ORIGINAL ARTICLE Separation of Sunflower Oil from Hexane by Use of Composite Polymeric Membranes C. Pagliero • N. A. Ochoa • P. Martino • J. Marchese Received: 28 September 2010 / Revised: 14 April 2011 / Accepted: 18 April 2011 / Published online: 19 May 2011 Ó AOCS 2011 Abstract Vegetable oil extraction, as performed today by the oilseed-crushing industry, usually involves solvent extraction with commercial hexane. After this step, the vegetable oil–hexane mixture (miscella) must be treated to separate its components by distillation. If solvent-resistant membranes with good permeation properties can be obtained, membrane separation may replace, or be used in combination with, conventional evaporation. Two tailor- made flat composite membranes, poly(vinylidene fluoride) (PVDF–Si and PVDF–CA) and a commercially available composite membrane (MPF-50), were used to separate a crude sunflower oil–hexane mixture. The effects of tem- perature, cross-flow velocity (v), transmembrane pressure (Dp), and feed oil concentration (C f ) on membrane selec- tivity and permeation flux were determined. The PVDF–Si membrane achieved the best results, being stable in com- mercial hexane and having promising permselectivity properties for separation of vegetable oil–hexane miscella. Improved separation performance was obtained at C f = 25%, Dp = 7.8 bar, T = 30 °C, and v = 0.8 m s -1 ; a limiting permeate flux of 12 Lm -2 h -1 and 46.2% oil retention were achieved. Low membrane fouling was observed under all the experimental conditions studied. Keywords Vegetable oil  Solvent recovery  Membrane separation  Nanofiltration Introduction The extraction of vegetable oil from oilseeds involves sol- vent extraction with an organic solvent, normally com- mercial hexane. As a result of the extraction process, a mixture (miscella) of oil and hexane (usually 25–35% w/w of oil) is obtained. The miscella undergoes a complex process of distillation and condensation to recover the sol- vent, which is re-used. Solvent is removed from the mis- cella by the double effect evaporation and steam stripping [1]. The equipment used in the first stage, called an econ- omizer, is designed to remove most of the solvent and concentrate the miscella as much as possible (70–90% oil). The concentrated miscella is then pumped to the second- stage evaporator (under partial vacuum), where the oil concentration is increased to [ 99% ( \ 1% hexane). Solvent recovery is of great importance because it affects the global economy of the process, industrial safety, and environ- mental protection. During the last three decades membrane technology has been accepted in various food processing applications in which its use leads to increased product yield and quality, and with substantial energy savings. It has been estimated that in the USA about two trillion of Btu per year could be saved by using a hybrid membrane system to recover solvents in the extraction of crude oils [2]. Fundamental aspects of membrane separation processes related to degumming, dewaxing, deacidification, solvent recovery, etc., have been recently reviewed [3]. Use of membranes in the vegetable oil extraction industry is cur- rently limited compared with other food industries. Several researchers [4, 5] have reported on the permeation of dif- ferent families of organic solvents using nanofiltration (NF) membranes. Much work has been reported on the use of membranes in the degumming process and in the separation of undesirable compounds present in vegetable oils C. Pagliero  P. Martino Facultad de Ingenierı ´a, UNRC, Ruta No 36, Km 601, 5800 Rı ´o Cuarto, Argentina N. A. Ochoa  J. Marchese (&) Universidad Nacional de San Luis, INFAP, Chacabuco 915, 5700 San Luis, Argentina e-mail: marchese@unsl.edu.ar 123 J Am Oil Chem Soc (2011) 88:1813–1819 DOI 10.1007/s11746-011-1839-3