Extraction of actinides and fission products from salt solutions using polyethylene glycols (PEGs)

The extraction behavior of several metal ions viz., Am³⁺, Eu³⁺, UO₂ ²⁺, Th⁴⁺, Sr²⁺ and Cs⁺ was investigated from sulphate medium employing phosphotungstic acid (PTA) and polyethylene glycol (PEG). The influence of various parameters such as pH, PTA concentration, PEG concentration and salt concentration was studied. The order of extraction followed the trend: Am³⁺>Eu³⁺>>Th⁴⁺>UO₂ ²⁺>Sr²⁺>Cs⁺ which deviate significantly from the reported order with conventional solvents. The relatively poor extraction of UO₂ ²⁺, Sr²⁺ and Cs⁺ was ascribed to their lack of interaction with the phosphotungstate anion. The separation behaviour of Am³⁺ vis-a-vis Eu³⁺ was also investigated under different experimental conditions.     

Trennungen von Kationen in Titanhexacyanoferrat(II)-S?ulen

Zusammenfassung Die Trennung der Ionenpaare Rb⁺/Cs⁺, K⁺/Rb⁺, K⁺/Cs⁺, Na⁺/K⁺, Li⁺/Na⁺ mit Salzsäure oder Ammoniumchloridlösung als Elutionsmittel gelingt quantitativ oder nahezu quantitativ mit Hilfe von Titanhexacyanoferrat(II)-säulen. Die Cäsiumionen können nicht eluiert werden. Ebenso gelingt die Trennung der lonenpaare Sr²⁺/Ba²⁺, Ca²⁺/Ba²⁺, Ba²⁺/Cs⁺ und Sr²⁺/Cs⁺ quantitativ oder nahezu quantitativ. Auch eine partielle Trennung der Seltenen Erden ist möglich; Yttrium ist leichter eluierbar als die Lanthanide.

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Summary The quantitative or nearly quantitative separation of the ion pairs Rb⁺/Cs⁺, K⁺/Rb⁺, k⁺/Cs⁺, Na⁺/K⁺ and Li⁺/Na⁺ can be achieved with hydrochloric acid or ammonium chloride solutions as eluents by means of columns of titanium hexacyanoferrate(II). The elution of the Cs⁺ ions is not possible. In the same way the quantitative or nearly quantitative separation of the ion pairs Sr²⁺/Ba²⁺, Ca²⁺/Ba²⁺, Ba²⁺/Cs⁺ and Sr²⁺/Cs⁺ can be achieved. Also a partial separation of the rare-earth elements is possible; yttrium is more easily eluted than the lanthanides.

     

Preconcentration and recovery of uranium and thorium from Indian monazite sand by using a modified fly ash bed

Adsorption of uranium, as UO₂ ²⁺, and thorium, as Th⁴⁺, has been studied using a modified fly ash bed. Effects of pH and various ions like La³⁺, Fe³⁺, Ce⁴⁺, SiO₃ ^2- etc., have been examined. Synthetic mixtures of UO₂ ²⁺ and Th⁴⁺ in different concentrations were passed through the bed and eluted separately with various selective reagents viz. ammonium carbonate, sodium carbonate and acetic acid-sodium hydroxide buffer. Separations of these elements at ppm level are shown to be very effective. The separation of uranium and thorium in the presence of lanthanides in monazite sand has been studied successfully. In the analysis of monazite sand, the oxalate precipitation has been avoided. The method is simple and of very low cost. The modified fly ash bed can also be used to remove uranium from contaminated water.     

Lattice polarization effects in electrochromic switching in WO3−x films studied by pulse-nanogravimetric technique

The interactions of various types of cations with the tungsten trioxide lattice have been investigated to evaluate possible intercalation of these cations and the occurrence of lattice polarization leading to the near-surface structural lattice damage. The interactions of cations, such as the large monovalent cations (K⁺, Et₄N⁺, CtMe₃N⁺ cations), transition metal dications (Ni²⁺), heavy metal ions (Cd²⁺), and representative lanthanides (La³⁺) and actinides (Th⁴⁺), in competition with intercalation of H⁺ ions have been investigated using pulse-nanogravimetric technique. The effects of these cations in electrochromic processes of WO₃ proceeding during cathodic reduction have been assessed. For all of the metal ions studied, a large increase in the apparent mass uptake (up to eightfold) in comparison to pure H⁺ ion ingress was observed upon the film coloration induced by a cathodic potential pulse. The experiments indicate that the apparent mass gains, although large, are insufficient to confirm predominant contribution of metal ions in the ion transport along the channels in WO₃ lattice. The lower decoloration rate in the case of Ni²⁺ ions, in comparison to H⁺ and other transition metal cations (Cd²⁺), has been attributed to a slow dissociation of Ni²⁺ ions from lattice-bound oxygen atoms. For et₄N⁺ cation, which is too large to enter channels in WO₃, a dissociative reduction of the WO₃ and severe lattice damage was observed. Among the metal ions investigated, only K⁺ ions have been found to cause a dissociative reduction of WO₃ and near-surface lattice damage. Strong lattice polarization effects and irreversible binding have been found for La³⁺ and Th⁴⁺ cations.     

