Recent Projects
Oligomerization of Lactic Acid
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Lactic acid is currently under major development as a feedstock from bioprocessing. The properties are important for process modeling. Lactic acid forms oligomers as water is removed from the solution because the hydroxyl on one molecule forms an ester with the carboxylic acid on another molecule. The reaction produces a water molecule, that can be subsequently evaporated. Thus the superficial content can to to 125% free acid when the water for hydrolysis is considered. Lactic acid forms a polyester as the water is removed. Therefore it is not possible to isolate pure lactic acid in the free acid form. The properties of free lactic acid must be estimated. Solutions of lactic acid consist of oligomers. Shown on the left are some literature data for oligomer concentrations. The solid lines show a model developed at MSU that successfully models the oligomerization behavior. We are interested in the processing of lactic acid solutions and the impact and participation of oligomers in reactions and phase equilibria. The oligomer concentrations have been determined at MSU by HPLC. The data from the literature are from preparatory chromatography. This project is in collaboration with DJ Miller, Department of Chemical Engineering and Materials Science at MSU. |
Isolation of Sulfolipid
TLC plate showing isolation of the sulfolipid, SQDG. |
In this project, we have developed a procedure using non-chlorinated solvents to isolate and purify sulfolipid from natural extracts. Sulfolipid (SQDG) is a functional glycolipid that has been shown to have activity against the AIDS virus and is antibacterial. The TLC plate to the left shows an overview of the feedstock and separation. SQDG is the desired compound. All lanes have the same quantity of sample. Lane A - extract obtained by the published method using chlorinated solvents. Lane B - extract obtained in this work prior to fractionation. Lane C - After separation from most phospholipids. Lane G - Final purified product. Lane H - a by product stream. MGDG = monogalactosyldiacylglycerol; DGDG = digalactosyldiacylglycerol; SQDG = sulfoquinovosyldiacylglycerol; PG = phosphatidylglycerol; PI = phosphatidylinositol; PE = Phosphatidylethanolamine; PC = phosphatidylcholine. This project is in collaboration with C. Benning, Department of Biochemistry and Molecular Biology, Michigan State University. |
Adsorption from Supercritical Fluids
Supercritical fluids may be valuable solvents for regenerating valuable species from adsorbents instead of conventional solvents. In particular, they may be valuable solvents for recovery of food products or flavors that are concentrated by adsorption. In this work, we have measured breakthrough and regeneration curves for benzyl alcohol and benzaldehyde from CO2. Manuscripts are in preparation.
Recovery of Natural Cherry Flavor using Adsorption with CO2 Regeneration
This project considered recovery of natural cherry flavor (benzaldehyde) from cherry pit hydrolyzate and subsequent regeneration using CO2. The project was successful technically, but the yield from natural cherry pits was too low to yield sufficient product. We are interested in other compounds that may be amenable to this type of processing.
Modeling of Adsorption using Equations of State
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Equations of state provide a powerful engineering method to calculate adsorption from low pressure to supercritical conditions. Since equations of state can model both vapor and liquid states, the equation of state is solved near the solid surface. This work is novel because the geometry of the adsorbent (flat wall, slit, etc.) is incorporated into the equation of state. The adsorption is found by integrating the resulting density profile within the pores. When the attractive forces of the adsorbent are strong, the pore is filled with liquid. When the adsorption forces are nonexistent, there is a fluid depletion near the walls. This work has been published for pure fluids. Publications are underway for mixtures. The figure at left is literature data for the component adsorption of benzene from a benzene + CO2 mixture above the critical point of CO2. Only the benzene adsorption is reported experimentally. The model also calculates the CO2 adsorption (not shown). Therefore the model is capable of modeling regeneration of adsorbents and also behavior in porous membranes. |
Separation of Lipids by Functionality using Liquid-Liquid Extraction and Adsorption
As genetic engineering results in functional lipids for specialty applications, there will be increasing need for separations to purify these functional lipids. In this work, we measure the distribution of castor and soy oil between hexane and ethanol. We have also considered fractionation by adsorption.