Isotopic enrichment hydrogen

In TBP extraction, the yeUowcake is dissolved ia nitric acid and extracted with tributyl phosphate ia a kerosene or hexane diluent. The uranyl ion forms the mixed complex U02(N02)2(TBP)2 which is extracted iato the diluent. The purified uranium is then back-extracted iato nitric acid or water, and concentrated. The uranyl nitrate solution is evaporated to uranyl nitrate hexahydrate [13520-83-7], U02(N02)2 6H20. The uranyl nitrate hexahydrate is dehydrated and denitrated duting a pyrolysis step to form uranium trioxide [1344-58-7], UO, as shown ia equation 10. The pyrolysis is most often carried out ia either a batch reactor (Fig. 2) or a fluidized-bed denitrator (Fig. 3). The UO is reduced with hydrogen to uranium dioxide [1344-57-6], UO2 (eq. 11), and converted to uranium tetrafluoride [10049-14-6], UF, with HF at elevated temperatures (eq. 12). The UF can be either reduced to uranium metal or fluotinated to uranium hexafluoride [7783-81-5], UF, for isotope enrichment. The chemistry and operating conditions of the TBP refining process, and conversion to UO, UO2, and ultimately UF have been discussed ia detail (40). 

Figure 2.3 Changes in the heavy isotope content of oxygen and hydrogen in the urine with time after administration of The and 0 are diluted by the formation of H2O from oxidation of fuels and particularly that ingested in food and drink. The 0 in water is diluted from the production of CO2 via the oxidation of the fuels. The difference in the slopes indicates the rate of CO2 production. The label heavy isotope content is actually the isotopic enrichment. Physical activity, for example, increases fuel oxidation (i.e. respiration) and therefore greater dilution of...

The mode of rainfall and degree of evaporation influence groundwater composition. High degrees of evaporation result in enrichment of the heavier stable isotopes of hydrogen and oxygen (sections 9.3 and 9.6) and in higher concentrations of dissolved salts. 

Formation of Bonds between Hydrogen and C, Si, Ge, Sn, Pb 123 1.6.7. The Synthesis of Deuterium Derivatives 1.6.7.2. by Isotopic Enrichment Using Chemical Reactions... 

Mancini S. A., Couloume G. L., Jonker H., van Breukelen B. M., Groen J., VoUcering F., and Lollar B. S. (2002) Hydrogen isotopic enrichment an indicator of biodegradation at a petroleum hydrocarbon contaminated field site. Environ. Sci. Technol. 36( 11), 2464—2470. 

The mercury resonance line at X 2537 A, corresponding to the transition 6(3Pi) 6(1 So), has been used in most studies and monoisotopic photosensitisation has been specifically employed to examine the possible isotopic enrichment of the mercury compounds produced in these reactions. Thus, in the Hg monoisotopic photosensitised decomposition of methyl chloride " - the main products are methane, ethane, dichloroethane and hydrogen chloride together with calomel enriched with the ° Hg isotope. The following mechanism has been proposed " for the decomposition... 

Serianni, A S, Vuorinen, T, Bondo, P B, Stable isotopically-enriched D-glucose strategies to introduce carbon, hydrogen and oxygen isotopes at various sites, J. Carbohydr. Chem., 9, 513-541, 1990. 

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