Environmentally benign processing using supercritical fluids

Supercritical fluids are emerging as the favorite processing medium for a variety of processes including extraction, material modification, reaction, polymerization and waste destruction. Supercritical water and CO₂ possess inherent environmental advantage over other conventional solvent alternatives. This dissertation focuses on the use of supercritical fluids for environmentally benign processing.; Chapter 2 focuses on supercritical water oxidation, kinetics of oxidation of toxic organic compounds in supercritical water and addition of a catalyst/inorganic salt in the process. It also describes a new reactor design for the process. Chapter 3 describes the dye solubility in supercritical carbon dioxide and modeling the effect of hydrogen bonding when co-solvents are used. These results can be used in optimizing supercritical dyeing processes. Chapter 4 discusses a study on solubility of sulfur in supercritical water using Raman spectroscopic data and an equation of state involving hydrogen bonding. Chapter 5 describes an equation of state framework for modeling the hydrogen bonding in organic systems that can be applied for systems at ambient as well as systems at supercritical conditions. Alkanols and alkanol-alkanes mixtures are used as model compounds. This framework can be easily extended to biopolymers in aqueous systems. Chapter 6 describes the phase equilibria of mixtures containing ionic liquids, carbon dioxide and naphthalene. Distribution coefficient of naphthalene between CO₂ and ionic liquid is presented. It also describes the binary ionic liquid/CO₂ phase behavior.