Original scientific paper

Contribution to the Electrochemistry of Uranium(V) in Carbonate Solutions

J. Čaja ; Laboratory of Electrochemistry, Institute »Ruder Boskovic«, Zagreb, Croatia, Yugoslavia
V. Pravdić ; Laboratory of Electrochemistry, Institute »Ruder Boskovic«, Zagreb, Croatia, Yugoslavia

Abstract

Oxidation - reduction reactions of uranium(V) and (VI) in
sodium and caesium carbonate solutions at high pH were studied
using the chronopotentiometric technique. Uranium(V) formed by
electrolysis of uranium(VI) at constant potential is stable, its rate
of disproportionation negligible. The apparent standard redox
potential (uncorrected) of the U(VI) /U(V) couple was found to be
- 0.760V vs. S. C. E. in 1 M Na2C03 and pH = 11.5. The uncorrected
overall transfer coefficients for the oxidation of U(V) and rereduction
of U(VI) were: 0.64 and 0.42 in 1 M Na2C03, and 0.47 and
0.47 in 0.5 M Cs 2C03• The formal rate coefficients for the oxidation
and re-reduction of 1 mM bulk U(V), referred to the N. H. E. were:
2.1 X 10-9 and 2.7 X 10-s cm/sec in 1 M Na2C03, and 8.0 X 10-9
and 1.1 X 10 -s cm/sec in 0.5 M Cs2C03• Narrow concentration limits
for the solubility of uranium complexes and the relatively low
concentration sensitivity of the chronopotentiometric technique
render precise quantitative calculations and corrections for double
layer effects or counter-ion association rather difficult.

Keywords

Hrčak ID:

207939

URI

https://hrcak.srce.hr/207939

Publication date:

1.2.1970.

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