Adsorption of tracer cations,and the separation of carrier-free95Nb from95Zr,XU1 from U and45Ca from46Sc on titanium phosphate column

Titanium phosphate as ion exchanger for column operation has been prepared by mixing TiCl₄ and H₃PO₄ in suitable proportion. The ratio of titanium: phosphate was obtained to be 1:2.02. The uptake of Na⁺, K⁺, Rb⁺, Cs⁺, Ag⁺, Ca²⁺, Sr²⁺, Ba²⁺, Pb²⁺, Sc³⁺, Co³⁺, Y³⁺, Tb³⁺, Zr⁴⁺ and Th⁴⁺ cations at very small concentrations has been studied on this exchanger. The data indicated that the different cations are adsorbed in the exchanger by different mechanisms. Radiochemical separations of carrier free⁹⁵Nb from⁹⁵Zr, UX₁ from U and⁴⁵Ca from⁴⁶Sc have been achieved by adopting very simple chemical procedures through a column of titanium phosphate. The -spectrum of the separated⁹⁵Nb, UX₁ and⁴⁶Sc showed that the products are of high radionuclidic purity. The individual separation procedures took less than 20 min and the yields are quantitative.     

Interaction of actinide ions with [NaP5W30O110]14- and [P2W18O62]6-

Stability constants (log b₁₀₁) of Th⁴⁺, UO₂ ²⁺, NpO₂ ⁺ and Am³⁺ with [NaP₅W₃₀O₁₁₀]^14- were determined by solvent extraction (m = 0.1M NaCl) and found to be 6.18±0.07, 3.80±0.06, 2.98±0.04, and 5.85±0.05, respectively. The order of stability constants: Th⁴⁺>Am³⁺>UO₂ ²⁺>NpO₂ ⁺ is due to electrostatic repulsion between the actinyl oxygens and oxygens on the polyoxometalate surface. The order of stability constants for metal complexes with [P₂W₁₈O₆₂]^6- is Th⁴⁺>UO₂ ²⁺>Eu³⁺>NpO₂ ⁺ because the steric repulsion between actinyl oxygens and oxygens on polyoxometalate are less important. Enthalpies of complexation were measured by calorimetric titration of Th⁴⁺, UO₂ ²⁺, Nd³⁺ with [NaP₅W₃₀O₁₁₀]^14- and [P₂W₁₈O₆₂]^6-. The results indicate that the conformation and charge distribution of the microscopic surface structures are important factors in the formation of pseudocolloids.     

Anion-exchange separation of thorium and protactinium from uranium matrix

Summary The distribution behaviour of Th⁴⁺, Pa⁵⁺, and UO₂ ²⁺ ions between the anion-exchanger Amberlite IRA-400 and acetic acid-hydrochloric acid mixtures, has been investigated. It was found that the general behaviour of Th⁴⁺ ions is similar to that of UO₂ ²⁺ ions though the latter are much more highly adsorbed by the resin than Th⁴⁺. Protactinium exhibited a different behaviour from both Th⁴⁺ and UO₂ ²⁺ ions. The separation factors were calculated, and a Chromatographic procedure for sequential isolation of each element was developed.

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Zusammenfassung Das Verteilungsverhalten von Th⁴⁺, Pa⁵⁺ und UO₂ ²⁺ zwischen dem Anionenaustauscher Amberlit IRA-400 und Gemischen aus Essigsäure und Salzsäure wurde untersucht. Das allgemeine Verhalten von Th⁴⁺ ist ähnlich dem von Uranylionen, wenngleich letztere von dem Harz viel stärker adsorbiert werden als Th⁴⁺. Protactinium zeigt ein abweichendes Verhalten im Vergleich zu Th⁴⁺ und UO₂ ²⁺. Die Trennfaktoren wurden berechnet und ein chromatographisches Verfahren zur Isolierung der angeführten Ionen entwickelt.

