Excess molar enthalpies in the binary system of carbon dioxide + ethyl lactate at 298.15 and 303.15 K and 5.0–7.0 MPa

Abstract

This paper presents an experimental determination of the excess molar enthalpies (HE) for the binary system of carbon dioxide (CO2) + ethyl lactate at temperatures of 298.15 and 303.15 K and pressures in the range of 5.0–7.0 MPa. A maximum exothermic value of approximately 7.4 kJ mol−1 was found, similar to the exotherms observed in our previous work for other binary systems such as CO2 + ester or ether. We discussed this exothermic behavior based on the change-of-state contribution, strong CO2-ester interactions, and unusual intra- and intermolecular hydrogen bonding of ethyl lactate. The experimental HE data correlated well with a composition-dependent equation and the Peng–Robinson equation of state with the van der Waals one-fluid mixing rule.