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.     

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.     

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 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.     

Speciation of Pu ions by differential pulse polarography

By means of differential pulse polarography, Pu ions of different oxidation states have been investigated in 1M Na₂CO₃ solution. Redox reactions of Pu/III/, Pu/IV/, Pu/V/ and Pu/VI/, which are mostly of irreversible nature, have been observed within the potential range of the dropping mercury electrode /DME/, from 0 to –1.5 V, against a Ag/AgCl/NaCl (3M) reference electrode. Based on the peak potential observed for each reaction, the stability of a given oxidation state in the solution could be ascertained. The redox potential of the Pu/IV/–Pu/III/ pair, which was found to be –1.0 V, indicated that the Pu/IV/ carbonate complex was of high stability. The detection sensitivity of the Pu/IV/ ion was found to be 1×10^–6M.     

Electrochemical oxidation of curium/III/ in potassium carbonate solution

During electrolysis of a²⁴⁸Cm/III/ solution in 2M K₂CO₃ at pH=13 partial oxidation of curium to a higher oxidation state, probably Cm/IV/, was observed. The absorption spectra of Cm/III/ and Cm/IV/ in K₂CO₃ solution were recorded and the molar extinction coefficients of main absorption bands of curium have been evaluated.     

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.     

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.     

Solid state photodecomposition of alkaline earth tris/malonato/ferrates/III/

Solid state photolysis of alkaline earth tris/malonato/ferrates/III/, i.e., M₃[Fe(CH₂C₂O₄)₃]₂.xH₂O /M=Mg, Ca, Sr, Ba/ has been investigated employing Mössbauer, infrared and reflectance spectroscopic techniques. The complexes were irradiated for 400 h using a medium pressure mercury vapour lamp of 250 Watts. Photoreduction led to the formation of M[Fe^II(CH₂C₂O₄)₂(H₂O)₂]. The extent of photoreduction showed the following order: Ca>Sr>Mg>Ba. The results have been compared with those of analogous alkaline earth tris/oxalato/ferrates/III/.     

Radiation induced electron exchange reaction of thallium/I/-thallium/III/ at low sulfate ion concentration in perchloric acid solution

To understand the behaviour of Tl/II/ and the bridging group SO ₄ ^2– in radiation induced electron exchange reactions we have investigated the rate constants and mechanisms of reaction of Tl/II/ with Tl/I/ and Tl/III/ in perchloric acid solutions. The results indicated that Tl/II/ is an intermediate in the -ray induced electron exchange process of T1/I/–T1/III/. Sulfate ions at [SO ₄ ^2– ]>-0.02M serve as bridging groups and play an important role in accelerating the T1/II/–T1/I/ reaction. A cooperative effect was found between hydrogen peroxide and sulfate ion at low sulfate ion concentration, [SO ₄ ^2– ]0.02M in perchloric acid solution.     

A cation-exchange study of stability constants of complexes formed between bismuth/III/ and nitrate or chloride ions

A cation-exchange method was used for determining the stability constants of complexes formed between Bi/III/, present in tracer concentrations /ca. 10^–11M Bi/, and nitrate ion or chloride ion in 1.OM H/ClO₄, NO₃/ or 1.OM H/Cl, ClO₄/ solutions, respectively. The successive formation constants were calculated using the distribution data. The resulting 1g ₁, 1g ₂, and 1g ₃ values were 0.74, 1.22, and 1.54 for 1.OM H/ClO₄, NO₃/ solutions, and 2.36, 3.61, and 4.95 for 1.OM H/Cl, ClO₄/ solutions, respectively.     

Determination of radiocobalt in seawater by successive extractions with the reagents of tris/pyrrolidine dithiocarbamato/bismuth/III/ and ammonium pyrrolidin-dithiocarbamate and back-extraction with bismuth/III/

Method for the isolation and radioactive cobalt /including⁵⁸Co and⁶⁰Co/ from a large volume of seawater and concentration in a small volume of chloroform as tris/pyrrolidine dithiocarbamato/cobalt/III/, Co/PDC/₃, is described. The seawater was extracted first with Bi/PDC/₃ in chloroform for removing parts of foreign metals like Hg, Ag, etc., and then added with ammonium pyrrolidindithiocarbamate, APDC, to complex with Co and possibly other ions and extracted into the organic phase. The final separation of Co from foreign ions in the organic phase was achieved by stripping with a Bi/III/ solution. The overall recovery of radiocobalt activity was found to be about 96%. The established method can be applicable for rapid and reliable determination of radiocobalt in seawater and other aqueous systems for environmental contamination.     

A μSR study on chemical behaviors of positive muons in crystalline tris/acetylacetonato/metal/III/ complexes

Chemical behaviours of positive muons implanted in crystalline tris/acetylacetonato/chromium/III/, iron/III/, and cobalt/III/ were investigated by means of the muon spin relaxation technique. The muon spin relaxation function was exponential in tris/acetylacetonato/iron/III/ and Gaussian in tris/acetylacetonato/cobalt/III/, suggesting that the muon spin relaxation may be ascribed to the interaction between the muon spin and a fluctuating electronic spin in the former and between the muon and a static nuclear spin in the latter. The yield of diamagnetic muon species was found to be nearly unity in these three complexes. Based on the analysis of the relaxation function, it is likely that the positive muon implanted in the cobalt/III/ complex will reside at a distance of about 1.7 A from the cobalt atom.     

