This project will develop a portable supercriticalfluid extraction system that can directly extract heavy metalsfrom wastewater. A distinct advantage of this system is that itcan remove these contaminants directly from wastewater residentat government and industrial facilities. The extraction processis accomplished by introducing a fluorinated chelating agent(hexafluoro acetylacetonate, or bistrifluoroethylenedithiocarbamate) to the contaminated sample, thereby complexingthe metal and allowing the formed neutral metal chelate to beextracted in situ with supercritical carbon dioxide (CO2) ormodified supercritical CO2. Fluorinated ligands possess highervolatility than their neutral hydrocarbon analogs and theresulting complexes exhibit a higher solubility in supercriticalCO2. A modifier such as methanol or acetonitrile will be added tothe supercritical CO2 to increase the solvating power ofsupercritical CO2. Detection of the metal chelates isaccomplished using gas or liquid chromatography and atomicemission or atomic absorption spectrometry. Different pressuresand temperatures are applied to optimize the extractionefficiency. This method is very cost effective, since there is nosolvent to dispose of, and it is very effcient because of thephysical and chemical properties of supercritical fluids. Anticipated Results /Potential Comm.ercial Applications as described by the awardee: The supercritical fluid extraction(SFE) market segment is expected to grow very rapidly for thenext five years, and it is now poised to enter its most rapidstage of development because of the adoption of hydrocarbon basedextraction. However, to grow rapidly, runs utilizing SFE must becarried out on a larger scale, while becoming less expensive andmore automated. It is expected the product of this research willbe used by all the automotive, aerospace, and electronicindustries, as well as those dealing in wastewater. Thistechnique allows 21 substantial savings in both materials costs(through recycling) and the cost of sludge disposal in hazardouswaste landfills.
