Flash point and excess molar volumes of binary mixtures containing d-limonene and alcohol compounds from propanol to dodecanol

Abstract

D-limonene is a monoterpene naturally found in citrus peels, especially lemons and oranges, and is responsible for their strong odour. D-Limonene has specific properties that enable its use in various industrial segments such as foods, perfumes, beverages, cosmetics, pharmaceuticals, detergents, soaps, insecticides, disinfectants, fine chemicals, as a biodegradable solvent, and so on. Among the ways in which limonene can be used, the mixture of d-limonene with alcohol compounds has a great application potential, since alcoholic extracts of citrus essential oils have high solubility in aqueous solutions, reducing the occurrence of oxidation reactions as well as increasing the aromatic resistance of the mixture. However, studies on the thermodynamic properties of alcohol compounds and terpenes mixtures are still scarce. Thus, in this study, the density (ρ) and excess molar volume data (VmE) of seven binary mixtures of d-limonene with 1-propanol, 1-butanol, 1-pentanol, 1-hexanol, 1-octanol, 1-decanol and 1-dodecanol were determined at 298.15 K and throughout the whole mole fraction range. The flash point (FP) of these same mixtures was also determined from the 0.0 to 1.0 mol fraction range. The FP experimental values were compared to FP values calculated using Liaw’s approach and the activity coefficient models UNIQUAC, NRTL, UNIFAC and Ideal, with an average deviation of (0.55, 0.57, 1.43 and 4.02) K, respectively. The interaction parameters of the models UNIQUAC and NRTL were thus shown to be well adjusted and provide a better description of the FP behaviour than the ideal and UNIFAC models, as expected. The excess molar volumes calculated with use of density determination were all positive, indicating that the molecule interactions in the mixtures are weaker than those in the pure components causing an expansion of excess molar volume (>0). This behaviour was also corroborated by the activity coefficients calculated.