The Potentials of the Uranium Three--Four and Five--Six Couples in Perchloric and Hydrochloric Acids

Detection of uranium(VI) in aqueous solution by a calix[6]arene modified electrode

“…The electrochemistry of UO 2þ 2 has been extensively studied in the past, primarily by polarography, published as early as the 1940s [24][25][26][27][28][29][30][31][32][33]. Two [25][26][27]29,30] or three [24,28] distinctive waves have been associated with the reduction of uranyl: the first wave was assigned to the reversible reduction of U(VI) to U(V), while the second corresponded to the further reduction of U(V) to U(IV).…”

“…Two [25][26][27]29,30] or three [24,28] distinctive waves have been associated with the reduction of uranyl: the first wave was assigned to the reversible reduction of U(VI) to U(V), while the second corresponded to the further reduction of U(V) to U(IV). In other cases, depended on the acidity and the nature of the supporting electrolyte, a third reduction wave appeared.…”

“…In other cases, depended on the acidity and the nature of the supporting electrolyte, a third reduction wave appeared. Under certain conditions the second wave merged with the third and corresponded to the reduction of U(IV) to U(III) [26,29,30]. Interestingly, most of these studies have employed mercury electrodes, which are inconvenient for assembling a robust sensor for uranyl.…”

Polarography of Uranium(IV) in Noncomplexing and Complexing Media. Amperometric Determination of Fluoride

“…The study of t h e polarography of uranium(1V) shou-ed t h a t perchlorate, chloride, and sulfanilate-buffered solutions behave essentially as noncomplexing media. Although it has been reported t h a t chloride ions complex with uranium(1V) ( I ) , Kritchevsky and Hindman (12) found that the half-wave potential of uranium(1V) cathodic wave Wave B gave a log plot with a slope of 40 mv., in poor agreement with the theoretical value of 59 or 30 for a 1-or 2-electron reversible transfer reaction, respectively. However, the proximity of wave C made examination of wave B difficult.…”

Characterization of uranium(VI) in seawater1

“…The electrochemical reduction of uranium(V1) to uranium (V) on the dropping mercury electrode at low pH produces a polarographic wave with a reversible half-wave potential at about -0.2 V vs. SCE (Harris and Kolthoff 1945;Weber et al 1953). The half-wave potential depends on ionic strength in perchloric (Kritchevsky and Hindman 1949;Elving and Krivis 1959), chloridic (Kritchevsky and Hindman 1949), and sulfuric (Elving and Krivis 1959) solutions. The dependence of the half-wave potential on the concentration of Cl-and SOd2-is due to the formation of labile uranyl complexes.…”