The use of trioctylphosphine oxide for solvent extraction recovery and purification of transplutonium elements

Extraction of trivalent curium, berkelium, californium, einsteinium, and europium with trioctylphosphine oxide (TOPO) from nitric acid solutions as well as extraction of curium and cerium from lactic acid solutions containing DTPA depending on aluminium nitrate concentration have been studied. The distribution of cobalt, nickel, chromium, iron, aluminium, titanium, zirconium, and niobium ions has been studied and coefficients of berkelium purification from the elements studied have been determined under the conditions of extraction-chromatographic recovery of berkelium. The influence of weighed amounts of the same impurities on the yield of berkelium in its extraction-chromatographic separation has been studied. Some examples of the practical application of the extraction-chromatographic techniques using TOPO are given.     

Extraction of californium/III/ from aqueous pyrophosphate and tripolyphosphate solutions with D2EHPA

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.     

Chemical treatment of US Department of Energy high level and low level waste to obtain a pure radiochemical fraction for determination of californium alpha-decay content

We have developed a chemical separation technique that allows the radiochemical determination of the californium -decay content in Department of Energy (DOE) high level wastes from the Hanford and Savannah River sites. The chemical separation technique uses a series of column extraction chromatography steps that use Eichrom Industries' lanthanide and actinide +3 oxidation state selective Ln-resin^® and the transuranic selective +4 oxidation state TRU-resin^® to obtain intermediate product phases in dilute nitric acid. The technique has been demonstrated on three types of authentic DOE high and low level waste samples. We obtain discrimination from Pu -activity by a factor of over 200 and from ²⁴⁴Cm -activity by a factor approaching 1700. Californium recoveries are measured by addition of a ²⁴⁹Cf spike and are in the range of 50% to 90% in the synthetic samples and are in the range of 1.4% to 48% for the authentic DOE waste samples.     

A simple and effective method for the purification of californium from other elements

The distribution coefficients of californium and other elements between an anion exchange resin and alcohol solutions of nitric acid of different concentrations have been determined. An effective method is suggested for the purification of californium from other elements which are slightly adsorbed when Cf is concentrated on an anion exchanger from 0.5–1.0N solutions of nitric acid containing 95–90% alcohol; Cf is subsequently eluted with a 0.5N HNO₃ solution in 85% CH₃OH and simultaneously separated from the elements which are strongly adsorbed on the anion exchange resin. Under the chosen conditions the coefficients of californium purification were determined for a number of elements; the values are 5.4·10²–1.8·10³ for Al, Ca, Fe and ∼10³–10⁵ for Am, Pm, Nd, Ce, Pb, Bi and Na, for one cycle.     

Extractive separation of group IVB elements: analysis of alloy samples

A method is proposed for the extraction and mutual separation of quadrivalent titanium, zirconium and hafnium from hydrochloric acid using triphenylphosphine oxide dissolved in toluene as an extractant. The optimum conditions for the extraction and separation have been evaluated from critical study of acid concentration, extractant concentration, period of equilibration and effect of diluent. The effect of foreign ions on the extraction and determination is also discussed. The probable composition of the extracted species has been deduced from logD-logC plots. The method affords mutual separation of titanium, zirconium and hafnium and is applicable to the analysis of alloy samples.     

Electrochemical oxidation of californium in carbonae solutions

The electrolysis of trivalent californium, terbium and praseodimium in 2M K₂CO₃ solutions at pH 13.2 results in a partial oxidation of the trivalent ions to a higher oxidation state. Absorption spectra of Cf/III/ in 1M HCLO₄ and in 2M K₂O₃ and that of oxidized californium in carbonate solution have been recorded. Incomplete oxidation is accounted to a reducing species generated at high anode potentials.     

