Excess enthalpy and excess volume for binary systems of two ionic liquids + water

In this work we report the experimental measurements of excess molar enthalpy and excess molar volume, at 298.15 K and atmospheric pressure, on ethylammonium nitrate (EAN) and propylammonium nitrate (PAN) + water mixtures. Positive enthalpies were found for the two systems (maximum, at x 1 around 0.37 correspond to about 700 and 900 J mol −1 for EAN and PAN respectively). As the hydrophobic/hydrophilic ratio increases, along with the length of the alkyl chain in the ionic liquids, ILs, the specific interactions IL-water become less important. The excess molar volumes, V E , are negative over the entire composition range for the two binary mixtures. They have similar values but curves exhibit a different asymmetric shape and around equimolar composition they intersect each other. This behaviour: positive H E and negative V E , is not very common.