Investigation of the use of diphenyl-2-pyridylmethane in benzene as an extractant for palladium from aqueous thiocyanate-nitrate solutions

The extraction of palladium/II/ with diphenyl-2-pyridylmethane /DPPM/ in benzene has been investigated from thiocyanate-nitrate media and optimized. Thiosulphate ions showed strong interference and reduced the extraction below 1%. Separation factors determined for most of the elements were better than 10³. This extraction method affords palladium preconcentration and its separation from Sc/III/, Co/II/, Cu/II/, Zn/II/, Se/IV/, Sr/II/, Ru/III/, Cd/II/, Cs/I/ and Eu/III/. Few possible applications of such separations have been cited.     

Extraction and separation of mercury from toxic elements arsenic,cadmium, antimony and thallium,and other metal ions

Extraction of mercury with 3-methyl-1-phenyl-4-trifluoroacetyl-pyrazolin-5-one /FAP/ in chloroform has been described. Maximum extraction /97.3%/ and a distribution coefficient /D/ of 36.5 have been achieved at pH 8. Among the anions tested, thiourea, thiosulphate and cyanide mask the extraction of mercury. Solution of O. 2M KCN was found most suitable stripping agent for mercury. Decontamination data show that mercury can be separated from toxic elements arsenic, cadmium, antimony and thallium; and from other metal ions i. e. Ga/III/, In/III/, Ge/IV/, Sn/II/, Fe/II/, Ir/IV/ and Pt/IV/. A few separations of analytical and radiochemical importance have been discussed.     

Emulsion membrane systems for preconcentration of uranium

Various double emulsion systems with liquid membranes containing tri-n-octylphosphine oxide /TOPO/, tri-n-butylphosphate /TBP/, KELEX 100^® and di-2-ethylhexylphosphoric acid /DEHPA/, as carriers for uranium/VI/ pertraction, were studied. The conditions were found at which the systems are most efficient, comparing with solvent extraction. The use of DEHPA as a membrane carrier with solutions of H₂SO₄ and H₃PO₄ encapsulated in the membrane was substanfiated.     

Extraction of U/VI/ and U/IV/ with some 1-phenyl-3-methyl-4-acylated-pyrazolone-5 compounds

A series of novel chelating reagents 1-phenyl-3-Methyl-4-p-Nitro-Benzoyl-Pyrazolone-5 /PMNBP/, 1-Phenyl-3-Methyl-4-o-Chlor-Benzoyl-Pyrazolone-5 /PMCBP/, 1-Phenyl-3-Methyl-4-Acyl-Pyrazolone-5 /PMAP/ have been synthesized. The extraction of U/VI/ and U/IV/ from hydrochloric acid in chloroform with these reagents as well as 1-Phenyl-3-Methyl-4-Benzoyl-Pyrazolone-5 /PMBP/ has been studied. The influence of the concentration of the reagents in organic phase, on the distrubtion ratio /D/, has been measured. The coordination of the compounds has been determined with the slope method, and the equilibrium constants k_ex, were measured.     

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.     

Solvent extraction of lanthanoid/III/ with 18-crown-6 from aqueous trichloroacetate solutions to 1,2-dichloroethane

Extraction behaviour of lanthanoid/III/ has been investigated by using 18-crown-6/CR/ as a neutral microcyclic ligand, trichloroacetate/TCA^–/ as an anionic counter ion, and 1,2-dichloroethane as an organic solvent. From the equilibrium studies, the extractable complex such as LnCR³⁺ was found for La/III/, Ce/III/, Pr/III/, Nd/III/, Sm/III/, and Eu/III/ and also the formation of Ln/CR/ ₂ ³⁺ complexes was suggested for Tb/III/, Tm/III/, and Lu/III/. The extractability of lanthanoid/III/ steeply decreased with increase in the atomic number. This order of extractability was a reverse trend compared with that in many other extraction systems reported so far. Very high separation factors especially among light lanthanoid/III/ were observed.     

Thermodynamic studies of complex formation of actinyl ions extracted with TBP from hydrochloric and nitric acids

The changes of the free energy, enthalpy and entropy accompanying the extraction of the U/VI/, Np/VI/ and Pu/VI/ by TBP have been determined by the method of extraction chromatography. The results obtained indicate outer-sphere complexation.     