Potentiometric determination of uranium in the presence of plutonium in H2SO4 medium

The potentiometric determination of uranium is widely carried out in phosphoric acid medium to suppress the interferences of plutonium by complexation. Owing to the complexity of the recycling plutonium from the phosphate based waste involving manifold stages of separation, a method has been proposed in the present paper which does not use phosphoric acid. Uranium and plutonium are reduced to U/IV/ and Pu/III/ in 1M H₂SO₄ by Ti/III/, and NaNO₂ is chosen to selectively oxidize Pu/III/ and the excess of Ti/III/. The unreacted NaNO₂ is destroyed by sulphamic acid and excess Fe/III/ is added following dilution. The equivalent amount of Fe/II/ thus liberated is titrated against standard K₂Cr₂O₇. R.S.D. obtained for the determination of uranium /1–2 mg/ is 0.3% with plutonium being present upto 4.0 mg.     

Physico-chemical studies on thermal analyses of sodium hexa/carboxylato/ferrates/III/

The thermolysis of sodium hexa/benzoato/ferrate/III/, i. e. Na₃[Fe/C₆H₅COO/₆].4.5H₂O has been investigated at different temperatures in air using Mössbauer, infrared spectroscopic and derivatographic techniques /DTG, DTA, TG/. The thermal decomposition proceeds without the reduction of iron/III/. An increase in particle size of -Fe₂O₃ formed during thermolysis has been observed with increasing temperature. The end product, -NaFeO₂ is formed as a result of the solid state reaction between -Fe₂O₃ and sodium carbonate.     

205T1-NMR and UV-Visible spectroscopic determination of the formation constants of aqueous thallium(I) hydroxo-complexes

The hydrolysis of T1(I) has been studied at 25°C using²⁰⁵T1-NMR spectroscopy and UV-Vis spectrophotometry in aqueous solutions with ionic strengths maintained by NaC10₄ at 2, 4, 6, and 8M. The formation constant and the spectral characteristics for the hydroxo complex, T10Hℴ have been determined. At high hydroxide ion concentrations there is clear evidence from the UV-Vis data for the formation of a T1(OH)₂-species. The spectrum and an estimated formation constant for this second hydroxo complex are also reported.     

Base hydrolysis of halobis/8-quinolinolato/ oxotechnetium/V/ complexes

Reaction mechanism of base hydrolysis of halobis/8-quinolinolato/oxotechnetium (V) /TcOX (ox)₂ X=Cl and Br/ was investigated by means of solvent extraction and spectrophotometric methods. Furthermore, distribution coefficients of tris/acetylacetonato/technetium/III/, dichlorobis/8-quinolinolato/technetium/IV/ and TcOX/ox/₂ between chloroform and aqueous solutions were determined. In an alkaline solution, TcOX/ox/₂ decomposed to pertechnetate as a final product. On the basis of the established base hydrolysis, the respective rate constants were determined.     

Sulphoxide complexes of ruthenium

Summary Compounds of the type RuL_4–nX_2+n where L = dimethyl sulphoxide (DMSO), tetramethylene sulphoxide (TMSO) and X = Cl, Br or I for n = 0 and L = di-n-propyl sulphoxide (n-Pr₂SO) and di-n-butyl sulphoxide (n-Bu₂SO) X = Cl or Br for n = 1 and also Ru(DMSO)₆Br₃ have been prepared and studied. The important i.r. bands of all compounds together with their electronic spectra and the thermograms of some of them are discussed. In order to interpret the i.r. data, the corresponding deuteriated (DMSO-d₆) analogues have also been prepared. In the majority of the compounds of the type RuL₄X₂ the sulphoxide ligands are bonded through the sulphur atom; in a few cases, bonding through both S- and O-donor sites has been found. A mixed type of bonding is also observed in Ru(DMSO)₆Br₃ and in RuL₃X₃.     

Structure Re‐determination and Superconductivity Observation of Bulk 1T MoS2

2H MoS₂ has been intensively studied because of its layer‐dependent electronic structures and novel physical properties. Though the metastable 1T MoS₂ with a [MoS₆] octahedron was observed over the microscopic area, the true crystal structure of 1T phase has not been strictly determined. Moreover, the true physical properties have not been demonstrated from experiments owing to the challenge for the preparation of pure 1T MoS₂ crystals. 1T MoS₂ single crystals were successfully synthesized and the crystal structure of 1T MoS₂ re‐determined from single‐crystal X‐ray diffraction. 1T MoS₂ crystallizes in the space group P m1 with a cell of a=b=3.190(3) Å and c=5.945(6) Å. The individual MoS₂ layer consists of MoS₆ octahedra sharing edges with each other. More surprisingly, the bulk 1T MoS₂ crystals undergo a superconducting transition of T_c=4 K, which is the first observation of superconductivity in pure 1T MoS₂ phase.     

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.