Thermal behavior and other properties of Pr(III), Sm(III), Eu(III), Gd(III), Tb(III) complexes with 4,4′-bipyridine and trichloroacetates

A novel mixed-ligand complexes with empirical formulae: Ln(4-bpy)_1.5(CCl₃COO)₃·nH₂O (where Ln(III) = Pr, Sm, Eu, Gd, Tb; n = 1 for Pr, Sm, Eu and n = 3 for Gd, Tb; 4-bpy = 4,4′-bipyridine) were prepared and characterized by chemical, elemental analysis and IR spectroscopy. Conductivity studies (in methanol, dimethylformamide and dimethylsulfoxide) were also described. All complexes are crystalline. The way of metal–ligand coordination was discussed. The thermal properties of complexes in the solid state were studied under non-isothermal conditions in air atmosphere. During heating the complexes decompose via intermediate products to the oxides: Pr₆O₁₁, Ln₂O₃ (for Sm, Eu, Gd) and Tb₄O₇. TG-MS system was used to analyze principal volatile thermal decomposition and fragmentation products evolved during pyrolysis of Pr(III) and Sm(III) compounds in air.     

Extraction of U(VI), Th(IV), and La(III) from acidic streams and geological samples using AXAD-16–POPDE polymer

A new chromatographic extraction method has been developed using Amberlite XAD-16 (AXAD-16) resin chemically modified with (3-hydroxyphosphinoyl-2-oxo-propyl)phosphonic acid dibenzyl ester (POPDE). The chemically modified polymer was characterized by ¹³C CPMAS and ³¹P solid-state NMR, Fourier Transform–NIR–FIR–Raman spectroscopy, CHNPS elemental analysis, and thermogravimetric analysis. Extraction studies performed for U(VI), Th(IV), and La(III) showed good distribution ratio (D) values of approximately 10³, even under high acidities (1–4 M). Various physiochemical parameters that influence the quantitative metal ion extraction were optimized by static and dynamic methods. Data obtained from kinetic studies revealed that a time duration of 10 min was sufficient to achieve complete metal ion extraction. Maximum metal sorption capacity values under optimum pH conditions were found to be 1.38, 1.33, and 0.75 mmol g^–1 for U(VI), Th(IV), and La(III), respectively. Interference studies performed in the presence of concentrated diverse ions and electrolyte species showed quantitative analyte recovery with lower limits of analyte detection being 10 and 20 ng cm^–3 for U(VI) and both Th(IV) and La(III), respectively. Sample breakthrough studies performed on the extraction column showed an enrichment factor value of 330 for U(VI) and 270 for Th(IV) and La(III), respectively. Analyte desorption was effective using 15 cm³ of 1 M (NH₄)₂CO₃ with >99.8% analyte recovery. The analytical applicability of the developed resin was tested with synthetic mixtures mimicking nuclear spent fuels, seawater compositions and real water and geological samples. The rsd values of the data obtained were within 5.2%, thereby reflecting the reliability of the developed method.     

Extraction behavior of uranium(VI), plutonium(IV), zirconium(IV), ruthenium(III) and europium(III) with γ-pre-irradiated solutions of N,N′-methylbutyl substituted amides in n-dodecane

The extraction of plutonium(IV), uranium(VI), zirconium(IV), europium(III) and ruthenium(III) with -pre-irradiated n-dodecane solutions of methylbutyl substituted hexanamide (MBHA), octanamide (MBOA) and decanamide (MBDA) from 3.5M HNO₃ has been studied as a function of absorbed dose up to 184×10⁴ Gray. The distribution ratios (K_d) of uranium(VI) decreased gradually up to a dose of 50×10⁴ Gray and became almost constant thereafter, while ruthenium(III) and europium(III) were not extracted in the entire dose range studied. The K_d values of Pu(IV) decreased gradually up to 10×10⁴ Gray, for MBOA, and 30×10⁴ Gray for MBHA and MBDA and then increased up to a dose of 72×10⁴ Gray, indicating the synergistic effect of radiolytic products at higher doses. The extraction of zirconium(IV) was found to increase gradually up to 72×10⁴ Gray. However, the steep fall in K_d values of plutonium(IV), zirconium(IV) beyond a dose of 72×10⁴ Gray was atrributed to third phase formation. The radiolytic degradation of amides was monitored by quantitative IR spectroscopy and was found to follow the order MBOA>MBDA>MBHA at 184×10⁴ Gray having the amines and carboxylic acids as the main radiolytic products.     