     

A new solvent system for the separation of Th4+, UO 2 2+ and Zr4+ in the presence of common anions by thin-layer chromatography

Summary A TLC method has been developed for separating Th⁴⁺, UO₂ ²⁺ and Zr⁴⁺ in the presence of some common anions using a dimethylamine/acetone/formic acid mobile phase. Capacity factors, separation factors and resolution for the separation of Th⁴⁺ from UO₂ ²⁺ have been evaluated. The effect of the pH of the sample on R_F values of Th⁴⁺, UO₂ ²⁺, Ni²⁺ and Cu²⁺ has also been examined.     

Preparation and ion-exchange properties of zirconium tungstoarsenate

A new inorganic ion-exchanger, zirconium tugnstoarsenate, has been synthesized which has been characterized by chemical analysis, thermogravimetry, X-ray and infrared spectroscopy. The ion exchanger has been found to be stable in acids and neutral salt solutions. The K_d values for 30 metal ions have been determined at pH 3–4 which show that the exchanger has high affinity for UO ₂ ²⁺ , ZrO²⁺, Cs⁺ and Tl⁺ ions. The variation of K_d for a number of metal ions as a function of concentration of nitric acid and ammonium nitrate has been investigated to elucidate the probable exchange mechanism and to work out conditions for elution. Some binary separations, viz. Sr²⁺−Cs⁺, Sr²⁺−Rb⁺, Sr²⁺−Y³⁺, Fe³⁺−Al³⁺, Fe³⁺−Zn²⁺ and Zn²⁺−Hg²⁺ in trace amounts have been carried out on the column of the exchanger which demonstrate the utility of the exchanger in radionalytical and analytical chemistry.     

Highly Selective Recovery of Lanthanides by Using a Layered Vanadate with Acid and Radiation Resistance

It is of vital importance to capture lanthanides (nuclear fission products) from waste solutions for radionuclide remediation owing to their hazards. The effective separation of lanthanides are achieved by an acid/base‐stable and radiation‐resistant vanadate, namely, [Me₂NH₂]V₃O₇ ( 1 ). It exhibits high adsorption capacities for lanthanides (q_m^Eu=161.4 mg g^?1; q_m^Sm=139.2 mg g^?1). And high adsorption capacities are maintained over a pH range of 2.0–6.9 (q_m^Eu=75.1 mg g^?1 at low pH of 2.5). It displays high selectivity for Eu³⁺ (simulant of An³⁺) against a large excess of interfering ions. It can efficiently separate Eu³⁺ and Cs⁺ (or Sr²⁺) with the highest separation factor SF_Eu/Cs of 156 (SF_Eu/Sr of 134) to date. The adsorption mechanism is revealed by calculations and XPS, EXAFS, Raman, and elemental analyses. These merits combined with facile synthesis and convenient elution makes the title vanadate a promising lanthanide scavenger for environmental remediation.     

Direkt-potentiometrische Konzentrationsbestimmungen mit ionensensitiven Elektroden unter Verwendung komplexierender Hilfsreaktionen

Zusammenfassung Die Grundlagen der direkt-potentiometrischen Konzentrationsbestimmung von Anionen und Kationen werden beschrieben, für die keine ionensensitiven Elektroden bekannt sind. Es wird die Konzentrationsabnahme eines Hilfsions gemessen, das mit dem analytisch zu bestimmenden Ion einen stabilen Komplex bildet.Ausführliche Angaben werden zur Bestimmung von Al³⁺ mit F^– als Hilfsion und von Ni²⁺ mit CN^– als Hilfsion gemacht. Auf die prinzipiellen Möglichkeiten einer Bestimmung von Fe²⁺, Fe³⁺, Au⁺, Hg²⁺, Th⁴⁺, Zr⁴⁺, UO₂ ²⁺, SCN^– und S₂O₃ ^2– wird eingegangen.

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Direct-potentiometric determinations with ion-sensitive electrodes using complexing auxiliary reactions

The basic principles of the direct-potentiometric determination of several cations and anions are discussed, for which no ion-sensitive electrode is available. The decrease in concentration of an auxiliary ion is measured which forms stable complexes with the ion to be determined. Detailed information is given on the determination of Al³⁺ with F^– as auxiliary ion and of Ni²⁺ with CN^– as auxiliary ion. An outlook is presented on the possible determinations of Fe²⁺, Fe³⁺, Au⁺, Hg²⁺, Th⁴⁺, Zr⁴⁺, UO₂ ²⁺, SCN^– and S₂O₃ ^2–.

