Prediction of Liquid Molar Volume and Heat of Vaporization of Fatty Acids Using an Equation of State

Abstract

The liquid molar volume (V) and the heat of vaporization (ΔHVAP) of four fatty acids (n-Heptanoic acid, Hexadecanoic acid, n-Hexanoic acid and n- Dodecanoic acid) have been estimated. This paper aims to calculate the liquid molar volume and the heat of vaporization of four fatty acids under the critical point using two traditional equations of state: Peng-Robinson (PR) [21] and Soave-Redlich-Kwong. The area rules method applicable to obtaining the saturation pressure of the compounds has been used. The properties of the acids investigated in this work have been compared with those provided by literature. For molar volumes, the equations of state have given improved predictions when compared to traditional equations such as Rackett equation and so on. According to the vapor enthalpy calculations, no reference value was required. In general, the Clausius-Clapeyron equation provides a better estimation of the vaporization enthalpy of fatty acids when Soave-Redlich-Kwong (SRK) equation was used. The heat of vaporization for fatty acids can be calculated with good reliability in comparison with the Watson equation if suitable equation of state is used. Accurate results for heat of vaporization can be reached in comparison with the Watson equation if the reliable equation of state is used.