Electrochemical and spectroscopic studies of some less stable oxidation states of selected lanthanide and actinide elements
Simultaneous observation of electrochemical and spectroscopic properties (spectroelectrochemistry) at optically transparent electrodes (OTE's) was used to study some less stable oxidation states of selected lanthanide and actinide elements. Cyclic voltammetry at microelectrodes was used in conjunction with spectroelectrochemistry for the study of redox couples. Additional analytical techniques were used. The formal reduction potential (E/sup 0/') values of the M(III)/M(II) redox couples in 1 M KCl at pH 6 were -0.34 +- 0.01 V for Eu, -1.18 +- 0.01 V for Yb, and -1.50 +- 0.01 V for Sm. Spectropotentiostatic determination of E/sup 0/' for the Eu(III)/Eu(II) redox couple yielded a value of -0.391 +- 0.005 V. Spectropotentiostatic measurement of the Ce(IV)/Ce(III) redox couple in concentrated carbonate solution gave E/sup 0/' equal to 0.051 +- 0.005 V, which is about 1.7 V less positive than the E/sup 0/' value in noncomplexing solution. This same difference in potential was observed for the E/sup 0/' values of the Pr(IV)/Pr(III) and Tb(IV)/Tb(III) redox couples in carbonate solution, and thus Pr(IV) and Tb(IV) were stabilized in this medium. The U(VI)/U(V)/U(IV) and U(IV)/U(III) redox couples were studied in 1 M KCl at OTE's. Spectropotentiostatic measurement of the Np(VI)/Np(V) redox couple in 1 M HClO/sub 4/ gave an E/sup 0/' value of 1.140 +- 0.005 V. An E/sup 0/' value of 0.46 +- 0.01 V for the Np(VII)/Np(VI) couple was found by voltammetry. Oxidation of Am(III) was studied in concentrated carbonate solution, and a reversible cyclic voltammogram for the Am(IV)/Am(III) couple yielded E/sup 0/' = 0.92 +- 0.01 V in this medium; this value was used to estimate the standard reduction potential (E/sup 0/) of the couple as 2.62 +- 0.01 V. Attempts to oxidize Cm(III) in concentrated carbonate solution were not successful which suggests that the predicted E/sup 0/ value for the Cm(IV)/Cm(III) redox couple may be in error.
- Research Organization:
- Univ. of Tennessee, Knoxville, TN (United States)
- DOE Contract Number:
- AS05-76ER04447
- OSTI ID:
- 6364847
- Report Number(s):
- DOE/ER/04447-124; TRN: 81-010600
- Resource Relation:
- Other Information: Thesis
- Country of Publication:
- United States
- Language:
- English
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Spectroscopic and electrochemical studies of selected lanthanides and actinides in concentrated aqueous carbonate and carbonate-hydroxide solutions and in molten dimethyl sulfone
Spectroscopic and electrochemical studies of selected lanthanides and actinides in concentrated aqueous carbonate and carbonate-hydroxide solutions and in molten dimethyl sulfone
Related Subjects
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEAR CHEMISTRY
AMERICIUM COMPOUNDS
VALENCE
CERIUM COMPOUNDS
CURIUM COMPOUNDS
EUROPIUM COMPOUNDS
PRASEODYMIUM COMPOUNDS
SAMARIUM COMPOUNDS
TERBIUM COMPOUNDS
URANIUM COMPOUNDS
YTTERBIUM COMPOUNDS
ABSORPTION SPECTRA
ELECTROCHEMISTRY
OXIDATION
REDOX REACTIONS
SPECTROSCOPY
VOLTAMETRY
ACTINIDE COMPOUNDS
CHEMICAL REACTIONS
CHEMISTRY
RARE EARTH COMPOUNDS
SPECTRA
TRANSPLUTONIUM COMPOUNDS
TRANSURANIUM COMPOUNDS
400201* - Chemical & Physicochemical Properties
400702 - Radiochemistry & Nuclear Chemistry- Properties of Radioactive Materials