ESR spectra of radicals at a low-temperature X-radiolysis of phosphates

ESR spectroscopy at 77 K has been used for the investigation of radicals formed in the low-temperature X-radiolysis of tri-n-butylphosphate /TBP/, di-n-butylphosphate /DBP/, di /2-ethylhexyl/phosphoric acid /DEHPA/, tri-p-tolylphosphate /TTP/, di-n-butyl-n-butylphosphonate /DBBPN/. Besides the phosphate radicals also hydrogen atom stabilization in the matrix has been observed. In the presence of oxygen peroxy radicals occur as well. The structure of the radicals and reaction mechanisms are discussed.     

Solvent extraction of Cobalt/II/ from thiocyanate solutions by sulphoxides

The extraction of cobalt/II/ from ammonium thiocyanate solutions by di-n-pentyl sulphoxide /DPSO/, di-n-octyl sulphoxide /DOSO/ and their mixtures in carbon tetrachloride has been studied. The species extracted were found to be Co/SCN/₂. 4S /where S=DOSO or DOSO/. Synergic effects have been observed which are ascribed to the formation of mixed ligand metal complexes. The influence of the metal concentration, temperature and the diluent on the extraction of cobalt/II/has been investigated.     

Conversion of solid amorphous mixed zirconium-titanium phosphates into crystalline from by molten oxalic acid

Solid amorphous mixed zirconium-titanium phosphates, with general formula Zr_xTi_/1–x//HPO₄/₂.n H₂O/ where x=0.1–1, and n=3–5/, are mixed with an excess of solid oxalic acid dihydrate and digested in molten oxalic acid. Then oxalic acid is removed by extraction and the residue washed with dilute /O.OlM/ HCl solution and bidistilled water. As a result of this method, crystalline mixed zirconium-titanium phosphate is formed.     

X- and gamma-radiolysis of phosphate esters. Electron spin resonance study by the spin trap technique

Radicals formed at X- and -radiolysis of glass and liquid tri-n-butylphosphate /TBP/, di-n-butylphosphate /DBP/, di/2-ethylhexyl/phosphoric acid /DEHPA/, tri-p-tolylphosphate /TTP/ and di-n-butyl-n-butyl phopsphonate /DBBPN/ were studied using the technique of spin trap using C-phenyl-N-tert. butylnitrone /PBN/ and 2-methyl-2-nitrosopropane /MNP/ as spin trap agents. When using PBN, nitroxyl radicals generated by the spin trap of hydrogen atoms and labile radicals of phosphates or phosphonate were identified after irradiation in vacuum. Radiation-chemical yield of spin adducts was observed, as well as their thermal stability at 293 K, rate constants and half-time of decay and free activation energy of the decay of spin adducts. Mechanism of generation and decay of nitroxyl radicals is discussed. The spin adducts with MNP have a relatively low stability and superposition of some adducts spectra.     

Solvent extraction separation of In/III/-Tl/III/ and Hg/II/-Cd/II/-Co/II/ with sulphoxides

Solvent extraction studies have been made on some metals: In/III/-Tl/III/ and Hg/II/-Cd/II/-Co/II/, from ammonium thiocyanate solutions by dialkyl sulphoxides. Separation of these metals from one another can be achieved by suitable choice of the extracted conditions. The nature of the extractable metal species has been elucidated.     

Americium removal from nitric acid waste streams

Separations research at the Rocky Flats Plant /RFP/ has found ways to significantly improve americium removal from nitric acid/7M/ waste streams generated by plutonium purification operations. Partial neutralization of the acid waste followed by solid supported liquid membranes /SLM/ are useful in transferring and concentrating americium from nitrate solutions. Specifically, DHDECMP /dihexyl-N, N-diethylcarbamoylmethylphosphonate/ supported on Accurel polypropylene hollow fibers assembled in modular form transfers >95% of the americium from high nitrate /6.9M/, low acid /0.1M/ feeds into 0.25M oxalic acid stripping solution. Maximum permeabilities were observed to be 0.001 cm sec^–1, consistent with typical values for other systems. The feed:strip volume ratio shows an inverse relationship to the fraction of metal ion transferred. Cation exchangers may be used to concentrate americium from the strip solution. Furthermore, OØD/iB/CMPO /or CMPO/ /octylphenyl-N,N-diisobutylcarbamoylmethylphosphine oxide/ has been tested in an extraction chromatography mode. Preliminary results show CMPO to be effective in removing americium if the feed is neutralized to 1.OM acidity and iron/III/ is complexed with 0.20M oxalic acid.     

