Reduction of Europium and Terbium at Dropping Mercury Electrode

Journal Article · Fri Jan 01 04:00:00 EST 1960 · Nippon Kagaku Zasshi (Journal of the Chemistry Society of Japan, Pure Chemistry Section)

DOI:https://doi.org/10.1246/nikkashi1948.81.5_739· OSTI ID:4088863

IWASE, Akio

The influences of pH upon the current-voltage curves and on the number of reducing electrons were studied for each ion(III) of europium and terbium. The polarogram was recorded under the following conditions: supporting electrolyte, 0.1M LiCI; maximum suppresser, 0.01% gelatin; concentration range of depolarizer, 10/sup -3/ to 10/sup -4/ mole/l; pH, 2 to 5; temperature, 25 deg C. In the case of europium a two-step wave due to the reduction of Eu/sup 3+/ yields Eu/sup 2+/ and Eu/sup 2+/ yields Eu/sup 0/, was observed. In the case of terbium, waves apart from the hydrogen waves were observed but the two-step wave (Tb/sup 3+/ yields Tb/sup 2+/ and Tb/sup 2+/ yields Tb/sup 0/) was not observ ed. These values of half-wave potential were --0.670 v (the first wave of europium, at pH 4.0), --1.945 v (the second wave of europium), and --1.818 v vs. S.C.E. (terbium, at pH 3.0), respectively. When pH of the solution was changed from 4.5 to 2.4, the half-wave potentials of europium (the first wave) and terbium shifted to the more negative side, and the first wave of europium changed from reversible to irreversible nature and the wave of terbium changed from irreversible to reversible nature (the plot of log i/(i/sub d/--i) against E/sub d-e/ of the wave of terbium is a straight line with a slope of 0.01 v, which coincides well with the theoretical value 0.02 v, in the case of three-electron reduction at lower pH range than 8). In the case of the second wave of europium, the plot of its ion i/i/sub d/ --i) against E/sub d-/i gives a straight line with a slope of 0.03 v. In both cases of europium and that of terbium, the limiting currents were diffusion-controlled. The values of diffusion current constants obtained were 1.50 plus or minus 0.01 (the first wave of europium), 3.02 plus or minus 0.03 (the second wave of europium) and 4.50 plus or minus 0.05 (terbium), respectively. The constant of diffusion current coincides with the theoretical value calculated approximately from the Ilkovic equation, using the diffusion coefficient of dysprosium ion (III), on the assumption that the reduction proceeds as Eu/sup 3+/ yields Eu/sup 2+/, Eu/sup 2+/ yields Eu/sup 0/, and Tb/sup 3+/ yields Tb /sup 0/. Accordingly, the number of reducing electrons of terbium must be three.

• Research Organization: Yamagata Univ., Japan
• Sponsoring Organization: USDOE
• NSA Number: NSA-15-010885
• OSTI ID: 4088863
• Journal Information: Nippon Kagaku Zasshi (Journal of the Chemistry Society of Japan, Pure Chemistry Section), Journal Name: Nippon Kagaku Zasshi (Journal of the Chemistry Society of Japan, Pure Chemistry Section) Journal Issue: 5 Vol. 81; ISSN 0369-5387
• Country of Publication: Country unknown/Code not available
• Language: Japanese

Related Subjects

CHEMISTRY
COLLOIDS
CONTROL
CROPS
DIFFUSION
DROPPING ELECTRODES
DYSPROSIUM
ELECTRODES
ELECTROLYTES
EUROPIUM
GELATINE
ILKOVIC EQUATION
IONS
LITHIUM CHLORIDES
MERCURY
REDUCTION
TERBIUM