The precipitation of some actinide element complex ions by using hexammine cobalt(III) cation—VI The precipitation of Np(IV), (V) and (VI) sulfate complex ions with hexammine cobalt(III) cation

Precipitation behaviors of Np(IV), (V) and (VI) in sulfuric acid and ammonium sulfate solutions with hexammine cobalt(III) ion have been studied. The optimum conditions of precipitating Np as crystalline compounds are 0.4 M H₂SO₄ and 0.06 M [Co(NH₃)₆]Cl₃ for Np(IV), larger than 0.5 M (NH₄)₂SO₄ and 0.03 M [Co(NH₃)₆]Cl₃ for Np(V), and the higher the concentrations the better for Np(VI). Np(IV) is completely removed from ammonium sulfate solution.Composition of the Np(IV) compound from the sulfuric acid solution is [Co(NH₃)₆]₂[Np(SO₄)₅]·nH₂O. And composition of the Np(V) compounds is possibly [Co(NH₃)₆][NpO₂(SO₄)₂]·α[Co(NH₃)₆]₂(SO₄)₃·nH₂O (α = 2.20−0.32). Solubilities of the Np(IV), (V) and (VI) compounds in water are found to be 4.9 mgNp/l, 520 mgNp/l, and 250 mgNp/l, respectively.     

Counter-current extraction and separation of U(VI) from a mixture of U(VI)–Th(IV)–Y(III) using tris-2-ethyl hexyl phosphate (TEHP)

Evaluation of tris-2-ethyl hexyl phosphate (TEHP) for counter-current extraction and separation of U(VI) from a mixture of U(VI)–Th(IV)–Y(III) from nitric acid medium was carried out under wide experimental conditions. Batch extraction studies were carried out to investigate the effect of nitric acid concentration in feed solution, U(VI)/Th(IV) ratio and extractant concentration and the results were compared with established solvent such as tri-n-butyl phosphate (TBP) for separation of U(VI) from nitric acid medium. McCabe–Thiele diagrams for extraction as well as stripping of U(VI) were constructed under simulated conditions. Based on batch experiments, six stage counter-current extraction studies were conducted under various TEHP concentration and it was observed that 0.1 M TEHP/n-paraffin was most suitable for selective recovery of U(VI) from a mixture of U(VI)–Th(IV). An optimized condition, 0.1 M TEHP/n-paraffin, 2 M HNO₃ in feed and six number of stages was evaluated for selective extraction and stripping of U(VI) from a solution containing mixture of U(VI)–Th(IV)–Y(III) in nitric acid medium. The U(VI) in strip solution was precipitated using 30 % H₂O₂ at pH ~3. Average particle size of the final precipitate was found to be ~33 μm.     

Extraction of actinides by long-chain amines—I: Extraction of Np(IV), Np(V), Np(VI), Pu(VI) and U(VI) by TLA and Aliquat-336

The extraction of Np(IV) into tricaprylmethyl ammonium nitrate (Aliquat-336) and Np(V), Np(VI), Pu(VI) and U(VI) into TLA and Aliquat-336 from nitric acid medium was investigated. The absorption spectra of Aliquat-336 extracts containing Np(IV), Pu(IV), Np(VI) and Pu(VI) were obtained to know the species of these ions present in the amine.     

