Extraction of Fixed Oils from Grounded Seeds with Near Critical CO2 + Propane Mixtures

PABLO E. HEGEL; GUILLERMO D. B. MABE; MARCELO S. ZABALOY; ESTEBAN A. BRIGNOLE

Rio de Janeiro, Brasil

Congreso; Second Mercosur Congress on Chemical Engineering fourth Mercosur Congress on Process Systems Engineering; 2005

Universidad de Rio de Janeiro

Solvents like propane and carbon dioxide have been studied in previous works at supercritical and sub-critical conditions and also as high-pressure liquid solvents for the extraction of lipids and oils. Propane is completely miscible with fixed oils at room temperature but has liquid-liquid phase equilibrium with vegetable oils at temperatures between the lower critical end point (LCEP) and the upper critical end point UCEP) - around 340 and 370 K for typical vegetable fixed oils. In this temperature range the Propane solvent power for triglycerides is drastically reduced unless much higher pressures are used to recover the single phase region. The use of Propane + Carbon Dioxide mixtures can offer special properties regarding solvent power, selectivity and safety. In the present work the extraction performance of a bed of grounded seeds using near critical mixtures of Propane + Carbon Dioxide is studied. Previous experimental work on phase equilibria of fixed oils + propane + Carbon Dioxide have shown the possibility of obtaining complete miscibility in the near critical (liquid) state of these ternary systems operating at room temperature. The CO2 concentration effect on the emergence of the liquid-liquid equilibrium phenomena in ternary mixtures with propane and oil, and the effect of operating under these conditions on the extraction rate is studied. The extraction studies were carried out on hiprose seeds, and sunflower oils seeds in a high pressure (five liter) extractor where the seeds are extracted under percolation conditions in the temperature range from 25 to 50ºC and at pressures in the range of 15 to 60 bar.