Separation and Recovery of Ions from Aqueous Media with Redox-Recyclable Metal-Complex Extractants

Colorado State University, Fort Collins CO

Investigators

Abstract

Proposal No.: CTS-0085892 Proposal Type: Investigator Initiated Renewal Principal Investigators: Steven H. Strauss Institution: Colorado State University Separation and Recovery of Ions from Aqueous Media with Redox-Recyclable Metal-Complex Extractants Development of methods for the selective and efficient extraction of ionic species from water and the recovery of the target ions in a minimal volume of secondary waste using one-electron, redox-active, recyclable molecular extractants continues along with an investigation of the underlying scientific principles. The "redox-recyclable" extractants are sterically demanding iron complexes which are shuttled between their neutral (deactivated) states and their monoanionic or monocationic (activated) states. New extractants with improved performance are being prepared, as are new composite ion-exchange materials made from them. Some of the latter will be activated and deactivated electrochemically, avoiding the need for chemical oxidants and reductants in the complete extraction/deactivation-stripping/reactivation cycle. Recovery schemes that allow the target ions to be isolated as crystalline salts, a truly minimal volume of secondary waste, are also being developed. The use of these new adsorbent materials for highly-sensitive FTIR or electrochemical real-time, in-pipe detectors for selected target ions is also being explored. The capabilities provided by this new separation technique can have a significant impact in environmental protection. Among the ions that have been selected for new extraction and/or detection processes are those that pose a direct threat to the environment, such as perchlorate (groundwater pollution in several western states), cyanide (runoff from many mining operations), dimethylarsenate (groundwater pollution), cationic pesticides such as monoquats, fluorinated surfactants (including perfluorooctylsulfonate, the manufacture of which has been recently discontinued because of its possible threat to human health). In addition, this project can contribute to the efficiency of important biotechnological processes. Other target ions also include selected pharmaceuticals such as penicillins, prostagladins, and methotrexate cations, because the new extraction processes will be efficacious for their isolation from reaction mixtures and fermentation broths generated in current manufacturing processes.