Synthesis and luminescence properties of Eu(III)-doped silica nanorods based on the sol–gel process

Uniform Eu³⁺-doped SiO₂ nanorods were synthesized through a simple sol–gel method using cetyltrimethylammonium bromide (CTAB) as surfactant template and tetraethylorthosilicate as silicon source. X-ray diffraction, energy-dispersive X-ray spectroscopy, Fourier transform infrared spectrum, scanning electron microscope (SEM), transmission electron microscopy, and photoluminescence spectra were employed to characterize the products in detail. The nanorods have good uniformity and their diameters and lengths are in the range of 200–300 and 500–700 nm through the SEM images, respectively. The formation of the nanorods was studied by taking SEM images after different aging time. The experimental results indicate that CTAB plays a crucial role in the formation of the silica nanorods. The luminescence of Eu³⁺-doped SiO₂ nanorods is dominated by red-emission around 612 nm due to intra-atomic 4f → 4f (⁵D₀ → ⁷F₂₎ transition of Eu³⁺ ions. Furthermore, the effect of doping concentrations of Eu³⁺ ions on the luminescence was investigated.     

Transport behaviour of the lanthanide 152Eu(III), 153Gd(III) and 170Tm(III) and transplutonium element 254Es(III), 244Cm(III), 241Am(III), 249Cf(III) and 249Bk(III) ions in aqueous solutions at 298 K

Ionic self-diffusion coefficients (D) for trivalent radiotracers, lanthanide and actinide ions have been determined in concentrated aqueous solutions of supporting electrolytes of Gd(NO₃)₃–HNO₃ or Nd(ClO₃)₄–HClO₄ up to 1.5 mol L^?1 at 298.15 K and pH 2.50 by the open-end capillary method. The data obtained in large range of concentrations, allow to derive the limiting value D°, the validity of the Onsager limiting law and a more extended law. This study contributes to demonstrate similarities in transport and structure properties between 4f and 5f trivalent ions explained by a similar electronic configuration, ionic radius and hydration number. An empirical equation is suggested for predicting ionic hydration number with a good precision.     

Complexation of Eu(III), Am(III) and Cm(III) with Dicarboxylates: Thermodynamics and Structural Aspects of the Binary and Ternary Complexes

The complexation of Eu(III), Am(III) and Cm(III) with dicarboxylate anions with O, N or S donor groups was measured in I=6.60 mol⋅kg⁻¹ (NaClO₄) at temperatures of 0–60 °C by potentiometry and solvent extraction. The complexation thermodynamics of these complexes show that their stability is due to highly favorable complexation entropies because the complexation enthalpies are endothermic. Luminescence studies with Eu(III) and Cm(III) were used to measure the hydration numbers of the complexes. NMR spectra of ¹H and ¹³C were used to determine the binding modes of La(III) with the ligands. The formation of 1:1:1 ternary complexes of M(EDTA)⁻ with the dicarboxylate ligands was studied to determine changes in coordination of the metal cation with formation of the ternary species. The complexation of ternary complexes changes from bidentate to monodentate as the chain length between the binding sites of the dicarboxylates increases from 1 (malonate) to 4 (adipate). DFT computations were used to confirm the structural aspects of the interaction of these complexes.     

Competitive sorption of Cu(II) and Eu(III) ions on olive-cake carbon in aqueous solutions—a potentiometric study

The competitive sorption of Cu(II) and Eu(III) ions from aqueous solutions by olive-cake carbon, has been investigated by potentiometry at pH 6, I=0.1 M NaClO₄, 25°C and under normal atmospheric conditions. Evaluation of the experimental data supports the formation of inner-sphere surface complexes and results in the calculation of the formation constant of the surface complexes ((=S–O)₂Cu), which is found to amount log β _Cu=5.3±0.3. Addition of competing Eu(III) ions in the aqueous system leads to replacement of the Cu(II) by the competitor metal ion. Evaluation of the potentiometric data obtained from competition experiments indicates an ion-exchange mechanism. The formation constant of the Eu(III) species sorbed on olive cake carbon is found to be log β _Eu=5.1±0.5. Comparison of the complex formation constants of the olive-cake carbon with the corresponding complex formation constants for of olive cake and humic acid with the two metal ions, indicates that the same type of active sites is responsible for the metal ion complexation on the surface of the different types natural organic matter (e.g. olive-cake carbon, olive-cake and humic acid).     

