SOLUBILITY AND PHASES SEPARATION STUDIES IN CRUDE SOYBEAN OIL-ALCOHOL MIXTURES

OTERO, NOELY; BAUMLER, E.R.; CARELLI, A.A.; CARRÍN, MARIA ELENA

Rosario, Argentina

Congreso; World Congress on Oils & Fats; 2015

ASAGA

In order to evaluate the feasibility of using other solvents safer than hexane to extract soybean oil, it is important to know firstly the solutions behavior related to miscibility at extraction conditions and phases separation after that. So, the aim of this work was to determine the behavior of crude soybean oil in absolute alcohols (ethanol, isopropanol and a mixture of them) at different oil/alcohol ratios (20:80, 40:60, 60:40 v/v) to find the operative conditions not only during oil extraction but also to separate the oil from the alcohol. The analyzed variables were: a) whole oil miscibility temperature in the different solvents to determine the lower extraction temperature; b) oil concentration in oil-rich and alcohol-rich phases obtained after chilling oil-alcohol solutions at two final temperatures (20ºC and 6ºC), in order to evaluate the effectiveness of chilling-separation. The advantage of partially replacing the distillation step by phases separation is that a small portion of the total alcohol in the system would require vaporization so it should result in energy savings. The miscibility temperatures of miscellas composed of crude soybean oil and alcohols (40:60 v/v) were observed to be 75ºC, 30ºC and 48ºC for ethanol, isopropanol and the mixture 1:1 (v/v) ethanol/isopropanol, respectively. The results obtained in the study of chilling-separation indicate an increase in oil concentration of the oil-rich phase when the miscellas were cooled at 6ºC, compared to those obtained at 20ºC; but in the ethanol case, only a little additional separation occurred in chilling process below 20ºC. In general, oil concentrations in the oil-rich phase were appreciably higher for ethanol miscellas (82-90%) and lower for isopropanol miscellas (67-80%). Moreover, it was found that equilibrium ratios changed not only by temperature and type of alcohol, but also by initial miscella concentration, showing a nonlinear behavior within phases concentrations in the analyzed range.