Adsorption and Separation of <Superscript>152+154</Superscript>Eu(III) and <Superscript>60</Superscript>Co(II) Using Cerium(IV) Tungstate

Samples of cerium(IV) tungstate (CeW) inorganic ion exchanger were synthesized using different Ce(IV) salts: (NH₄)₂Ce(NO₃)₆·2H₂O, (NH₄)₄Ce(SO₄)₄·2H₂O, and Ce(SO₄)₂·4H₂O. The samples were characterized using FT-IR and X-ray diffraction. The adsorption behavior of ^152+154Eu(III) and ⁶⁰Co(II) on CeW was studied under batch and dynamic conditions. Factors influencing the adsorption kinetics were examined. Loading and elution behavior of both ions was studied using different eluents. Complete separation of Eu(III) and Co(II) (^152+154Eu and ⁶⁰Co tracers) was achieved using small columns packed with CeW.     

Synthesis,structural characterization and photophysical properties of highly photoluminescent crystals of Eu(III), Tb(III) and Dy(III) with 2,5-thiophenedicarboxylate

Lanthanide compounds of general formula [Ln₂(2,5-tdc)₃(dmf)₂(H₂O)₂]·2dmf·H₂O (Ln = Eu(III) (1), Tb(III) (2), Gd(III) (3) and Dy(III) (4), dmf = N,N′-dimethylformamide and 2,5-tdc²⁻ = 2,5-thiophedicarboxylate anion) were synthesized and characterized by elemental analysis, X-ray powder diffraction patterns, thermogravimetric analysis and infrared spectroscopy. Phosphorescence data of Gd(III) complex showed that the triplet states (T₁) of 2,5-tdc²⁻ ligand have higher energy than the main emitting states of Eu(III), Tb(III) and Dy(III), indicating that 2,5-tdc²⁻ ligand can act as intramolecular energy donor for these metal ions. An energy level diagram was used to establish the most relevant channels involved in the ligand-to-metal energy transfer. The high value of experimental intensity parameter Ω₂ for the Eu(III) complex indicate that the europium ion is in a highly polarizable chemical environment. The emission quantum efficiency (η) of the ⁵D₀ emitting level of Eu(III) was also determined. The complexes act as possible light conversion molecular devices (LCMDs).     

Improvement of lasing properties of europium (III) complexes by increase of emission quantum yield

Deuterated Eu(III) complexes of tris-(hexafluoroacetylacetonato)europium(III) dehydrates (Eu(hfa-H)₃(H₂O)₂), tris-(hexafluoroacetylacetonato)europium(III) bis(triphenylphospine oxide) (Eu(hfa-H)₃(TPPO)₂), tris(hexafluoroacetylacetonato) europium(III) 1,1′-biphenyl-2,2′-diylbis (diphenylphosphine oxide) (Eu(hfa-H)₃(BIPHEPO)) were prepared by the exchange reaction via keto-enol tautomerism of the Eu(III) complexes with CD₃OD. The emission quantum yields of the deuterated Eu(III) complexes were higher than those of corresponding non-deuterated Eu(III) complexes. The lasing properties of Eu(III) complexes in polymer thin film were measured by photo-pumping of Nd: YAG laser (355 nm). Percentages of ASE components in whole emission were increased by deuteration of the Eu(III) complexes.     

Effect of O2, H2O2, and HNO2 on the stability of Np(III–VII) in aqueous solutions

Published data on reactions of Np ions with O₂, H₂O₂, HNO₂, and HNO₃ in solutions of various compositions in a wide pH range are considered. O₂ oxidizes Np(III) in acid solution and Np(IV) and Np(V) in alkaline solutions. H₂O₂ exhibits dual behavior. In weakly acidic solutions, it converts Np(III) and (IV) to Np(V), in 0.75?C1 M NaHCO₃ it oxidizes Np(V) to Np(VI), whereas in dilute HClO₄ and HNO₃ and in carbonate and alkali solutions it reduces Np(VI), and in alkali solutions it reduces Np(VII). The first step of reduction in most cases is the formation of the Np(VI) peroxide complex, and the next step is the intramolecular charge transfer. In concentrated HNO₃ solutions, H₂O₂ converts Np(V) to Np(IV) and Np(VI) and then reduces Np(VI). Some radiation-, photo-, and sonochemical reactions occur via formation of excimers, i.e., of dimers arising from excited and unexcited Np ions. The excimer decomposes into two ions with higher and lower oxidation states. In reduction reactions, the excimer eliminates H₂O₂ (in addition to the H₂O₂ arising as primary product of water radiolysis). In HNO₃ solutions, oxidation of Np ions occurs only in the presence of HNO₂ arising as reaction product or upon radiolysis, photolysis, or sonolysis. The active species are NO ₂ ^? , NO₂, and NO⁺ present in equilibrium with HNO₂.     

