A comparison of the extraction of carrier-free176,177W and99Mo with that of U, Th, Am, Cm, La, Ce, Tm, Yb, Lu, and Hf into tri-n-octyl amine in toluene from nitric, phosphoric, and sulphuric acid media

A comparision of the extraction of carrier-free 176,177W and 99Mo with that of U, Th, Am, Cm, La, Ce, Tm, Yb, Lu and Hf into Aliquat 336 in toluene from nitric, phosphoric, and sulphuric acid media

Carrier-free 176,177W and 99Mo have been extracted from 0.1-5.0M nitric, phosphoric and sulphuric acids into 0.22M Aliquat 336, CH3NR3Cl, in toluene. Their extraction properties have been compared to hafnium, to the lanthanides lanthanum, cerium, thulium, ytterbium and lutetium, and to the actinides americium, curium, thorium and uranium. From nitric acid solutions the extracted species of tungsten and molybdenum at low concentrations are probably CH3NR3· HMO4, where M=Mo or W. At higher nitric acid concentrations the extracted species are most likely similar to those of uranium, i.e. (CH3NR3)2·MO2(NO3)4 and possibly CH3NR3·MO2(NO3)3. For the extraction from phosphoric acid solutions the major extracted complex is most likely CH3NR3·MO2(H2PO4)3, while the minor extracted complex may be (CH3NR3)2·MO2(H2PO4)4 or even the more hydrolysed species CH3NR3·HMO4. From sulphuric acid solutions the extraction of molybdenum and tungsten has similarity with the extraction of uranium and thorium, although the decrease with acid concentration is slower.

Chemistry of Superheavy Elements

The number of chemical elements has increased considerably in the last few decades. Most excitingly, these heaviest, man-made elements at the far-end of the Periodic Table are located in the area of the long-awaited superheavy elements. While physical techniques currently play a leading role in these discoveries, the chemistry of superheavy elements is now beginning to be developed. Advanced and very sensitive techniques allow the chemical properties of these elusive elements to be probed. Often, less than ten short-lived atoms, chemically separated one-atom-at-a-time, provide crucial information on basic chemical properties. These results place the architecture of the far-end of the Periodic Table on the test bench and probe the increasingly strong relativistic effects that influence the chemical properties there. This review is focused mainly on the experimental work on superheavy element chemistry. It contains a short contribution on relativistic theory, and some important historical and nuclear aspects.

A method for preparation and purification of 234Th

An improved method to recover 234Th from depleted uranium has been developed. The method is based on solvent extraction and ion-exchange separations. The final thorium fraction has a high specific activity, about 1-3 PBq/mol Th, which makes it well suited for investigations, where a low thorium concentration is essential. The method is comparably fast, with a total processing time of 2 days. Another advantage is that the uranium fraction can be used as a 234Th generator for several years.