Volumetric and conductometric studies on the interactions of dipeptides with potassium perfluoroalkanesulfonate in aqueous solution at different temperatures

Density and conductivity data for potassium perfluoroalkanesulfonate ((potassium perfluorobutanesulfonate (PFBS) and potassium perfluorooctanesulfonate (PFOS)) + dipeptide + water) systems were determined at different temperatures. The standard partial molar volume (V2,ϕo), standard partial molar volume of transfer for dipeptide from water to aqueous potassium perfluoroalkanesulfonate solutions (ΔtVo), hydration number (NH), partial molar expansibility (Eϕo) and Hepler's constant for the dipeptides have been calculated from density data. Electrical conductivity was used to estimate the limiting molar conductivity (Λo), Walden product (Λoη) and energy of activation of the transfer process (Ea) of potassium perfluoroalkanesulfonate in aqueous dipeptide solutions. Effects of temperature and the hydrocarbon chain length of the dipeptides on the volumetric and conductometric properties were examined. The results have been interpreted in terms of solute-solvent interactions and structural changes in the mixed solutions.