Ultrasonic velocity, excess adiabatic compressibility, apparent molar volume, and apparent molar compressibility properties of binary liquid mixtures containing 2-butoxyethanol

Abstract

Ultrasonic velocity and density data of binary systems of water–2-butoxyethanol (BE), 2-butoxyethanol-benzene, and 2-butoxyethanol–decane are reported for temperatures of 25, 40, and 55 °C. Adiabatic compressibility coefficients, apparent molar volumes, and apparent molar compressibilities were calculated from these data. Excess adiabatic compressibility properties were evaluated using volume fraction weighting of the individual component properties to estimate ideal mixture behavior. These results are compared with the data obtained based on the use of mole fraction weighting of the individual component properties for the ideal behavior value. A sharp ultrasonic velocity maximum and compressibility minimum is observed at low BE concentration in mixtures of water–BE at all temperatures. These maxima in ultrasonic velocity and minima in adiabatic compressibility are attributed to the formation of "clathrate-like" structures of water and alcohol. A shift of the velocity maximum towards lower concentrations of BE was observed with increase of temperature. A minimum in the ultrasonic velocity and a maximum in adiabatic compressibility coefficient values are observed in systems of BE–benzene and BE–decane. These results are discussed in terms of the breakdown of associated alcohol structures and the interstitial location of hydrocarbon molecules in alcohol aggregates.