     

Microdetermination of uranium (VI)

Summary A new method has been evolved for the separation and estimation of UO₂ ²⁺ from Cu²⁺, Zn²⁺, Ag⁺, Pb²⁺, Ga³⁺, In³⁺, Tl³⁺, La³⁺, Ti⁴⁺, Zr⁴⁺ and Th⁴⁺ with the sodium salt of benzilic acid as precipitating and chelating agent andn-butanol as solvent for solvent extraction. All these cations except UO₂ ²⁺ are precipitated by benzilic acid; UO₂ ²⁺ forms a deep yellow complex extractable byn-butanol. The uranium can be determined in the organic phase spectrophotometrically at 430 nm. The pH range over which the separation can be carried out is 2.6–4.0. Few anions and cations interfere.

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Zusammenfassung Eine neue Methode der Trennung und Bestimmung von UO₂ ²⁺ neben Cu²⁺, Zn²⁺, Ag⁺, Pb²⁺, Ga³⁺, In³⁺, Tl²⁺, La³⁺, Ti⁴⁺, Zr⁴⁺ und Th⁴⁺ wurde ausgearbeitet. Das Natriumsalz der Benzilsäure dient als Färbungs- und Komplexbildungsmittel und n-Butanol zur Extraktion. Alle angeführten Kationen mit Ausnahme von UO₂ ²⁺ werden von Benzilsäure gefällt; UO^{2 2+} bildet einen tiefgelben, mit n-Butanol extrahierbaren Komplex und kann in der organischen Phase spektrophotometrisch bei 430 nm bestimmt werden. Die Trennung kann bei pH 2,6 bis 4,0 durchgeführt werden. Nur wenige Anionen und Kationen stören.

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Résumé On développe une nouvelle méthode pour la séparation et l'évaluation de UO₂ ²⁺ dans Cu²⁺, Zn²⁺, Ag⁺, Pb²⁺, Ga³⁺, In³⁺, Tl³⁺, La³⁺, Ti⁴⁺, Zr⁴⁺ et Th⁴⁺, par le sel de sodium de l'acide benzilique comme agent précipitant et chélatant et le N-butanol comme solvant pour l'extraction par solvant. Tous ces cations, sauf UO₂ ²⁺, précipitent par l'acide benzilique; UO₂ ²⁺ forme un complexe jaune intense que l'on peut extraire par le N-butanol. On peut doser l'uranium en phase organique par spectrophotométrie à 430 nm. La séparation peut s'effectuer dans le domaine de pH de 2,6 à 4,0. Peu d'anions et de cations interfèrent.

     

Ion exchangers containing phosphorus in their functional group

Summary Uranium or thorium separations from a number of various ions were studied by means of cation exchangers containing phosphorus in their functional group. These ion exchangers adsorb selectively only UO₂ ²⁺ or Th⁴⁺ ions from the mixture studied in a medium of >0.4 N nitric or hydrochloric acid. Several di- and trivalent cations are not sorbed under these conditions. In the absence of UO₂ ²⁺ and Th⁴⁺ ions, Me²⁺ may be more easily separated quantitatively from Me³⁺ in 0.2 N nitric or hydrochloric acid than with cation exchangers containing the -SO₃H group.

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Zusammenfassung Die quantitative Trennung von UO₂ ²⁺ oder Th⁴⁺ von einer Reihe anderer Ionen wurde mit Hilfe phosphorhaltiger Kationenaustauscher untersucht. Diese Ionenaustauscher sorbieren selektiv nur UO₂ ²⁺ oder Th⁴⁺-Ionen aus einem Medium von >0,4 N HNO₃ oder HCl. Eine Reihe verschiedener zwei- und dreiwertiger Kationen wird unter diesen Bedingungen nicht sortiert. Bei Abwesenheit von UO₂ ²⁺- und Th⁴⁺-Ionen kann man Me²⁺ in 0,2 N HNO₃- oder HCl-Lösung quantitativ von Me³⁺ trennen, und zwar leichter als mit -SO₃H-haltigen Austauschern.

