LDRD Final Report on Designed Ionophores for Liquid-Membrane Separation and Extraction of Metal Ions

摘要

New materials and processes for metal-ion separation and extraction based on selective transport of ions across membranes have been developed. Using molecular simulations, porphyrin-based ionophores (molecular ion-carriers) were designed for selectivity in complexing metal ions and other transport properties, such as solubility in organic or aqueous solution. Selectivity was designed into the carriers by controlling basicity, shape, and size of the ionophore specifically for extraction of heavy metals and radionuclides. Promising ionophores were synthesized and tested for application in two different extraction systems. In the first, a supported liquid membrane (SLM) separates two liquid phases--one containing waste and the other a liquid to which the specified metal ions are extracted. The ionophores selectively transport a specified metal ion through the intervening liquid layer to give a pure solution of the metal ion that is easily concentrated. In the second, metal ions were photoreduced to insoluble compounds or elemental metal particles. Separation of the metal particles leaves a pure metal precipitate.