregate number (N). Results show that ΔHmix and ΔSmix values have a direct relationship with the ethoxylation degree of the surfactant used. Differently, aggregate number (N) values have an inverse relationship with the ethoxylation degree. The fitting to the Flory-Huggins model presented a standard deviation (SD) that ranged from 0.161 to 4.037 for each surfactant studied. It was observed that the increase of the phenol concentration in the surfactant + water system resulted in a decrease in the cloud point of the studied surfactants. These results contribute significantly to the application of this type of surfactant in phenol extraction processes.