Deacidification of soybean oil using supercritical fluid and membrane technology

Abstract

Membrane processing has been used for oil purification, but low flux and membrane instability are major impediments. A technique that combines membrane processing and supercritical CO 2 was investigated. A specialized, high-pressure, dead-end membrane cell was designed, fabricated, and connected to two ISCO (Lincoln, NE) supercritical fluid extraction (SFE) systems. The cell has a base with a grooved bottom for permeate removal, plus a porous metal disc for membrane support; a cell body with threaded connections; and a cap with an inlet assembly. One SFE pump provided the appropriate pressure on the feed stream, the second maintained pressure on the permeate at a slightly lower pressure. The sample consisted of 50% TAG and 50% FFA. For example, for separations at 45°C and a transmembrane pressure of 7 atm, the β (selectivity factor) values (TAG, FFA) for the SE and BW membranes were 0.56, 3.63 and 0.60, 2.63, respectively, whereas the β values (TAG, FFA) for the DK and NF90 membranes were 0.58, 1.37 and 0.70, 1.28, respectively.Paper no. J11076 in JAOCS 82, 803-808 (November 2005).

Deacidification of Soybean Oil Using Membrane Processing and Subcritical Carbon Dioxide

“…1. The system has been described in detail previously [4,5] and the same equipment set-up was used with slight modifications, e.g., a co-solvent pump was not used in this experiment. A supercritical extractor SFX-210 and a 100DX syringe pump with 100 mL capacity (ISCO Inc., Lincoln, NE) and with temperature control and monitoring systems were used for the solubility and membrane studies.…”

“…Fats and oils could be selectively extracted using pressurized fluids, but the capital costs are very high, which makes this process unattractive economically. Research done by Artz et al [4,5] on the use of supercritical carbon dioxide in combination with membrane technology indicated that the technology shows promise for the deacidification of crude vegetable oil. However, the processing conditions required for supercritical fluids greatly exceed those normally used for membrane processing, which presents some difficult technical challenges.…”

Sub- and supercritical fluid technology applied to food waste processing

“…The cost of recompression of CO 2 to liquid or supercritical state is high. In this sense, coupling SFE to membrane separation allows keeping CO 2 in the process conditions, resulting in a significant energetic economy in terms of recompression costs [118,122,123]. Another advantage is the possibility to operate with high permeate flux, due to the low viscosity of supercritical CO 2 (ten times lower than water, with diffusivity 10 to 100 times higher [116,118].…”

“…Both alternatives lead to additional costs, directly related to the need of security equipment, more energy expenses, and other separation procedures needed for environmentally reasons, and also to degradation of the product. In this sense, a new crossflow filtration process was proposed, taking advantage of the low viscosity and superficial tension of supercritical CO 2 [123,126,127]. Indeed, this process increases the quality of the product and is environment friendly.…”

Simultaneous improvement in solvent permeability and deacidification of soybean oil by nanofiltration

“…Another potential solution is the use of hybrid processes, i.e. the supercritical CO 2 process combined with membrane technology (Koseoglu 1991;Artz et al 2005;Lai et al 2008).…”