REMEDIATION TECHNOLOGY--OXIDATION OF HAZARDOUS CHEMICALS IN SUPERCRITICAL WATER

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We are proposing to obtain fundamental kinetic data on the destruction of hazardous model chemical compounds by oxidation in supercritical water. This work has already begun with identification of model components. Criteria important to the selection process include frequency of occurrence in ground water contamination incidents, degree of toxicity, and chemical structure and bonding characteristics (Are the model compounds good surrogates for more complex chemicals?) Wastes containing mixed solvents and inorganic salts are particularly important in pump-and- treat type remediation procedures. For example, the dominant chemicals found in the groundwater of the Aberjona Basin studies include trichloroethylene, benzene, and toluene with salts predominately of arsenic and chromium. Multiphase feeds involving organics and salts dissolved in water and absorbed to soil particles will also be characterized to select surrogates. these PIC compounds will be characterized by the core toxicology laboratory to determine mutagenicity and by the core analytical laboratory components to identify and separate the specific compounds involved. Our specific approach involves a coupled experimental and theoretical modeling effort to determine global kinetic expressions and to interpret mechanistic pathways. The effects of operating at off-design conditions on product distribution and destruction efficiency will be studied over a wide range of temperature, pressure and reactor residence times. Furthermore, the thermodynamic stability of reaction intermediates will also be studied in terms of their influence on reactor performance. The new kinetic data we obtain on the oxidation of model compounds in supercritical water will permit the evaluation of this process as a technology for remediation. For the first time, quantitative kinetic measurements will be conducted on mixed feeds under isothermal conditions and the thermodynamic stabilities of partial oxidation products will be examined in light of their potential influence on reactor performance. Solids (oxides and salts) and complex organic compounds have shown increased stability at supercritical temperatures by their effect on oxidation rates and final product distribution is not known.