Tables of ion interaction coefficients

2 Ion interaction coefficients versus equilibrium constants for ion pairs 

It should be mentioned that complex formation may also occur between highly charged complexes and the counterion of the ionic medium. An example is the stabilisation of the complex ion, 1102(003)3 , at high ionic strength, see for example Section V.7.1.2.1.d (p. 322) in the uranium review [1992GRE/FUG]. 

It should be noted that ion interaction coefficients tabulated in Table B-4, Table B-5 and Table B-6 may also involve ion pairing effects, as described in Section B.3. In direct comparisons of ion interaction coefficients, or when estimates are made by analogy, this aspect must be taken into account. 

A 3 + Am cf 0.23 0.02 The s(An, Cr) for An = Am and Cm is assumed to equal to s(Nd , Cr) which is calculated from trace activity coefficients of Nd ion in 0-4 m NaCl. These trace activity coefficients are based on the ion interaction Pitzer parameters evaluated in [1997KON/FAN] from osmotic coefficients in aqueous NdCh -NaCl and NdCls - CaCl2. 

NpSCN Cf 0.76 0.12 Estimated in [2001LEM/EUG] by analogy with As of the corresponding U(IV) reaction. 

In some cases, the ionic interaction can be better described by assuming ion interaction coefficients as functions of the ionic strength rather than as constants. Ciavatta [80CIA] proposed the use of Eq. (B.24) for cases where the uncertainties in Table B-4 and Table B-5 are 0.03 kg-mol or greater. 

For these cases, and when the uncertainty can be improved with respect to the use of a constant value of e, the values s, and Ej given in Table B-6 should be used. 

In direct comparisons of ion interaction coefficients, or when estimates are made by analogy, this aspect must be taken into account. 

X These coefficients were not used in the NEA-TDB uranium review [92GRE/FUG] because they were evaluated by Ciavatta [80C1A] without taking chloride and nitrate complexation into account. Instead, Grenthe er a/, used 8(U02, X) = (0.46 + 0.03) kg-moP, for X = CP, CIO4 and NO3.  

B Estimated in [2001LEM/FUG] by assuming e(PuSCN C104) 6(AmSCN C10 ). 

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