P-507回流萃取法富集镥的研究——Ⅰ.P-507萃取分离镱镥混合稀土的性能

本文研究了2-乙基己基膦酸单2-乙基己基酯(P-507)在盐酸和硝酸体系中萃取镱镥混合稀土的性能。说明P-507在硝酸体系中的萃取分离系数较其在盐酸体系中高,而在盐酸体系中有更高的反萃效率。与二(2-乙基己基)磷酸(P-204)相比,P-507具有萃取酸度低、易反萃和不易乳化的优点。我们还确定了回流萃取法分离镥镱的基本参数,表明P-507是一种新型的分离重稀土的良好萃取剂。     

Analysis of ochratoxins from buffered rumen fluid by reversed-phase high-performance liquid chromatography (HPLC)

Summary An efficient procedure for the extraction and analysis of ochratoxins A, B, C and α from buffered rumen fluid has been developed. The samples have been cleaned up byliquid-liquid extraction and the separation of chratoxins was by isocratic elution on a 5μm C₁₈ ODS-column which 0.083 M phosphoric acid/acetonitrile/isopropanol (55/35/10).     

Extraction of americium(VI) by a neutral phosphonate ligand

Recently the use of the more unusual hexavalent oxidation state of americium has been receiving increased attention for the purpose of developing an efficient Am/Cm or Am/lanthanide separation system. We have already demonstrated the feasibility of performing this separation with 30% TBP in dodecane, and are now looking at different extractants to increase Am(VI) distribution ratios. Following on from this the extraction of bismuth oxidized americium from nitric acid solutions by dibutyl butyl phosphonate has been studied. The results of this study indicate that increasing the basicity of the extractant molecule has significantly improved the extraction efficiency.     

Problems of the speciation of chromium in soil samples

Different separation/detection methods (ion exchange, organic extraction, spectrophotometry) and four extraction media have been compared for the speciation of chromium. Due to the pH dependence of these methods only the spectrophotometric method using the diphenylcarbazide reaction has proved suitable for speciation analyses. If nitric acid is used for the initial extraction stage, problems are often encountered with the other method during subsequent speciation analysis. The reasons for this are discussed.     

Use of complexones for the extraction separation of rare earth and transplutonium elements with amines

The extraction distribution and separation of rare earth elements and americium from the concentrated lithium nitrate solution with solutions of tertiary amines in organic solvents has been studied as a function of the composition and structure of complexones of the polyaminepolyacetic acid series by a radioactive tracer method. It has been found that diethylenetriaminepentaacetic acid is suitable for the separation of REE from americium(III). The apparent stability constants for the lanthanide complexes with EDTA and DTPA in concentrated litium nitrate solutions have been obtained by extraction, pH-metric titration and solubility. Using these constants, the optimum conditions of separation have been found and the separation factors of REE calculated. The calculated and experimental values are in good agreement. The optimum conditions for the separation of americium(III) from REE in a wide range of lanthanide and complexone concentrations (10⁻¹–10⁻⁶ M) have been determined.     

Chemical separation and ICP-AES determination of 22 metallic elements in U and Pu matrices using cyanex-923 extractant and studies on stripping of U and Pu

Comprehensive studies have been carried out on the extraction behavior of uranium and plutonium matrices using cyanex-923 extractant. The near total extraction of U/Pu and quantitative separation of 22 metallic elements at trace levels has been established using inductively coupled plasma-atomic emission spectrometry (ICP-AES). The studies carried out on back extraction of U/Pu from organic phase have established the near total recovery of these matrices into the aqueous phase using 1 M Na(2)CO(3) and saturated oxalic acid, respectively.     

Instrumental neutron activation determination of gold in mineral raw materials using a californium neutron source

A facility using a californium neutron source and a method for the neutron activation analysis of gold were developed. The sensitivity of the determination is 0.1 g/t. The sources of random and systematic errors have been studied. It has been concluded that in prospection and evaluation of gold ore deposits, the traditional test tube analysis for gold may be replaced with the developed method.     

