EFFECT OF IONIC SIZES OF HALIDE ANIONS OF POTASSIUM SALTS ON SURFACE AND INTERFACIAL TENSIONS OF BENZENE AND WATER INTERFACES FOR MUTUAL MIXING

Surface tension (γ, mN/m) of potassium halide salts with water and interfacial tension (IFT) (±0.01 mN/m) of benzene interfaces with water are reported at 298.15 K temperature. The 0.1, 0.5 and 1.0 mol kg-1 potassium fluoride (KF), chloride (KCl), bromide (KBr) and potassium iodide (KI) solutions were studied. The KCl, KBr, KF and KI increased the surface tension by 5.2, 4.0, 3.1 and 3.0%, respectively, with salt–water interaction influence by anionic sizes. The surface tension of water from air–water to benzene–water interfaces is decreased by 51% due to the benzene–water mutual interaction with dipolar and π-conjugation. The KI, KF, KCl and KBr salts decrease the IFT by 63, 61, 61 and 56%, respectively, because of larger differences in sizes of the anions and the K+ with individual salt. The KI developed stronger interactions with an induced potential of a large sized I- anion that held the water engaged and integrated the aqueous phase with higher interfacial tension. The dipolar and π-conjugation interaction model is proposed with biphasic systems.