Study of the Thermodynamic Equilibrium of Fragrance Mixtures, Limonene, Linalool and Geraniol, using the Unifac and Cosmo-Sac Models and the Estimation of their Combined Properties in Binary, Ternary and Quaternary Mixtures

Abstract

Perfume is a non-ideal complex mixture of chemicals originating from the extraction of essential oils and these oils are volatile components extracted from plants, some animals, or even synthesized. For this reason, to compose a fragrance, there are countless possibilities to combine one element and another, which makes the process slow and expensive. Therefore, in this study, we will combine three components of the most known and accepted in the cosmetic industry that make up most essential oils, they are Limonene, linalool, and geraniol. The effect of these combinations generates an influence on the diffusive behavior, on the volatility of the mixture and on the odor intensity of its constituents, due to molecular interactions, its physicochemical properties and the presence of liquid and vapor phases. Therefore, some thermodynamic models and calculations involving vapor-liquid balance, EVL, are the most used tools to predict perfume performance and quality. In general, these models start from the activity coefficient, which measures the non-ideality of the mixture, by the modified Raoult's law, which associates this coefficient to the vapor pressure and to the compositions in each phase. However, being of industrial interest, the use of modeling and process simulations capable of optimizing the time and cost of a product, the research seeks to investigate the application of thermodynamic models of the COSMO and UNIFAC type to estimate the VLE of real mixtures of fragrances, through literature review and computational analysis. The use of the COSMO-SAC thermodynamic model will help to obtain the activity coefficient and the sigma profiles of a combination among the components studied, through the JCOSMO computational package. The UNIFAC model and Raoult's Law for ideal gas/solution will contribute to the estimation of the VLE curves of binary mixtures, the diffusive behavior of fragrances and the fugacity and activity coefficients of binary, ternary and quaternary mixtures, through the process simulator DWSIM. The results obtained showed agreement with the expected behavior, according to the literature. Regarding the efficiency in the use of thermodynamic models, which facilitate the VLE studies of different fragrances and the interactive behavior of these components when mixed, in order to reduce the number of experiments and optimize the process. The biggest challenge of the research was to find programs that could facilitate the analysis of VLE curves, such as the complete JCOSMO, which is not available for free access.