Mechanisms of Pu(VII) reduction in aqueous alkaline solutions in the presence of catalysts

Published data on the Pu(VII) stability in alkaline media suggest that one-electron oxidation of OH^? ion or H₂O with Pu(VII) ions is thermodynamically impossible. The more probable pathway of Pu(VII) reduction is formation of a dimer from thermodynamically excited and nonexcited Pu(VII) ions, followed by decomposition of the dimer into two Pu(VI) ions and H₂O₂ molecule, which reacts with Pu(VII) and Pu(VI). The released energy is spent for Pu(VII) excitation. In the presence of difficultly soluble hydroxides of Fe(III), Co(III), and other d elements, and also of Pt and PbO₂, hydroxides of elements in higher oxidation states appear at the surface of colloidal particles and electrode materials under the action of Pu(VII). The neighboring OH groups dimerize and are eliminated in the form of H₂O₂.     

Synthesis,XPS and fluorescence properties of Eu3+ complex with polydimethylsiloxane

Eu(III)-containing polymer complex was synthesized, in which polydimethylsiloxane was used as a polymer ligand. The complex was characterized by ultraviolet-visual, infrared, X-ray photoelectron and fluorescence spectroscopy. The results exhibit that the metal Eu(III) ion is directly bonded to oxygen atoms in polymer chain of PDMS and formed the complex of Eu(III)-containing polymer. On the other hand, the blue light at 455 nm in the complex under UV excitation at room temperature, in which the emission peak is assigned to the ⁵D₂→⁷F₀ transition of Eu(III) ion, was enhanced. Therefore, there is an efficient intermolecular energy transferred from the polymer to the rare earth ions. Meanwhile, the fluorescence intensity change of Eu(III)-PDMS displays typical concentration quenching mechanism.     

Preparation, photoluminescence and thermal stability of sodium tris(pyridine dicarboxylato) europate(III) complex incorporated into silica matrix

Silica-based composite materials incorporated with sodium tris(pyridine dicarboxylato) europate(III), SiO₂ : Na₃Eu(DPA)₃, where H₂DPA is 2,6-pyridine dicarboxylic acid, were prepared by a sol-gel method. Photoluminescent properties of SiO₂ : Na₃Eu(DPA)₃ composite were studied after heat treatment between room temperature and 600 °C. The strong red emission of SiO₂ : Na₃Eu(DPA)₃ was intensified by heat-treatment under appropriate conditions. The thermal stability of Na₃Eu(DPA)₃·9H₂O and its silica-based composite was examined. The results demonstrate that SiO₂ : Na₃Eu(DPA)₃ composite material possesses very good thermal stability with intense visible fluorescence, and may be applied as a potential luminescent material.     

Effect of Mn substitution on the oxidation/adsorption abilities of iron(III) oxyhydroxides

In this study, divalent manganese ions [Mn(II)] were substituted a part of divalent iron ions [Fe(II)] present in Fe oxyhydroxides to prepare novel composites (Mn@Feox). The composites were prepared by (1) simultaneous hydrolysis of Fe(II) and Mn(II), and (2) rapid oxidation with H₂O₂. The resulting Mn@Feox prepared with different molar ratios of Fe and Mn was characterized and evaluated for their abilities to adsorb arsenic species [As(III) and As(V)] in aqueous solution. X-ray diffraction and field emission transmission electron microscope analyses revealed Mn@Feox has a δ-(Fe_1?x, Mn_x)OOH-like structure with their mineralogical properties resembling those of feroxyhyte (δ-FeOOH). The increase in Mn substitution in Mn@Feox enhanced the oxidative ability to oxidize As(III) to As(V), but it decreased the adsorption capacity for both arsenic species. The optimal Mn/Fe molar ratio that could endow oxidation and magnetic capabilities to the composite without significantly compromising As adsorption capability was determined to be 0.1 (0.1Mn@Feox). The adsorption of As(III) on 0.1Mn@Feox was weakly influenced by pH change while As(V) adsorption showed high dependence on pH, achieving nearly complete removal at pH?<?5.7 but gradual decrease at pH?>?5.7. The adsorption kinetics and isotherms of As(III) and As(V) showed good conformity to pseudo-second-order kinetics model and Freundlich model, respectively.     

