The fluid-phase equilibria for mixtures of water with biochemical compounds of low volatility, such as sterols and fatty acids, at elevated temperatures and pressures are obtained. An equilibrium flow apparatus which incorporates a view cell with sapphire windows will be used to measure liquid-liquid equilibrium compositions and mixture critical curves. Preliminary results for the oleic acid-water system indicate that oleic acid and water are completely miscible at approximately 310 Degrees Celsius and 125 bar, and thermal decomposition and polymerization reactions at these conditions are minimal. The use of water to separate biocompounds or other compounds of low volatility has not been proposed and no solubility measurements for such compounds with water at elevated temperatures and pressures are known. The recovery of biochemical compounds from naturally occurring oils is of interest to the health care, biotechnology, and specialty chemical industries. The long term purpose of this work is to determine the feasibility of a high-pressure extraction process which would use liquid water at elevated temperatures as a solvent for separating mixtures of biocompounds which naturally occur in resins and oils. If successful, this process would 1) suppress the undesirable sterol-acid reaction which results in product losses, 2) increase the purity of the existing acid products, and 3) allow one to recover beta- sitosterol as a new, high-value product. A successful process would result in a significant new supply of biochemical compounds with many potential uses and would also give the U.S. tall oil industry the ability to handle a diverse source of trees for their raw materials.
