Project Summary (1995-2000)

The overall goal of this project is to provide new, quantitative understanding of the destruction of hazardous chemicals by wet oxidation and hydrolysis in supercritical water. The specific aims are: 1) to determine the rates, extent, and mechanisms of model waste conversion and the resulting products (including toxic by-products) for ranges of operating conditions (e.g. temperature, pressure, reaction time, oxygen potential, and type of waste) of scientific and practical interest, and 2) to use this information to improve current understanding of how to apply supercritical water oxidation to destruction of toxic chemicals, remediation of contaminated soils, and cleanup of dilute aqueous wastes. Researchers are particularly focused on using model compounds and have selected toxic components for detailed study in the first phase of this work. Wastes containing mixed solvents and inorganic salts are particularly important in pump-and-treat remediation procedures. Multiphase feeds involving organics and salts dissolved in water and absorbed soil particles are also characterized. This specific approach involves a coupled experimental and theoretical modeling effort to determine global kinetic expressions phase equilibria and partitioning and to interpret mechanistic pathways. The new kinetic data obtained on the oxidation and hydrolysis of model compounds in supercritical water permits the evaluation of this process as a technology for remediation. For the first time, quantitative kinetic measurements are being conducted on mixed feeds under isothermal conditions and the thermodynamic stabilities of partial oxidation and hydrolysis products are examined in light of their potential influence on reactor performance.