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  • Author or Editor: V. Chakravortty x
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Abstract  

Synergism is observed in the extraction of thorium(IV) by the binary mixture of PC88A and TOPO in the range 0.1–2.5M HNO3 solution. The increase in acidity decreases the synergistic effect. Antagonism is observed when the extraction is carried out in H2SO4 medium.

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Abstract  

Liquid-liquid extraction of uranium(VI) with the binary mixture of quadridentate Schiff base, bis-salicylidene ethylene diamine (H2Salen) (H2A) and neutral donors viz., triphenyl arsine oxide (TPAsO), triphenyl phosphine oxide (TPPO) and tri-n-octyl phosphine oxide (TOPO) has been studied. The extraction order in the equilibrium pH range 2.5 to 5.5 is found to be bis-salicylidene ethylene diamine < bis-salicylidene ethylene diamine + triphenyl phosphine oxide < bis-salicylidene ethylene diamine + tri-n-octyl phosphine oxide < bis-salicylidene ethylene diamine + triphenyl arsine oxide. The composition of the extracted species derived from slope analysis seems to be of the type (UO2A·2TOPO) and (UO2A·2TPPO).

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Abstract  

Studies on solvent extraction of uranium(VI) by a commercially available chelating extractant LIX-54 (a -diketone derivative) (HA) and its mixtures with tri-n-butyl phosphate (TBP) in benzene diluent show quantitative extraction by a mixture of 5% LIX-54 and 5% TBP at pH 4.3. Influence of different proportions of LIX-54 or TBP in the mixtures on the extraction of the same metal ion has been studied. Pronounced synergism has been observed. The composition of the extracted species seems to be [UO2(OH)(A)(HA)(TBP)] as determined from slope analysis. Slopes of the linear plots were computed employing regression analysis and variance in results has been shown.

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Abstract  

The solvent extraction of zirconium from HCl solutions by dipentyl sulphoxide (DPSO), dioctyl sulphoxide (DOSO), tributyl phosphate (TBP), and their mixtures in various solvents has been studied. At a given H+ strength, the extraction coefficient η of the metal increases with an increase in Cl activity whereas it is almost independent of H+ at constant Cl. Under otherwise identical conditions, η increases with an increase in the extractant concentration but is virtually independent of the metal ion concentration over a wide range. The species extracted are ZrCl4·DPSO, ZrCl4·DOSO, and ZrCl4·2TBP. In the case of mixtures, the slope of the log η−log M extractant plot for one component decreases with an increase in the concentration of the second component, the lines crossing at a common point. Extraction is favoured by solvents of low dielectric constant. It is possible to separate zirconium from thorium and uranium by solvent extraction with sulphoxides.

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Abstract  

Extraction studies of uranium(VI) by the binary mixture of PC88A and benzimidazole show an antagonistic behavior in the concentration range 10−5–10−6M of PC88A and 0.005M of benzimidazole. Antagonism is observed due to the deprotonation of PC88A by benzimidazole forming an adduct resulting in the virtual removal of PC88A from the system.

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Abstract  

Liquid-liquid extraction of uranium (VI) from aqueous phosphoric acid solution by triisodecylamine (Alamine 310), tri-n-butyl phosphate (TBP), di-n-pentyl sulfoxide (DPSO) and their mixtures in benzene in the range 1–10M aqueous H3PO4 shows that extraction is maximum (80%) in the higher acidity range 6–8 M. Extraction of this metal ion by bis(2,4,4-trimethylpentyl)phosphinicacid (Cyanex 301) and its mixtures studied in the range 0.2–1.0M aqueous H3PO4 is far from being quantitative. Antagonism in extraction by mixtures of extractants is observed in most of the cases. Extraction of molybdenum(VI) under identical conditions shows that it is quantitative in the lower acidity range upto 2M H3PO4. Separation of uranium(VI) from molybdenum(VI) is feasible by Alamine 310, TBP and DPSO, the order of efficiency being TBP>DPSO>Alamine 310.

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Abstract  

Solvent extraction of thorium/IV/ by a commercially available chelating extractant LIX-54 /a -diketone derivative/ /HA/ and its mixtures with tri-n-butyl phosphate /TBP/, thenoyltrifluoroacetone /HTTA/ and tri-n-octyl phosphineoxide /TOPO/ in benzene as the diluent have been studied. Quantitative extraction of thorium/IV/ by the mixture of 10% LIX-54 and 0.1M TOPO was noticed at pH 2.8. Influence of various concentrations of HTTA and TOPO in their mixtures with LIX-54 on the extraction of the same metal ion has been investigated and pronounced synergism was observed. Slope analyses determination shows the extracted species to be possibly of the type [Th/TTA/2/A/2] in case of extraction by mixtures of HTTA and LIX-54. Slopes of the linear plots were computed employing regression analysis, and variance in results has been shown.

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Abstract  

Extraction of californium/III/ with di-/–2-ethylhexyl/ phosphoric acid /D2EHPA/ in heptane from pyrophosphate media is almost quantitative between pH 4 and 5. From tripolyphosphate media, however, two to three extractions are needed in the pH range of 3–5 to isolate Cf3+ completely. Reextraction experiments show that 1M H2SO4 can back-extract Cf3+ completely while two to three reextractions with 5M HNO3 can only separate californium/III/. Reverse phase partition chromatography experiments were performed to recover 300 g of californium/III/. From slope analysis of the extraction data the composition of the extracted species has been found to be Cf/H2P2O7/A.HA and Cf/H4P3O10/.A2.2HA from pyrophosphate and tripolyphosphate solutions, respectively, where D2EHPA is abbreviated as /HA/2.

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Abstract  

Liquid-liquid extractions of zirconium/IV/, thorium/IV/ and uranium/VI/ with a tetradentate Schiff base, bis/salicylidene/ ethylenediamine /H2Salen/ in benzene as the diluent have been studied. Comparison of such results with those in case of a bidentate Schiff base, N-salicylidene-p-toluidine /HSalTol/ shows that the extraction of UO 2 2+ is significantly improved if H2Salen is used instead of HSalTol2. A single extraction at pH 6.5 with H2Salen removes uranium/VI/. Extraction of all the three metals becomes quantitative at pH 6.5. The extracted species, which have been derived from slope-analyses of extraction results, seem to be of the type [Zr4/OH/12 /HSalen/2]Cl2, [UO2/OH/ /HSalen/] and [Th/OH/3 /HSalen/].

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