Thorium transfer

In the Acid-Thorex process, fluoride ion should be added to the thorium partitioning solution (1BX) to decrease thorium transfer to the uranium stripping column, particularly where highly radioactive feeds are used. This fluoride ion addition then decreases the precipitation of thorium-DBP in the uranium stripping column. Also, the partition cycle should be the first cycle in the Acid-Thorex process to allow separation of thorium from DBP. 

Gas-liquid volumetric mass transfer coefficient correlations, for airlift reactors, 15 704-705t Gas lubrication, 15 252 Gas mantles cerium in, 5 689 thorium in, 24 757 Gas masks, 5 832-835 Gas meter provers, liquid displacement, 11 652... 

Upon coordination via oxygen, as in uranyl sulfoxide complexes and thorium nitrate sulfoxide complexes, the positive charge on sulfur is virtually unaltered (19), whereas coordination via sulfur, as in palla-dium(II) sulfoxide complexes, causes an increase in the positive charge, as a result of transfer of electron density from the sulfur atom to the metal center (19, 373). 

M. Genet, V. Brandel, M.-P. Lahalle, and E. Simoni, Electronic energy transfer between coumarin 460 and Eu3+in thorium phosphate xerogel, C. R. Acad. Sci. Paris 311 (Series II), 1321-1325 (1990). 

The transport of atmospherically deposited thorium from soil to plants is low. The soil to plant transfer coefficients (concentration in dry plant to concentration in dry soil) were estimated to be 10 to 7x10 by Garten (1978) and 0.6x10 for thorium-232 by Linsalata et al. (1989). The root systems of grasses and weeds adsorb thorium from the soil but the transport of thorium from the root to the aboveground parts of the plant is not very extensive, as indicated by 100-fold higher concentrations of all three isotopes (thorium-228, thorium-230, and thorium-232) in the root than in the aboveground parts of the plant (Taskayev et al. 1986). However, Ibrahim and Whicker (1988)... 

Both Pu and Th will probably enter the skeleton and other internal tissues predominantly from inhalation. This statement is based on the fact that in the field, Pu and Th demonstrate similar transfers from soil to small mammals and laboratory studies demonstrate similar metabolic characteristics (1,3,23). Soil chemical behavior is also similar (20). As demonstrated in Table I, natural Th in human bone originates largely from inhalation, even assuming that adsorption from the diet is 0.1%. Another strong agrument for the importance of inhalation is found in tissue distributions of Th-232 and Th-230 in humans. Table V summarizes work by Wrenn, et al. (53) which shows that lungs of non-occupationally exposed individuals contains burdens of Th isotopes comparable to the skeleton. Thorium-228 distributions are different from Th-230,... 

As the relative transfer coefficients from soil to plants and from diet to the blood increase, ingestion takes on more importance. This certainly appears to be the case for U. It may be that ingestion will be more important for Am and Cm than for Pu or thorium. Neptunium remains in enigma because of the paucity of data. 

The closed-shell system thorium(IV) shows no electron transfer satellites (15). Protactinium is too rare and too radioactive to be measured by us, but certain uranyl compounds such as RbUC>2(02N0)3 show satellites about 3.5 eV above /(IJ4/5/2) and 7(U4/7/2) probably due to electron transfer to the empty 5/ shell. The somewhat peculiar photo-electron spectra of uranium compounds are further discussed Chapter IIF. 

MORE melting and dehydration in serpentinized peridotite was illustrated in Section 3.17.5.4. Here, an example of the effects on trace-element transfer as a function of fluid rock ratios is illustrated. The layered structure of the oceanic lithosphere may cause the fluid rock ratio in the sedimentary layer to be greater than one (as fluids from the underlying mafic and peridotitic layers must rise through the sediments). Thus, some of the trace elements (e.g., beryllium, thorium) commonly considered to be only efficiently mobilized by melts could also be quite effectively mobilized by fluids, if the entire subducted lithosphere is considered. 

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