Deacidification of Amazonian Pracaxi (Pentaclethra macroloba) and Patawa (Oenocarpus bataua) oils: experimental and modeling of liquid–liquid extraction using alcoholic solvents

Abstract

This paper presents a study about the deacidification of typical Amazonian oils, namely, patawa and pracaxi oils. The liquid–liquid extractions were carried out using three alcoholic solvents: anhydrous ethanol, azeotropic ethanol, and azeotropic isopropanol at 298.15 K and atmospheric pressure. Liquid–liquid equilibrium data for the oils + oleic acid + solvents systems were determined. The azeotropic ethanol was found to be the best extractant for removing free fatty acids (FFAs) since its use provided the highest selectivity values (from 62.98 to more 1.53 × 103), reasonable distribution coefficients (from 1.06 to 1.47), and reduced loss of neutral oil (oil concentrations lower than 1.49 wt% in the alcoholic phases). Moreover, the obtained experimental data were correlated using the nonrandom two-liquid (NRTL) and universal quasi chemical (UNIQUAC) activity coefficient models. The deviations between calculated and experimental values ranged from 0.39 to 1.22 and from 0.28 to 1.10 for the various studied systems using the UNIQUAC and the NRTL models, respectively. Such results indicate the positive perspective of using the liquid–liquid extraction technique for patawa and pracaxi oils refining and the feasibility of using ethanol as an FFA extractant.