Determination of131I,134Cs,137Cs in grass and cheese after Chernobyl accident in Austria

Various samples from Styria /grass/ and Salzburg /cheese/ were analyzed for¹³¹I,¹³⁴Cs and¹³⁷Cs concentration during April–July 1986 by -ray spectrometry. The concentrations are reported in nCi kg^–1 wet weight. The concentration values found for¹³¹I 0.2–17.2 nCi kg^–1 /grass/, 0.1–0.5 nCi kg^–1 /cheese/, for¹³⁴Cs 1.1–6.2 nCi kg^–1 /grass/, 0.2–1.3 nCi kg^–1 /cheese/, for¹³⁷Cs 1.6–15.7 nCi kg^–1 /grass/, 0.3–2.2 nCi kg^–1 /cheese/. While radioactivity of¹³¹I,¹³⁴Cs and¹³⁷Cs in cheese samples increases from May to June, it decreases in grass samples from May to July 1986.     

An improved method for the potentiometric determination of plutonium using cerium/IV/ as an oxidant

An improved method for the determination of plutonium in an aliquot using cerium/IV/ as an oxidant is reported. Plutonium is oxidized quantitatively to plutonium/VI/ in nitric acid medium by cerium/IV/, the excess of which is chemically destroyed in a single step by hydrochloric acid. Plutonium/VI/ is then reduced to plutonium/IV/ with a known amount of Fe/II/, the excess of which is back titrated potentiometrically with standard dichromate. Results of analysis of 3–5 mg amounts of plutonium in aliquots containing standard plutonium nitrate solution are reliable within 0.2%. Effect of the presence of some relevant foreign ions has been studied. The application of the method for the analysis of mixtures containing various amounts of uranium and plutonium has been examined.     

Sulphonester podands. A new class of clathrates

The new clathrates based on di- and triethylene glycol ether of phenol sulphonic acid-4 and 1-naphtolsulphonic acid-4 are presented. The four series of p-substituted phenol esters were obtained /Fig. 1/. Generally, only the derivatives of triethylene glycol ether of naphtolsulphonic acid give complexes with benzene or toluene /Tab. I/, but not with smaller molecules of acetonitrile or nitromethane.     

Study on the ternary synergistic extraction of uranium/VI/ by chelating-chelating-neutral extractant

The synergic extraction of uranyl nitrate from chloroform media with 1-phenyl-3-methyl-4-benzoyl-pyrazonole-5 /PMBP/, tributylphosphate /TBP/ and thenoyltrifluorylacetone /TTA/ was studied. It was found that synergic effect occurs during the extraction of uranyl nitrate with the chloroform solution of PMBP-TTA-TBP. The formation of the ternary extracted complex UO₂AA'B was confirmed by the usual slope method. A method was proposed for the calculation of the ternary equilibrium constant which was evaluated to be 1gK₁₁₁=2.65. Also the binary synergic extractions of uranyl nitrate with PMBP-TBP and TTA-TBP were studied. The binary equilibrium constants were found to be 1gK₂₀₁=3.07 and 1gK₀₂₁=1.39, respectively. An attempt has been made to interpret the data mainly on the basis of statistical factor.     

Liquid-liquid extraction of thorium/IV/ with LIX-54 and its mixtures

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.     

Radiation decomposition of metal acetyl acetonates

Studies on the thermal decomposition of the acetyl acetonate complexes of transitional metal ions Cu/II/, Cr/III/, Mn/II/, Co/II/, Fe/III/, Vo/II/, Zn/II/, and Cd/II/ have been performed by thermogravimetric method. Taking the initial decomposition temperature as a measure of thermal stability, the relative order of the thermal stability of these complexes shows the following order: Zn/II/<Cd/II/< VO/II/<Fe/III/<Cr/III/<Cu/II/Co/II/< Mn/II/. The nature of decomposition of Cu/II/ and Cr/III/ complexes is similar, a sigmoid curve exists. In other cases a long linear decomposition follows the sigmoid pattern. The linear decomposition is a function of final decomposition temperature and percentage of decomposition. The kinetics of the decomposition is analyzed according to the Coats-Redfern equation. The results are discussed on the basis of structural and other aspects leading to the decomposition.     

Solvent extraction of99mTc/VII/ with methylene blue into nitrobenzene

The extraction of^99mtechnetium/VII/ with methylene blue into organic solvent has been investigated. Nitrobenzene, which was found to be the most effective extractant for^99mTc/VII/, was used to separate^99mTc/VII/ from other elements. The effect of various parameters on the extraction coefficient value such as effect of pH, time of equilibration, effect of anions and cations on the E value have been evaluated. The stoichiometry of metal to reagent was determined by the slope ratio method and was found to be 11.