Metal cation complexation and separation with macrocyclic polyether ligands

Date

2004-12

Journal Title

Journal ISSN

Volume Title

Publisher

Texas Tech University

Abstract

At Hanford, Washington, the Department of Energy maintains a site that contains approximately 6x10^7 gallons (2 x l0^8 liters) of waste left over from the development of nuclear weapons after WWII. This volume of material is too great to be stored in Yucca Mountain. Separation of the high-level radionuclides from the bulk of the material will allow the remainder to be treated and disposed of as low-level waste. Once separated, the high-level nuclides are then available for use in commercial applications, such as medical imaging and remote power plants.

This study explores the use of crown and lariat ethers for the separation of metal ions. A large number of compounds varying in specific structural aspects are studied using isothermal titration calorimetry (ITC), which directly determines the association constant, stoichiometry, and enthalpy of each metal-ligand system. Augmenting the ITC study is the intense study of a small selection of compounds. These compounds are studied under various conditions using a variety of techniques, such as ion-selective electrodes (ISE) and solvent extraction (SE), allowing for a fuller understanding of their association behavior.

The presence of metal ion is our world is ubiquitous. Some of these metals are benign, or even necessary for life. Others are harmful in minute quantities. The ability to selectively remove specific metal ions from waste streams, the environment, and our bodies will be an important process in years to come.

Description

Keywords

Solvent extraction, Radioactive waste disposal, Crown ethers -- Industrial applications, Ion selective, Electrodes, Lariat ethers -- Industrial applications, Metal ions -- Separation, Calorimetry, Complex compounds

Citation