NTE: The Use of Ionic Liquids for the Remediation of Wastewater Contaminated by Organic Halogens

Tufts University, Medford MA

Investigators

Abstract

ABSTRACT CTS-0086725 Botsaris, G. Tufts University This investigation deals with the coupling of a novel emerging technology and a serious environmental problem. The technology is based on the use of the minimally explored class of solvents, the room temperature ionic liquids (RTILs). In contrast to the molten inorganic salts, that have a high melting point, RTILs are melts of salts that are liquids at or below room temperature. These solvents are comprised entirely of ions and constitute a new class of solvents that are different in properties from the two classes of molecular solvents currently in use: water and organic liquids. The environmental problem concerns industrial wastewater effluents and groundwaters contaminated by halogenated organic compounds. These pollutants are highly toxic polychlorinated organics, such as polychlorinated phenols, dioxins, furans, PCBs, chlorobenzenes, etc. They are usually in low concentrations in the contaminated water, nevertheless they need to be removed with high efficiency. This investigation examines the selective extraction and concentration of these organic halogens by an RTIL. The unique properties of ionic liquids provide high selectivity and the large partition coefficients necessary for a very efficient extraction and concentration. In one of the subsequent options to be considered, the extracted contaminants are removed by back extraction to a concentrated aqueous phase or by adsorption onto a solid, where they are destroyed by known advanced oxidation techniques (AOTs). The most interesting idea to be studied, however, is the in situ destruction of the pollutants inside the ionic liquid, either by AOTs or electrochemically. The unique properties of the ionic liquids may provide a particularly favorable environment for these destruction processes. It is expected that the funding of this investigation will have ramifications beyond this particular application to other environmental problems.