Czechoslovak Journal of Physics

, Volume 49, Supplement 1, pp 603–609 | Cite as

Redox potentials of M(VI)/M(V) limiting carbonate complexes (M=U or Pu) at different ionic strengths and temperatures. Entropy and heat capacity

  • H. Capdevila
  • P. Vitorge
Chemistry of Actinide and Trans-actinide Elements


For waste disposal programs, actinide aqua ions and limiting complexes had been studied by cyclic voltametry. Measured redox potentials in non complexing media were modelled by using SIT and Taylor’s series expansions to the second order for ionic strength I, and temperature T, influences. These data treatments give standard values for redox potential Eo, corresponding ΔSo, ΔHo and ΔCp o of reactions, and excess values (variations of E’o, ΔS, ΔH and ΔCp with I) that can be deduced by using T influence on fitted SIT coefficients Δε. This methodology is used here at 5 to 70°C in 0.3 to 1.5 M Na2CO3 media (I=0.9 to 4.5M). Eo=0.191±0.015 (−0.779±0.010) V/SHE, ΔSo=−178±37 (−174±5) J. K−1. mol−1, ΔCp o=−516±744 (−414±176) J. K−1.mol−1 and Δε=−0.175±0.04+(2.1±2.0) 10−3 ΔT-(2.4±7.7) 10−5 (ΔT)2/2 (−0.91±0.10+(7.0±1.9)10−3 ΔT-(5.8±0.11) 10−5 (ΔT)2/2) kg.mol−1 are obtained at 25°C and I=0 for the MO2(CO3)3 4−+e→MO2(CO3)3 5− reaction where M=Pu (and U respectively), lg(β3 Vo3 VIo)= −12.6±0.3 (−14.65±0.17) is deduced. lgβ3 V = 3.1±1.4 (6.95±0.18) is proposed using published β3 VI values.


Uranium Redox Potential Plutonium Activity Coefficient Redox Couple 
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Copyright information

© Institute of Physics, Acad. Sci. CR 1999

Authors and Affiliations

  • H. Capdevila
    • 1
  • P. Vitorge
    • 1
  1. 1.CEA DCC/DESD/SESDSaclayFrance

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