Distribution ratio of U

Nevertheless, extraction tests by the addition of the primary acidic compound (hexanoic acid coming from the degradation of A, . V- diet h y I -2 - he x y I hexanamide) were performed by Musikas (189) the distribution ratios of U(VI) and Pu(IV) at 0.5 and 4 mol k 1 HN03 remained constant, even for amounts related to a degradation of 0.2 MGy. 

Figure 5. Distribution ratios of U (VI), Pu (IV), and Am (III) for HDBP and H2MBP in 2-EHOH aqueous phase = 3.5M HNOs, T = 50°C.

A large adduct formation constant increases the hydrophobicity of the metal complex and thus the distribution ratio of the metal. This is commonly referred to as a synergistic effect. Figure 4.2 illustrates the extraction of the U02(TTA)2 complex from 0.01 M HNO3 into cyclohexane. Because the linear O-U-0 group is believed to have five to seven coordination sites, where only... 

Several tests using countercurrent separation in mixer-settler or centrifugal extractors with simulated and genuine high-level waste showed that the recovery of An(III, IV, VI) is quantitative. The back extraction of An(III) was complete. These early flow sheets were not designed to strip U(VI) and Pu(IV). The distribution ratios of these ions at low acidities are lower than those measured with CMPO and one can guess that the stripping... 

Distribution ratios of ruthenium evolved irregularly with the dose absorbed. With some amides, after a high increase (factors of 20-30 up to 1 MGy), the extraction decreased, as shown for Pu(IV), but more drastically (factors of 10 to 300 from 1 to 2 MGy) (188, 191). Other authors indicated an absence of ruthenium extraction (Z)Ru < 10-2) over the entire range studied (0 to 1.8 MGy) (194). On the other hand, the decontamination factors for U and Pu with respect to ruthenium(III) employing irradiated amides were comparable to the corresponding values with TBP (191). 

FIG U RE 8.8 Effect of radiation dose on the distribution ratios of various actinides from 0.5 M (—) or 5 M HN03 (-) by 1 M DMDBHDEMAin terr-butylbenzene. (Redrawn from Thiollet, G., Musikas, C., Solvent Extr. IonExch. 7(5) 813-827, 1989. With permission.)... 

The distribution ratios of the extraction of U(VI) and Th(IV) into a highly hindered phosphate extractant, T(4-MPe-2)P,... 

Figure 5. Distribution coefficients of U (VI) between 5M aqueous phosphoric acid and mixture of HDEHDTP and neutral oxygen donors in solution in do-decane as a function of the reagent concentration ratio (1) 0.5M (HDEHDTP + POX 11), (2) 0.5M (HDEHDTP + TOPO), (3) 0.5M (HDEHDTP + TBP).

Using the 2D-HSQC peak volumes from backbone e-e, e-u, u-e, and u-u -CH2-OR correlations in Figure 39(a) and from chain-end e- and U-CH2-OH correlations in Figure 39(b), they derived an internal -CH2-OR/terminal -CH-OH peak volume ratio of 203 1. Similarly, the direct integration of crosspeak volumes in the spectmm shown in Figure 39(a) gave the monomer distribution ratio of 4.76 3.76 1.00 for butanediol adipate diphenylmethane units. 

Conceptual Flowsheet for the Extraction of Actinides from HLLW. Figure 5 shows a conceptual flowsheet for the extraction of all the actinides (U, Np, Pu, Am, and Cm) from HLLW using 0.4 M 0< >D[IB]CMP0 in DEB. The CMPO compound was selected for this process because of the high D m values attainable with a small concentration of extractant and because of the absence of macro-concentrations of uranyl ion. Distribution ratios relevant to the flowsheet are shown in previous tables, IV, V, VI, and VII and figures 1 and 2. One of the key features of the flowsheet is that plutonium is extracted from the feed solution and stripped from the organic phase without the addition of any nitric acid or use of ferrous sulfamate. However, oxalic acid is added to complex Zr and Mo (see Table IV). The presence of oxalic acid reduces any Np(VI) to Np(IV) (15). The presence of ferrous ion, which is... 

Different locations of parent elements. and Th are generally located in minor phases within host rocks. Due to different U/Th ratios in these phases, recoil from the two chains may be affected by different surrounding matrix characteristics or mineral sizes. Not only might the primary distribution of U and Th be different, but earlier weathering or alteration may also have redistributed U and Th. This is discussed further below. 

It follows that a small periodic perturbation applied to a system, the eigenstates of which are densely distributed in energy, leads to a power dissipation quadratic in the perturbation. For such a linear system it is possible to define an impedance Z(co), the ratio of the force V to the response Q, where all quantities are now assumed to be in standard complex notation, V = Z(u>)Q. The instantaneous power is VQR u )/ Z oj), where R(co), the resistance, is the real part of Z(lu). 

The apparent retinal influx clearance,. Kin,retina expressed as mL/(min g retina), of the test substrate labeled with either [3 H] or [14C] from the circulating blood to the retina is determined by integration plot analysis. In brief, rats are anesthetized, followed by injection of the test substrate (e.g., an [3H]-labeled compound, about 10 /u.Ci/head) into the femoral vein. After collection of plasma samples, rats are decapitated and the retinas removed. The retinas are dissolved in 2 N NaOH and subsequently neutralized with 2 N HC1. The radioactivity of retinal cell lysates is measured by liquid scintillation spectrometry. As an index of the retinal distribution characteristics of the radiolabeled test substrate, the apparent retina-to-plasma concentration ratio (Vd) as a function of time is used. This ratio [Vd(Q] (mL/g retina) is defined as the amount of [3H] per gram retina divided by that per milliliter plasma, calculated over the time-period of the experiment. The Kjn,retina can be described by the following relationship ... 

If reprocessing of spent Th fuels is needed in the future, many drawbacks of the Thorex process can be avoided by using A, A -dialkylamides instead of TBP. It is known from studies of Pu(IV)-U(VI) separation with amides that U(VI)-Th(IV) separation in acidic medium is easier than with TBP. The advantages of amides over phosphates could probably be considered more freely for Thorex than for Purex plants because no Thorex plant has been built yet. The extraction behavior of Pa(V) has not been yet investigated but in view of the general chemical properties of the two extractants, smaller distribution ratios are expected with the A, A -dialkyl-amides. 

Concentration Dependence Studies. The variation of the product distribution as a function of total metal concentration, at a fixed ruthenium rhodiumrtriethylamine ratio of 10 1 10, under the standard reaction conditions of 1000 atm and 230°C is illustrated in Figure U. Thus the rate of product formation increases linearly with respect to increasing concentration up to ca 2.5 mmoles total metal above which the rate levels off. A plot of turnover (total carbon monoxide... 

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