On the phase behaviour of polyethoxylated sorbitan (Tween) surfactants in the presence of potassium inorganic salts

► The feasibility of Tween family to form phase segregation is demonstrated. ► Different potassium-based salts are efficient phase promoters in Tween surfactants. ► Hofmeister effects evidenced by the different molar Gibbs free energy of hydration. ► Othmer-Tobías and Bancroft equations suitably represent the experimental TL data.