     

Role of stannic phosphate in the uptake of cations. Separation of zirconium from thorium and cadmium from indium at tracer concentrations

The uptake of Na⁺, K⁺, Rb⁺, Cs⁺, Ag⁺, Ca²⁺, Cu²⁺, Sr²⁺, Cd²⁺, Ba²⁺, Pb²⁺, Sc³⁺, Co³⁺, Y³⁺, Sb³⁺, Tb³⁺, Zr⁴⁺ and Th⁴⁺ cations at very small concentrations has been studied over a column of stannic phosphate. The exchanger was prepared by mixing H₃PO₄, NaCl and SnCl₄ in suitable proportions and the ratio of PSn, in the product was obtained to be 1.96. Radiochemical separations of carrier free⁹⁵Zr from²³⁴Th and^115mIn, from¹¹⁵Cd have been carried out by adopting a simple chemical procedure over a column of stannic phosphate. The -spectrum analysis showed that the separated products are of high radionuclidic purity. The separation procedures took less than half an hour with quantitative yield.     

Synthesis, characterization and analytical application of a new inorganic cation exchanger—Titanium(IV) molybdophosphate

A novel polyoxometalate-cation exchanger, titanium(IV) molybdophosphate (TMP) has been synthesized under varying conditions. The material was characterized by X-ray diffraction, infrared spectroscopy, inductively coupled plasma and thermogravimetry techniques. Its stability was investigated in water, dilute acids, alkaline solutions, and high temperature up to 750 °C. Ion-exchange capacity and distribution coefficients (K_d) for twenty-nine radionuclides and metal ions have been determined. It was found that the TMP has high affinity for Cs⁺, Sr²⁺, UO₂²⁺, Ba²⁺, Pb²⁺, Tl⁺, Zn²⁺, Rb²⁺ and Zr⁴⁺ ions. The results of binary separation of metal ions showed that TMP can be potentially useful for analytical applications.     

A new ecomaterial zirconyl molybdopyrophosphate for the removal of 137Cs and 90Sr from HLLW

A new ecomaterial, zirconyl molybdopyrophosphate (ZMPP), was prepared by a coprecipitation method. The removal of Cs⁺ and Sr²⁺ ions from simulated strong acid HLLW using the ion exchange process on ZMPP had been investigated. It showed that there are more than 90% Cs⁺ and Sr²⁺ removed from the simulated HLLW on ZMPP despite the presence of other metal ions, such as Na⁺, Al³⁺, Fe³⁺, etc. in excess. Then ZMPP may likely be a selective ion exchanger for the removal of ¹³⁷Cs and ⁹⁰Sr directly from strong acid HLLW.     

Direct titrimetric microdetermination of uranium

Summary Direct titrimetric method for the estimation of uranium(VI) in the range of 0.7 to 76 mg is performed by decomposing and oxidising the complex, {U(VI)O₂ · U(V)O₂ · Fe(CN)₆}, with ceric sulphate. The mixed valency state in the above mentioned complex has been confirmed by magnetic measurements, the isolated complex being paramagnetic. Na⁺, K⁺, Cs⁺, Ca²⁺, Sr²⁺, Mg²⁺, Be²⁺, Pd²⁺, La³⁺, Ir³⁺, Ru³⁺, and Te⁴⁺ do not interfere but Ag⁺, Tl⁺, Cu²⁺, Ba²⁺, CO²⁺, Ni²⁺, Zn²⁺, Pb²⁺, Hg²⁺, Sn²⁺, Bi³⁺, Au³⁺, Rh³⁺, Sb³⁺, In³⁺, Ti³⁺, Th⁴⁺, Zr⁴⁺, Pt⁴⁺, V⁵⁺, Se⁶⁺, MO⁶⁺, and Os⁸⁺ do.

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Zusammenfassung Die Bestimmung von Uran(VI) in der Größenordnung von 0,7 bis 76 mg erfolgt durch Zersetzung und Oxydation des Komplexes U(VI)O₂ · U(V)O₂ · · Fe(CN)₆ mit Cer(IV) sulfat. Die zweierlei Wertigkeitsstufen in diesem paramagnetischen Komplex wurden durch magnetische Messungen bestätigt. Na⁺, K⁺, Cs⁺, Ca²⁺, Sr²⁺, Mg²⁺, Be²⁺, Pd²⁺, La³⁺, Ir³⁺, Ru³⁺, and Te⁴⁺ stören nicht; hingegen stören Ag⁺, Tl⁺, Cu²⁺,Ba ²⁺, CO²⁺, Ni²⁺, Zn²⁺, Pb²⁺, Hg²⁺, Sn²⁺, Bi³⁺, Au³⁺, Rh³⁺, Sb³⁺, In³⁺, Ti³⁺, Th⁴⁺, Zr⁴⁺, Pt⁴⁺, V⁵⁺, Se⁶⁺, MO⁶⁺, and Os⁸⁺.

