Use of liquid carbon dioxide to remove hexane from soybean oil

Abstract Liquid carbon dioxide (L‐CO2) was investigated as a means to separate hexane from the mixture of soybean oil (SBO) and hexane resulting from the hexane extraction of soybeans. Using a fractionation tower, 5 vol of CO2 (i.e., 100, 200, 300, 500, and 1000 L expanded gas) were passed through 50 mL of two concentrations of n‐hexane (i.e., 10 and 25% w/w) in SBO. After passing through the hexane/SBO mixture, the expanded CO2 was passed through a chilled collection flask to capture extracted hexane and SBO. The raffinate SBO was removed from the column and analyzed for residual hexane using International Organization for Standardization Method 9832:2002. Residual hexane decreased as the amount of L‐CO2 used increased and was less than 20 ppm after 200 L of CO2. The amount of SBO extracted increased with the volume of CO2 used. Significantly more SBO and hexane were collected from the 25% sample than the 10% sample. During the extraction of the mixture, the CO2 selectively carried over TG with lower M.W. This research demonstrates the ability to use L‐CO2 to remove haxane from mixtures of hexane and SBO at both low pressures and temperatures.