Extraction chromatographic study of aluminium(III) and mutual separation of aluminium(III), gallium(III), indium(III) and thallium(III) with N-n-octylaniline

A selective method has been developed for extraction chromatographic studies of aluminium(III) and its separation from several metal ions with a chromatographic column containing N-n-octylaniline (liquid anion exchanger) coated on silanized silica gel as a stationary phase. The aluminium(III) was quantitatively extracted with the 0.065 mol/L N-n-octylaninine from 0.013 to 0.05 mol/L sodium succinate at a flow rate of 1.0 mL/min. The extracted metal ion has been recovered by eluting with 25.0 mL of 0.05 mol/L hydrochloric acid and estimated spectrophotometrically with aurintricarboxylic acid. The effects of the acid concentration, the reagent concentration, the flow rate and the eluting agents have been investigated. The log-log plots of distribution coefficient (KdAl(III)) versus N-n-octylaniline concentrationin 0.005 and 0.007 mol/L sodium succinate gave theslopes 0.5 and 0.7 respectively and showed theprobable composition of theextracted species was 1:1 (metal to amine ratio) and the nature of extracted species is [RR''NH2+ Al succinate2-] org. .The extraction of aluminium(III) was carried out in the presence of various ions to ascertain the tolerance limit of individual ions. Aluminium(III) has been separated from multicomponent mixtures, pharmaceutical samples and synthetic mixtures corresponding to alloys. A scheme for mutual separation of aluminium(III), indium(III), gallium(III) and thallium(III) has been developed by using suitable masking agents. The method is fast, accurate and precise.     

Die Bestimmung von Uran(VI) neben Uran(IV), Eisen(II, III), Vanadium (III, IV, V), Molybd?n (IV, VI) und Kupfer (II)

Ohne Zusammenfassung     

Extraction of U(VI), Th(IV) and some fission products from nitric acid medium by sulfoxides and effect of γ-irradiation on the extraction

The extracting abilities for thorium, uranium and some fission products by five sulfoxides are given. The results show that di(2-ethylhexyl) sulfoxide (DEHSO) is not only completely miscible with kerosene, but also superior to tri-n-butyl phosphate in some properties. The extraction behavior of uranium, thorium and some fission products such as zirconium, niobium and ruthenium from aqueous nitric acid with DEHSO in kerosene has been studied over a wide range of conditions. DEHSO extracted uranium and fission products better than TBP under all conditions and is similar to TBP in extraction of thorium. A study of extraction mechanism indicates that U and Th are extracted as disolvates, whereas HNO₃ is extracted as monosolvate. Extraction of the two actinides decreases with increasing temperature, indicating the extraction to be exothermic. Preliminary studies show that -ray irradiated DEHSO extracts Zr and Nb to a smaller extent than irradiated TBP in the range of 10⁴–10⁷ rad.     

Complexation of Sc(III), Ga(III), In(III) and Ln(III) with Eriochrome Red B

Cyclic linear-sweep voltammetry was used to study the complexation of Sc(III), Ga(III), In(III) and Ln(III) with eriochrome red B (ERB). It was established that all metal ions investigated form complex compounds with azodye having a mole ratio, M(III):ERB = 1:2. The hydroxo forms of M(III) ions, which take part in interaction with ERB, were determined by the Nazarenko method. The stability constants for the formation of these chelates are nearly the same. It was shown that the reduction of the ligand in the complex does not only depend on the peculiarities of complexation, but the processes occurring in pre-electrode layer also influence it.     

Extraction of U(VI) and Th(IV) from nitric acid solutions with N,N,N′,N′-tetrahexylsuccinylamide

The results of monitoring of⁸⁵Kr volume activity in ground-level air of Prague over the period 1989–1995 are summariyed. Seasonal dependence with a maximum in late spring and summer months and a gradual increase of⁸⁵Kr concentration in the atmosphere were observed. Linear approximation of long-term trend in the period 1983–1995 gives the growth rate of 35 mBq·m^–3 per year. Exponential approximation provides an inter-year growth by 3.7% The measured values were compared to the prognosis of⁸⁵Kr contamination development of the atmosphere from the early 1980s. They were found to be near to the low estimate of the assumed development.     

