Surface thermodynamics of binary mixtures of aliphatic alcohols in heavy water

The surface tension, sigma, of binary mixtures of heavy water and homologous series of aliphatic alcohols (methanol, ethanol, and 1-propanol) were measured over the entire concentration range at various temperatures. The surface tension of these aqueous binary mixtures shows more concentration dependence on the heavy water-rich side. Addition of a small amount of alcohol reduces the surface tension of heavy water drastically. The surface thermodynamic functions such as surface entropy and surface enthalpy have been derived from the temperature dependence of the surface tension values. The magnitude of these thermodynamically quantities is discussed in terms of the nature and type of intermolecular interactions in binary mixtures. The presence of a maximum point in the surface entropy diagram in all systems is explained by the formation of clathrate-like solvates at the surface of these systems. The surface tension of the above mentioned binary systems were correlated with empirical and thermodynamic based models. The Myers-Scott (MS) model with three adjustable parameters gives good results when values of Delta sigma are large. (C) 2012 Elsevier Ltd. All rights reserved.