ARS | Publication request: Counter-current liquid carbon dioxide purification of a model reaction mixture

Submitted to: Journal of Supercritical Fluids
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: July 26, 2007
Publication Date: January 15, 2008
Citation: Eller, F.J., Taylor, S.L., Compton, D.L., Laszlo, J.A., Palmquist, D.E. 2008. Counter-current liquid carbon dioxide purification of a model reaction mixture. Journal of Supercritical Fluids. 43(3):510-514.

Interpretive Summary: Soybean oil (SBO) can be enzymatically combined with ethyl ferulate (EF) to form a natural sunscreen called SoyScreen(TM). After the reaction is finished, leftover EF and by-product fatty acid ethyl esters (FAEEs) must be removed from the mixture before the product can be used as a sunscreen or as a natural antioxidant. The use of high temperature and vacuum to distill off the EF and FAEEs did not completely remove them and also tended to give the product an undesirable dark color. Researchers at the National Center for Agricultural Utilization Research, Peoria, Illinois, studied the use of liquid carbon dioxide (L-CO2) to purify the SoyScreen(TM) reaction mixture. This new technology provides an effective tool for purification of this natural sunscreen made from SBO using carbon dioxide, which is inexpensive, non-toxic, non-flammable, and environmentally friendly.

Technical Abstract: The enzymatic reaction of soybean oil (SBO) triacylglycerides (TAGs) with ethyl ferulate (EF) produces the product feruloylated acylglycerols, called SoyScreen(TM) as well as by-product fatty acid ethyl esters (FAEEs). The unreacted EF and FAEEs must be removed from the mixture before the feruloylated acylglycerols can be used as natural sunscreens and/or antioxidants. This research investigated the use of the continuous L-CO2 counter-current fractionation method to purify the reaction mixture from the enzymatic synthesis of SoyScreen(TM). The effect of column length, solvent:feed (S:F) ratio and total flow were examined. At a given S:F ratio, the purity of the raffinate increased with column length. Raffinate purity increased with S:F ratio as well and, using a 120 cm long column and a S:F ratio of ca. 11.9, the raffinate was essentially free of EF and FAEEs. When the total flow was doubled while the S:F was held constant, there was no loss of purity of the raffinate.