Complexes of N-phenyl-N′-2-furanthiocarbohydrazide with oxovanadium(IV), manganese(III), iron(III), cobalt(II), nickel(II), copper(II) and zinc(II)

A new ligand, N-phenyl-N -2-furanthiocarbohydrazide (HPhfth), and its complexes with VO^IV, Mn^III, Fe^III, Co^II, Ni^II, Cu^II and Zn^II have been prepared and characterized by elemental analyses, magnetic susceptibility measurements, i.r., n.m.r., u.v.–vis., mass and FAB mass spectral data. The room temperature e.s.r. spectra of the VO^IV, Fe^III and Cu^II complexes yield <g> values characteristic of square pyramidal VO^IV, octahedral Fe^III and square planar Cu^II, respectively. The Ni^II and Cu^II complexes semiconduct, but the Zn^II complex is an insulator at room temperature. However, the conductivity increases as the temperature increases from 303–383 K, with a band gap of 0.21–1.01 eV. HPhfth and its soluble complexes have been screened against several bacteria and fungi.     

Simultaneous determination of gold(III), palladium(II), and platinum(IV) with N-phenyl-N′-(sodium p-aminobenzenesulfonate)thiourea

The preparation and characteristics of a new water-soluble reagent, N-phenyl- N'-(sodium p-aminobenzenesulfonate)thiourea (PPT) are described. In the presence of cetyltrimethylammonium bromide (CTMAB) PPT reacts with Au(III), Pd(II), and Pt(IV) to form colored complexes with absorption maxima at 317 nm, 306.1 nm, 778.4 nm, respectively. Optimum conditions for color development were studied. The reagent was used for the simultaneous determination of Au(III), Pd(II), and Pt(IV); Amberlyst A-26 macropore anion-exchange resin was used as a means of rapid separation. The method was applied to the determination of Au(III), Pd(II), and Pt(IV) in catalyst materials and anode mud with satisfactory results.     

Preconcentration and separation of trace Pd(II) and Pt(IV) with silica gel bonded by aminopropyl-benzoylazo-4-(2-pyridyl-azo)-resorcinol

This paper reports a simple and highly selective method for preconcentrating and separating of trace Pd(II) and Pt(IV) with silica gel bonded by aminopropyl-benzoylazo-4-(2-pyridy-lazo)-resorcinol (ABPR-SG). ABPR-SG is stable in solution from 6 mol/L HCl to pH 7.0 and in common organic solvents. The maximum adsorptive capacity of Pd(n) on ABPR-SG is 362 μmol/g. After preconcentration and separation by using ABPR-SG column, Pd(II) and Pt(IV) of μg/L level in artificial water samples can be measured reliably by common spedrophotometry. The maximum concentration factors of Pd(II) and Pt(IV) on ABPR-SG column are 143 and 125 respectively. The chromatographic column packed with ABPR-SG can be reused. The method is simple and efficient.     

Synthesis,thermal study and some properties of Gd(III), Tb(III), Dy(III) and Er(III) complexes with 4,4′-bipyridine and dibromoacetates

Journal of Thermal Analysis and Calorimetry - New complexes with formulae: Ln(4-bpy)(CBr2HCOO)3·3H2O (where Ln(III)&nbsp;=&nbsp;Gd, Tb, Dy) and Er(4-bpy)1.5(CBr2HCOO)3·3H2O, were...     

Extraction of U(VI), Th(IV) and some fission products from nitric acid by n,n-disubstituted amides and effect of γ-ray irradiation on the extraction

In this work, ten disubstituted amides have been synthesized and the extracting ability for U and Th fission products (mainly Zr, Nb and Ru) and the tendency of third phase formation have been studied. From the preliminary studies, two disubstituted amides, N-octylcaprolactam (OCLA) and N-(2-ethyl) hexylcaprolactam (EHCLA) were chosen for further studies. All studies were compared with those obtained by using TBP under exactly the same conditions. The dependence of aqueous nitric acid concentration, extractant concentration, temperature, -ray irradiation on extraction of Th, U and some fission products were studied. Back extraction of Th and U from organic phases and third phase formation were also studied. The studies of the reaction mechanism indicate that Th and U are extracted as disolvates, whereas HNO₃ is extracted as monosolvate. Extraction distribution of Th and U decrease with increase of temperature, indicating the extraction reaction to be exothermic. Preliminary studies show that OCLA and EHCLA have better -irradiation stabilities compared with TBP.