| SCWO is being considered as a method of waste destruction for municipal, industrial, and military waste including chemical weapons and fuels. Although a great deal of research has focused on the determination of destruction efficiencies of organic compounds in SCW, interest is currently focused on understanding solvating properties of SCW and elucidating molecular-level interactions that take place in SCWO. This work is an investigation of solvent effects on reactivity in a wide variety of SCFs. Since SCWO is not well understood on the molecular level, a broad understanding of different reaction systems is necessary to ultimately elucidate the fundamental influence of the SC solvent on reactions involved in the SCWO process. The behavior in lower-temperature SCFs and SCW compared to what is known for normal liquids is pivotal to understanding what is unique to reactivity in SCFs and in turn what is distinctive of SCW. To this end, a variety of reactivity has been studied in this work: diffusion-controlled, near diffusion-controlled, kinetically controlled, ionic, neutral, and catalytic. Solvents include both subcritical and supercritical water, carbon dioxide, ethane, fluoroform, and pentane. Primarily, the spectroscopic techniques laser flash photolysis and pulse radiolysis have been used, however, batch reactivity has also been examined. All results are compared to what is observed or predicted in normal liquids and conclusions are drawn with regard to the SCF solvation environment.;The major findings in this work are first, that the triplet-triplet annihilation of anthracene, which is a diffusion-controlled reaction in normal liquids, is unhindered by the SCF and reacts at the diffusion-controlled limit in SCW. Second, benzophenone triplet quenching with amines (TEA, DABCO), which is near diffusion-controlled in normal liquids, is found to be below the diffusion-controlled limit in SCF CO... |
