Electromigration of Carrier-Free Radionuclides. 6. Iodide and Bromide Complexes of Carrier-Free ²⁰¹Tl(I) in Aqueous Solutions

Report on neptunium speciation by NMR and optical spectroscopies

“…Our room temperature result of logpi = 3.40 f 0.22 is most consistent with Itagaki et al (Itagaki et al 1992) and with Rosch et al (Rosch et al 1987), and given the uncertainty in our value and the literature value, possibly consistent with the result of Moskvin (Moskvin 1971). Values of logpl higher than these are not consistent with our experiments and may have resulted from the interferences noted above or from specific experimental problems.…”

“…Figure 1. Literature data for the log of the equilibrium constant, logP1, versus ionic strength, Im, for the hydrolysis reaction Np02+ + OH--and NELSON (1948), MOSKVIN (1971), SEVOSTYANOVA and-TURIN (1976), SCHMIDT et al (1980), MAYA (1983), BIDOGLIO et al (1985), LIERSE et al (1985), ROSCH et al (1987), NAGASAKI et al (1988), NAKAYAMA et al (1988), SULLJYAN et al (1991), ITAGAKI et al (1992), andNECK et al (1992). .…”

“…A summary of the first and second hydrolysis constants taken from the literature for Np(V) is given in Table 1, and a graph of the first hydrolysis constant (logp1) as a function of ionic strength is shown in Figure 1 (Krause and Nelson 1948;Moskvin 1971;Sevost'yanova and Khalturh 1976;Schmidt, et al 1980;Maya 1983;Bidoglio et al 1985;Lierse et al 1985;Rosch et al 1987;Nagasaki et al 1988;Nakayama et al 1988;Itagaki et al 1992;Neck et al 1992). The first hydrolysis constant measured at 25OC is seen to vary by four orders of magnitude.…”

Impact of the formation of NpO{sub 2} and Np{sub 2}O{sub 5} on the Np solubility in YM waters

“…Np(V) solubility-limiting solids include Np2O5(c), NpOzOH(am), and, in high ionic strength carbonate media, the so-called double carbonate salts Nal-2xNp02(C03)x (x=l to 3) (Volkov et al, 1979(Volkov et al, , 1981Neck et al, 1994Neck et al, , 1995. In the absence of carbonates, the solution speciation of Np(V) is dominated by the highly soluble Np02+, which does not hydrolyze readily below a pH of 10 (Moslwin, 1971; Rosch et al, 1987;Neck et al, 1992;Tait et al, 1995). In 5-13 type waters, the carbonate-complexed Np(V) species of importance includes NpO2CO3-, where the higher carbonate complexes are not strong enough to be predominant, even at higher temperatures .…”