Thermodynamic modeling of trivalent Am, Cm and Eu-citrate complexation in concentrated NaClO₄media

Abstract

Citric acid dissociation constants / Am-Cm-Eu-citrate complexation / Pitzer parameters / Extraction / High ionic strengthSummary. The dissociation constants of citric acid (Cit), and the stability constants of Am 3+ , Cm 3+ and Eu 3+ with Cit were determined as a function of ionic strength (NaClO 4 ) using potentiometric titration and an extraction technique, respectively. The results have shown the presence of both 1 : 1 and 1 : 2 complexes under the experimental conditions. A thermodynamic model was constructed to predict the apparent stability constants at different ionic strengths by applying the Pitzer ionic interaction parameters β (0) , β (1) , and C φ which were obtained to fit the experimental data. Thermodynamic stability constants of M(Cit) and M(Cit) 2 3− (where M = Am 3+ , Cm 3+ or Eu 3+ ) were calculated to be log β 0 101 = 9.91 ± 0.10, log β 0 102 = 14.47 ± 0.14 for Am 3+ , log β 0 101 = 9.53 ± 0.16, log β 0 102 = 14.46 ± 0.16 for Cm 3+ and log β 0 101 = 9.82 ± 0.14, log β 0 102 = 13.31 ± 0.12 for Eu 3+ as obtained by extrapolation to zero ionic strength.

Curium(iii) citrate speciation in biological systems: a europium(iii) assisted spectroscopic and quantum chemical study

“…Literature data on the complexation of trivalent actinides and lanthanides with citrate are quite numerous. 9,[13][14][15][16][17][18][19][20][21][22][23][24][25][26][27]28,29 While europium(III) is well studied, 9,15,[19][20][21][22]24,25 less work was conducted with curium(III). 9,15,18,24,26 Luminescence spectroscopic data of the complexes formed were reported once for europium(III) 9 but to the best of our knowledge not for curium(III).…”

Experimental and Modeling Study of Interactions of Rare Earth Elements (REE) Pr(III) and Nd(III) with Citrate and Oxalate: Implications to the Mobility of Actinides and REE and Their Extractions

“…Our experiments indicate that the solubilities of Pr 2 (C 2 O 4 ) 3 •10H 2 O and Nd 2 (C 2 O 4 ) 3 •10H 2 O are much higher than those predicted with the model including all of the respective aqueous binary complexes of REE with oxalate and citrate [1][2][3]. This suggests that the ternary complexes should be required.…”

“…The solid phases, Pr 2 (C 2 O 4 ) 3 •10H 2 O and Nd 2 (C 2 O 4 ) 3 •10H 2 O, provide the sources for both REE and oxalate. In addition, we use Pr 2 (C 2 O 4 ) 3 •10H 2 O and Nd 2 (C 2 O 4 ) 3 •10H 2 O as the respective analogs to Pu 2Our experiments indicate that the solubilities of Pr 2 (C 2 O 4 ) 3 •10H 2 O and Nd 2 (C 2 O 4 ) 3 •10H 2 O are much higher than those predicted with the model including all of the respective aqueous binary complexes of REE with oxalate and citrate [1][2][3]. This suggests that the ternary complexes should be required.…”

An Advanced TALSPEAK Concept for Separating Minor Actinides. Part 1. Process Optimization and Flowsheet Development

“…The formation of the mixed-ligand ternary aqueous complexes was not taken into consideration because of the lack of reported relevant thermodynamic data. For each system, the speciation model and the corresponding literature sources [36][37][38][39][40][41][42][43][44][45][46] are summarized in the tables in Figure 2. Extraction equilibria were not considered in this analysis.…”