Synergistic extraction of REE and TPE from nitric acid solutions with chlorinated cobalt dicarbollide-dibutyl hydrogen phosphate mixture in a polar diluent

The extraction of Ce(III), Am(III), and Eu(III) from nitric acid solutions with chlorinated cobalt dicarbollide (CCD), dibutyl hydrogen phosphate (HDBP), and their mixtures in a polar diluent, m-nitrobenzo-trifluoride, was studied. The extraction with CCD-HDBP mixture is characterized by considerable synergistic effect. Its maximal value is close to 40 at HDBP to CCD molar ratio of 5-8 for all the metals under consideration. We believe that this synergistic effect is caused by formation of a complex acid from HDBP and CCD. This complex acid is more hydrophobic and more acidic than the initial reagents. In extraction of the metals from strongly acidic solutions, the HDHP to CCD ratio corresponding to optimal extraction decreases. This effect can be attributed to displacement of HDBP molecules from the extractable complex with HNO3 molecules. © 2007 Pleiades Publishing, Inc.