Spectrophotometric Studies of the Uranyl-Lactate, -Malate and -Tartrate Systems in Acid Solution¹

Abstract

the two methods, while in poor agreement, are of the same order of magnitude. The value of Kv> calculated from pH titration may be in error because of formation of colloidal ferric hydroxide, since at points slightly beyond those used for calculation it was apparent that precipitation was taking place.The polarographic results depend upon the value of Kb, which may be in error.Bobtelsky and Jordan2 titrated an iron(III) solution with sodium citrate and found an increase in conductivity as the citrate was first added. In this titration the reactions represented by equations 8 and 9 would be expected to occur.The hydrogen ion produced by the second of these reactions would cause the pH to decrease. A check at the beginning of this titration showed that the pH did decrease, thus causing a conductivity increase as reported by Bobtelsky and Jordan.As the pH decreases one would expect relatively more of the material reacting to follow equation 8 and also the competitive reaction Cit-+ H+-> HCit-(15)The hydrogen ion concentration would then decrease, resulting in a conductivity decrease, which would continue even after all of the iron was complexed because of 15. Finally the conductivity would start to increase because of the addition of sodium citrate. The breaks in the conductivity curve would, according to this explanation, bear no direct relationship to the complex ion composition.Definite points of difference exist with Lingane5 and Meites6 with regard to the polarographic measurements. Lingane has claimed that the half-wave potential may be represented by an equation linear in pH from 4 to 12. The slope given by this equation is intermediate between the slopes of the two portions of our plot, and may have resulted from Lingane's larger but less detailed range of study. The differences with Meites arc harder to explain since we have found only a single wave at all pH values. Meites suggested that his differences from Lingane might be the result of the fact that Lingane had used 0.005% gelatin. We did not use gelatin, but have results corresponding more closely with those of Lingane. Acknowledgment.--We would like to express our thanks to Dr. S. R. Dickman who originally suggested the study of the citrate complexes of iron(II) and assisted by giving summer support to one of us (C.M.S.) from U.S. Public Health funds under his direction, as the investigation first started.

Cathodic Action of the Uranyl-Malate Complexes at the Dropping Mercury Electrode

“…If the ligand is hydrogen malate anion, the general equation for the reduction of uranyl hydrogen malate chelate may be written UO2(HA)p 2-p -5 e ~ UO2(HA)q 1-q -5 (p--q)HA- [1] The half-wave potential for the above reaction can be expressed as ( 6)…”

“…Because of a need for platinized-platinum electrodes of known absolute surface areas for use in catalyticelectrochemical studies, a number of electrodes were prepared under a variety of conditions, and the surface areas were measured using two different and independent methods. Although some studies have been carried out on the surface areas of electrodes of this type (1)(2)(3)(4)(5), no systematic investigations involving the preparation of such electrodes are known. We wished to prepare platinized-platinum electrodes reproducibly and, if possible, to determine the factors governing the specific surface areas (cm2/g) of the deposits.…”

The Coördination Chemistry of the Actinides.

“…The visible absorption spectra of solutions of uranyl tartrate and its double salts with sodium and pyridine had previously been recorded (343,344). For the uranyl-tartrate system in acid solutions, a mixture of complexes having uranyl: tartrate ratios of 1:1, 2:1, and 3:1 is present, the first predominating (145). In alkaline solutions, 1:1 and 3:2 complexes are formed (146).…”

“…The stoichiometries of the glycolate (2, 309), lactate (145,146), and malate (145, 146,206) complexes in solution have also been examined. Ascorbic acid forms in solution a 1:1 uranyl complex (174,196) which has been used for the colorimetric determination of uranium (443,450,508).…”

Extraction, Controlled-Potential Coulometric Method Specific for Uranium(IV)

“…APPARATUS AND REAGENTS Cells. The cells were of the conventional H-type, the larger patterned after that described by Lingane, Swain, and Fields (10). The cathode compartment was made from a widemouthed Erlenmeyer flask 75 mm.…”