     

Condensation reaction in the bandpass reaction cell improves sensitivity for uranium,thorium, neodymium and praseodymium measurements

Condensation reactions in the bandpass reaction cell or dynamic reaction cell (DRC) were used for the determination of actinides and lanthanides such as uranium, thorium, neodymium and praseodymium. These elements react with oxygen reagent gas in the dynamic reaction cell of the ELAN DRC II instrument to give mono- and/or dioxo cationic species (UO₂⁺, ThO⁺, NdO⁺ and PrO⁺, respectively). Increasing the oxygen flow rate in the dynamic reaction cell leads to the rapid decrease of the singly charged metal ions accompanied by the fast increase in the intensity of the oxide ion. This phenomenon is used to improve considerably the sensitivity of ICP-MS instruments equipped with a dynamic reaction cell for actinides and lanthanides. Estimated detection limits (EDL) obtained in this work for uranium, thorium, neodymium-144 and praseodymium are 0.022, 1.0, 0.045, and 0.10 ng L^–1, respectively. The detection limit for uranium measured in the standard (vented) mode of an ELAN DRC II was found to be 0.22 ng L^–1, which is an order of magnitude higher compared to the pressurized mode.     

Selectivity for Cs and Sr in Nb-substituted titanosilicate with sitinakite topology

The 25% niobium substituted crystalline titanosilicate with the composition Na_1.5Nb_0.5Ti_1.5O₃SiO₄·2H₂O (Nb-TS) was synthesized under hydrothermal conditions. Its selectivity for radioactive ¹³⁷Cs and ⁸⁹Sr was compared with the TS, Na₂Ti₂O₃SiO₄·2H₂O, having sitinakite topology. The Nb-TS shows significantly higher uptake value for ¹³⁷Cs but lower for ⁸⁹Sr than the TS. To investigate the origin of selectivity, the ion exchanged Cs⁺ and Sr²⁺ forms with the composition, Cs_xNaH_yNb_0.5Ti_1.5O₃SiO₄·zH₂O (x=0.1, 0.2 and 0.3, x+y=0.5 and z=1-2) and Sr_0.2Na_0.6H_0.5Nb_0.5Ti_1.5O₃SiO₄·H₂O, respectively, were structurally characterized from the X-ray powder diffraction data using the Rietveld refinement technique. Simultaneously the kinetics of ¹³⁷Cs and ⁸⁹Sr uptake was investigated for the Nb^V free and doped samples. While the Cs⁺ and Sr²⁺ exchanged form of Nb-TS and the Cs⁺ exchanged form of TS retain the symmetry of the parent compound, the Sr²⁺ exchanged form of TS undergoes a symmetry change. The differences in the uptake of Cs⁺ and Sr²⁺ result from the different coordination environments of cesium and strontium in the eight-ring channel, that result from various hydration sites in the tunnel. The origin of selectivity appears to arise from the higher coordination number of cesium or strontium. Other effects due to Nb^V substitution are reflected in the increase of both, the a- and c-dimensions and thus the unit cell volume, and the population of water vs. Na⁺ in the channel to charge-balance the Nb⁵⁺↔Ti⁴⁺ substitution.     

Liquid-liquid extraction of uranium(VI) and thorium(IV) by two open-chain crown ethers with terminal quinolyl groups in chloroform

Two open-chain crown ethers 2,2'-(ethylenedioxy)bis[(8-quinolyloxymethyl)benzene], (L1), and 2,2'-(ethylenedioxy)bis[(8-quinaldyloxymethyl)benzene], (L2) have been prepared and characterized by using elemental analysis, IR spectra, ¹H NMR spectra and positive-ion FAB mass spectra. The extraction of UO₂ ²⁺ and Th⁴⁺ by both open-chain crown ethers, L1 and L2 in chloroform as a diluent was studied at 25 °C. Extraction distribution ratios (D) of UO₂ ²⁺ and Th⁴⁺ were investigated as a function of pH, lithium picrate concentration, and extractant concentration. Based on the expertimental results, it was found that 1 : 1 complexes were formed involving either UO₂ ²⁺ or Th⁴⁺ with L1, and Th⁴⁺ with L2. The extractability of L1 for Th⁴⁺ is significantly higher than that for UO₂ ²⁺, the extractabilities of L1 and L2 for Th⁴⁺ being almost identical. L1 and L2 used here are not feasible for industry because of their relatively low extractabilities for Th⁴⁺ at pH<2.0 and for UO₂ ²⁺ at the extraction conditions used in this work.