[en] The extraction seperation of La and Sm by benzyldibutilamyne (BDBA) from an aqueous solution containing 6 mol*dm^-3 NaNO₃ and 0.5 mol*dm^-3 HNO₃ is not very efficient. It may remarkebly be improved by addition of a complexing agent, 2-hydroxyethylenedyaminetriacetic acid (HEDTA). The effect of preferential La extraction into the organic phase together with the effect of preferential complexation of Sm in the aqueous phase may lead, by proper choice of the complexing agent concentration, to a 7-10 fold increase in α_LA/Sm values. The procedure described here enables fairly good separation of a major from minor elements. (author) 16 refs.; 9 figs.; 2 tabs

No abstract available

[en] Thorium content was analyzed by titrimetric method using HEDTA as titrant and SPADNS indicator to know precision value and accuracy of thorium analysis result in low concentration (mg/L). Analytical solution used is thorium standard solution 1000 mg/L. The analysis was performed by adjusting the pH of the analytical solution between 2.0 - 3.0 by adding 1 M NaOH solution and the Dihydroxy-2-(4-sulfophenylazo)-naphthalene-3,6-disulfonic acid trisodium salt (SPADNS) indicator. The titration was then carried out using 0.01 M ethylenediamine-N, N', N'-triacetic acid (HEDTA) solution until the end point marked by the color change of the solution from violet to scarlet. From the analysis of standard thorium solution 1000 mg/L with the analytical solution volume of 25 mL (25 mg Th) measured thorium concentration of 955.177 mg/L with standard deviation (SD) of 20.124 mg/L, RSD of 2.107 % and accuracy of 4.482 %. While the result of analysis with 10 mL analytical solution volume (10 mg Th) thorium concentration measured equal to 976,720 mg/L, SD equal to 7,458 mg/L, RSD equal to 0,764 % and accuracy equal to 2,286 %. Thorium analysis results with titrimetric with analytical solution containing 10 mg Th more precision and has a higher accuracy than analytical containing 25 mg Th. (author)

[en] In the Advanced TALSPEAK process, the bis(2-ethylhexyl)phosphoric acid (HDEHP) extractant used in the traditional TALSPEAK process is replaced by the extractant 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester (HEH[EHP]). In addition, the aqueous phase complexant and buffer used in traditional TALSPEAK is replaced with the combination of N-(2-hydroxyethyl)ethylenediamine-N,N’,N’-triacetic acid (HEDTA) and citric acid. In order to evaluate the possible impacts of gamma radiolysis upon the efficacy of the Advanced TALSPEAK flowsheet, aqueous and organic phases corresponding to the extraction section of the proposed flowsheet were irradiated in the INL test loop under an ambient atmosphere. The results of these studies conducted at INL, led INL researchers to conclude that the scarcity of values of rate constants for the reaction of hydroxyl radical with the components of the Advanced TALSPEAK process chemistry was severely limiting the interpretation of the results of radiolysis studies performed at the INL. In this work, the rate of reaction of hydroxyl radical with citric acid at several pH values was measured using a competitive pulse radiolysis technique. This report describes those results and is written in completion of milestone M3FT-16IN030102028, the goal of which was to evaluate the role of organic acids in the protection of ligands from radiolytic degradation. The results reported here demonstrate the importance of obtaining hydroxyl radical reaction rate data for the conditions that closely resemble actual solution conditions expected to be used in an actual solvent extraction process. This report describes those results and is written in completion of milestone M3FT-16IN030102028, the goal of which was to evaluate the role of organic acids in the protection of ligands from radiolytic degradation.

[en] Complex formation between oxyethylethylenediamintriacetic acid and neodymium has been studied spectrographically. Composition of the complexes and conditions for their existence are determined. Within the pH range of 1.15-9.5, there is NdL monocomplexonate which composition is medium. Calculation of percentage of various anionic H₃L forms depending on pH has shown that HL^2- anion is the basic form over the pH range of 5-9, therefore formation of Nd biscomplexonate is possible. Stability constants of medium mono- and protonated dicomplexes are calculated

[en] 1 : 1 : 1, mixed ligand complex formation of La(III) with ethylenediamine-N,N,N', N'-tetra-acetic acid and certain hydroxy acids such as malic, tartaric, 1-hydroxy-2-naphthoic and 2-hydroxy-3-naphthoic acids has been shown potentiometrically. (author)

[en] Potentiometric equilibrium data are reported for the Hf(IV) chelates of ethylenediaminetetra-acetic acid (EDTA), N-hydroxyethylethylenediaminetri-acetic acid (HEDTA), N-hydroxyethyliminodi-acetic acid (IMDA) at 35⁰C. The formation constants were calculated and the tendencies of these metal chelates to form hydroxo derivatives and olated polynuclear species are outlined. (author)

No abstract available

[en] Stability constants of binary complexes of 1-hydroxy-2-naphthoic and 3-hydroxy-2-naphthoic acids with yttrium(III) and their corresponding ternary complexes involving several polyaminocarboxylic acids have been determined pH-metrically at 25degC and at an ionic strength of 0.1M KNO₃ in 50 per cent aqueous-ethanol medium. The results obtained have been discussed in terms of coulombic interactions and stereochemical factors. (author)

[en] The subject of the patent is a method of separation of high purity rare earth elements and yttrium as well as their oxides. Solution containing rare earth ions (concentration 15-30 g/cm³, pH=3-5) is passed through the column with carboxylic cationite and then the complexing agent (EDTA) is introduced into the column and the eluate is directed to another column with sulfonic cationite. The process is then repeated with EDTA in the sequence of three columns containing different forms of sulfonic cationite. To the eluent leaving the last column concentrated HNO₃ is added for EDTA precipitation. Oxalic acid is added to the residual solution. The precipitated sediments of high purity rare earths and yttrium oxides is then filtrated, washed and dried. 2 tabs