chemical thermodynamics of neptunium and plutonium - U.S. ...

622 A. Discussion of selected references[69MET/GUI]This is a solvent extraction study of the hydrolysis of Pu(IV) for an aqueous mediumof ionic strength 1.0 M (H/LiClO 4 ). No values for the hydrolysis constants are derivedin this paper.[69MOS]This publication is a compilation of stability constants of actinide complexes with variousligands. Values for nitrate, sulphate, carbonate and phosphate complexes, as determinedin previous work, published and unpublished, were reported together withthe author’s estimates. For the phosphate system, constants for Np(III) complexes withH 2 PO − 4were included, estimated on the basis of the results for Pu(III), Am(III) andCm(III) published in a later paper [71MOS4]Np 3+ + nH 2 PO − 4Å Np(H 2 PO 4 ) 3−nn(A.35)log 10 β n (A.35, n = 1, unreported temperature, I → 0) = 2.40log 10 β n (A.35, n = 2, unreported temperature, I → 0) = 3.73log 10 β n (A.35, n = 3, unreported temperature, I → 0) = 5.64log 10 β n (A.35, n = 4, unreported temperature, I → 0) = 6.2and estimates at I = 0 for the Pu(III) constants later reported in [71MOS4]:Pu 3+ + nH 2 PO − 4Å Pu(H 2 PO 4 ) 3−nn(A.36)log 10 β n (A.36, n = 1, unreported temperature, I → 0) = 2.39log 10 β n (A.36, n = 2, unreported temperature, I → 0) = 3.70log 10 β n (A.36, n = 3, unreported temperature, I → 0) = 5.63log 10 β n (A.36, n = 4, unreported temperature, I → 0) = 6.2Since the experimentally determined constants for the Pu(III) in [71MOS4] have beenrejected in the present review, the same holds for the corresponding Np(III) complexes.Moskvin includes also constants for complexes of Np(VI) with both H 2 PO − 4and HPO 2−4and for Pu(VI) with HPO 2−4, reported to have been obtained in a solventextraction study at an ionic strength 0.5 M.NpO 2+2+ H 2 PO − 4Å NpO 2 H 2 PO + 4(A.37)log 10 β(A.37, unreported temperature, I = 0.5M) = 1.70log 10 β(A.37, unreported temperature, I → 0) = 2.33NpO 2+2+ HPO 2−4Å NpO 2 HPO 4 (aq) (A.38)