Latin American Applied Research 52(4):337-345 (2022) https://doi.org/10.52292/j.laar.2022.884 337 EXPERIMENTAL BEHAVIOR OF CRUDE SOYBEAN OIL IN ALCO- HOLIC SOLVENTS: MISCIBILITY TEMPERATURE AND CHILLING SEPARATION EFFECTIVENESS N.Y. OTERO †‡ , E.R. BAÜMLER †‡ , A.A. CARELLI †‡ and M.E. CARRÍN †‡§ † Departamento de Ingeniería Química, Universidad Nacional del Sur, 8000 Bahía Blanca, Argentina ‡ Planta Piloto de Ingeniería Química - PLAPIQUI (UNS-CONICET), 8000 Bahía Blanca, Argentina § Corresponding author: E-mail: mcarrin@plapiqui.edu.ar Abstract−− Experimental information about the behavior of crude soybean oil with alcohol solvents, useful in the design of oil extraction and separation processes, is provided. The miscibility temperature of crude soybean oil in ethanol, isopropanol and their mixture (M) at different oil/alcohol ratios (OAR), and both the oil equilibrium distribution coefficients (keq) between formed phases and the amount of oil recov- ered (OR) from the chilled miscellas were determined. In the analyzed OAR range, the highest miscibility temperatures were 78, 40 and 55 °C for ethanol, iso- propanol and M, respectively. Generally, OR and keq changed significantly with the solvent, the chilling temperature and the OAR. By using ethanolic miscel- las, a more effective separation was reached, being OR slightly changed with the chilling temperature. The validation of the chilling separation, performed using miscellas obtained from the ethanol extraction of soybean oil, demonstrated that other extracted compounds did not affect the separation yield. Keywords−− Ethanol, isopropanol, phase sep- aration, oil recovery, alcoholic miscella, soybean. I. INTRODUCTION In an oil extraction conventional process from soybean and other oilseeds, hexane is the solvent commonly used because of its low cost and high solubilizing power, pre- senting positive economic aspects and high oil yields. However, as it is a flammable petroleum-based solvent, it poses safety, environmental, and health risks (Rapinel et al., 2020; Russin et al., 2011). Concerns about hexane availability, tighter restrictions on emissions and higher safety requirements have renewed interest in the study of alternative solvents in the scientific sector, anticipating the future requirements of the industry. However, the shift to other solvents from renewable sources or with less environmental impact must be supported by knowledge not only of the new parameters of extraction and the expected oil quality, but also of the modifications required in pre- and post-treatment of the oilseed mate- rial, among other factors. As hexane is still used and pre- ferred by the oil industry, some of this required infor- mation is very scarce in the open literature, with only un- specific and incomplete data obtained in a non-system- atic way. Among alternative solvents, alcohols such as ethanol and isopropanol (IPA) are promising options since they are safer and less toxic than hexane, and they can be pro- duced from renewable resources. Many studies have demonstrated that both alcohols are effective in the ex- traction of soybean oil (Gandhi et al., 2003; Lusas et al., 1997; Sawada et al., 2014; Seth et al., 2007; Toda et al., 2016), obtaining higher oil yield or needing lower extrac- tion temperature when ethanol or IPA are used, respec- tively. IPA is more expensive than ethanol. So, consider- ing the benefit that each one can provide to the extraction process and their cost, solvent mixtures could also be an option to combine their advantages (Singer and Deobald, 1945; Comerlatto et al., 2021). However, there is very scarce and no updated or specific information published on this important subject. As an approach for oil extrac- tion, recent studies tested ethanol-hexane mixtures (Phan et al., 2021) and ethanol-IPA mixtures, where all the ex- tracted material was considered as oil (Comerlatto et al., 2021). Moreover and from an economic analysis, it was indicated that mixtures 1.2:0.8 ethanol:IPA or enriched in ethanol would be preferred when extraction is per- formed at 50 °C, but the optimal condition would depend on the process temperature (Comerlatto et al., 2021). Nevertheless, alcohols present lower selectivity towards triacylglycerols than hexane, with other compounds be- ing extracted together with the oil (Baümler et al., 2016; Citeau et al., 2018; Mabona et al., 2014). This is not nec- essarily a disadvantage, but it must be taken into account to properly characterize the oil yield and the product quality and also to evaluate the required post-treatment. Different studies have indicated that oils and meals ex- tracted using alcohols as solvents have identical or better quality compared to those obtained with hexane (Baüm- ler et al., 2016; Gandhi et al., 2003; Sawada et al., 2014; Seth et al., 2007). One of the disadvantages associated with alcohol sol- vents compared to hexane is the high energy requirement due to the low solubility of oil at low temperatures (T~60 °C, typical extraction temperature using hexane), forcing to operate during extraction at or near their boiling points, and the higher latent heat of vaporization (to be consid- ered when the solvent is recovered by distillation). How- ever, as the oil solubility in IPA and ethanol decreases with temperature, both alcohols could be partially re- moved from the miscella by chilling, obtaining two phases. The formation of these phases would also allow a partial deacidification of the oil (Lusas et al., 1997). This aspect has been studied from a thermodynamic point