Solvent extraction separation of rubidium with a crown ether for neutron activation analysis in rock samples

The extraction behavior of rubidium with a crown ether has been studied and methods for the separation and determination of rubidium have been developed. Rubidium was separated with tetraphenylborate from sample solution, and then quantitatively extracted into nitrobenzene by 18-crown-6 from 0.05 mol/l picric acid (pH 6) and back-extracted by 6 mol/l hydrochloric acid. Rubidium was determined by the neutron activation method in rock samples.     

Resolution concept for separation of curium from californium by ion-exchange chromatography

Different factors affecting separation of the tervalent actinides curium and californium by ion-exchange chromatography are discussed in the light of the resolution factor. The fact that resolution is inversely proportional to resin particle diameter and directly proportional to column length has been confirmed experimentally. The effects influencing resolution due to changes in flow-rate of the mobile phase used are dependent on resin particle diameter. Changes in temperature affect a number of variables influencing resolution.     

Liquid-liquid solvent extraction of rare earths from chloride medium with sec-nonylphenoxy acetic acid and its mixtures with neutral organophosphorus extractants

In the present study, sec-nonylphenoxy acetic acid (CA100) and its mixtures with four neutral organophosphorus extractants, tri-butyl-phosphate (TBP), 2-ethylhexyl phosphonic acid di-2-ethyl ester (DEHEHP), Cyanex923, and Cyanex925 have been applied to the extraction of rare earths. Results show that all the four mixing systems do not have evident synergistic effects on the extraction of rare earths. The different extraction effects have been considered to the separation of rare earths. The four mixtures may be applied to the separation of yttrium from some certain lanthanoids at proper mole fractions of CA100.     

Extractive separation and spectrophotometric determination of palladium and platinum with dithizone in the presence of stannous chloride

The conditions [acid used, presence of chloride and tin(II)] for the extractive separation and spectrophotometric determination of palladium and platinum as the dithizonates Pd(HDz)(2) and Pt(HDz)(2) have been examined. In the absence of stannous chloride platinum does not undergo extraction. Conditions for the separation and determination of these metals in the presence of mercury, gold and copper, which are also extracted with dithizone into carbon tetrachloride or chloroform under the conditions suitable for palladium (1M sulphuric acid/0.1M hydrochloric acid), have been defined. The mercury and gold dithizonates are formed quickly and can be removed before the palladium and platinum compounds have had time to form. They can be decomposed with iodide. Copper dithizonate is decomposed by reduction with tin(II). The proposed procedure has been applied to the determination of palladium in technical platinum metal.     

仲辛基苯氧基乙酸从稀土中萃取分离钪及其机理

首次研究了一种新型萃取剂仲辛基苯氧基乙酸 (CA 12 )萃取钪的性能及其机理。通过研究平衡水相酸度、萃取剂浓度和温度对萃取平衡的影响 ,用斜率法和等摩尔系列法确定了CA 12萃取钪的机理 ,并求得了CA 12萃取钪的热力学函数 ,计算了平衡反应的浓度平衡常数及钪同其它稀土离子的分离系数 ,指出CA 12是一种从稀土 中分离钪的优良萃取剂     

Selective extraction and separation of cadmium using tri-n-octylamine

The extraction of cadmium by tri-n-octylamine in benzene and cyclohexane from a mixture of sulphuric acid and potassium bromide has been investigated in detail. The optimum conditions for the extraction and back-extraction of cadmium have been found. The procedure for the concentration of cadmium is described and the separation of cadmium in the presence of more than 30 metals including fission products is presented.     

Solvent extraction separation of T1/I/ from T1/III/ with sulphoxides

A method for the separation of microgram quantities of T1/I/ and T1/III/ from hydrochloric acid solutions has been developed. T1/III/ was extracted as HTlCl₄ into benzene by di-n-pentyl sulphoxide /DPSO/ and di-n-octyl sulphoxide /DOSO/. Conditions for the effective extraction of T1/III/, free from T1/I/, have been worked out.