Selective extraction and detection of noble metal based on ionic liquid immobilized silica gel surface using ICP-OES

In this study, an efficiently employed ionic liquid combined with commercially available silica gel (SG–ClPrNTf₂) was developed for selective detection of gold(III) by use of inductively coupled plasma–optical emission spectrometry (ICP-OES). The selectivity of SG–ClPrNTf₂ was evaluated towards seven metal ions, including Y(III), Mn(II), Zr(IV), Pb(II), Mg(II), Pd(II) and Au(III). Based on pH study and distribution coefficient values, the SG–ClPrNTf₂ phase was found to be the most selective towards Au(III) at pH 2 as compared to other metal ions. The adsorption isotherm of Au(III) on the SG–ClPrNTf₂ phase followed the Langmuir model with adsorption capacity of 59.48 mg g^?1, which was highly in agreement with experimental data of adsorption isotherm study. The kinetics study indicated that Au(III) adsorption kinetics data were well fit with the pseudo-second-order kinetic model on the basis of correlation coefficient fitting (0.996) and adsorption capacity agreement (62.26 mg g^?1). Furthermore, SG–ClPrNTf₂ phase was effectively performed for the determination of Au(III) in real water samples with satisfactory results.     

In situ synthesis and luminescence characteristics of complexes of europium(III) with 4,6-diacetylresorcinol

The complexes of europium(III) with 4,6-diacetylresorcinol (H₂DAR) and a co-ligand (phen, bpy or 2,2′-bipyridine N,N′-dioxide (2,2′-bpyO₂)) were in situ synthesized in silica matrix via a two-step gel process. The formation of complexes in silica gel was confirmed by the luminescence excitation spectra. The silica gels that contain in situ synthesized europium complexes exhibit the characteristic emission bands of the Eu(III). The results show that there are two ways to enhance the emission intensity of the Eu(III): (i) synthesize the complex in silica matrix and (ii) synthesize the complex with a co-ligand, which coordinates with Eu(III) in the composite system and can efficiently transfer the energy from 4,6-diacetylresorcinol to the Eu(III). The order of the luminescence intensities of the complexes is: Eu₂(DAR)₃(phen)₂-(sol–gel) > Eu₂(DAR)₃(2,2′-bpyO₂)₂-(sol–gel) > Eu₂(DAR)₃ (bpy)₂-(sol–gel) > Eu₂(DAR)₃-(sol–gel) > pure Eu₂(DAR)₃·4H₂O.     

Catalytic Decomposition of Organic Anions in Alkaline Radioactive Waste: 1. EDTA Oxidation

Decomposition of ethylenediaminetetraacetate in alkaline solutions with H₂O₂, Na₂S₂O₈, NaClO, and NaBrO was studied titrimetrically. EDTA is oxidized in solutions heated above 60°C in the presence of cobalt salts at stepwise addition of excess H₂O₂. The reaction between persulfate and EDTA has an induction period decreasing with increasing NaOH concentration and temperature and with decreasing initial EDTA content or with adding AgNO₃, K₄Fe(CN)₆, or NaNO₂. The process involves thermal dissociation of the persulfate ions into radical ions and the subsequent development of a chain reaction. Hypochlorite ions oxidize EDTA in 0.5-5.0 M NaOH at 25-60°C. The process efficiency can be improved by fractional addition of the oxidant in the presence of Co(II) or Ni(II) salts. EDTA is oxidized in alkaline solutions with hypobromite ions only on heating to 95°C. Salts of Co(II), Ni(II), and Cu(II) accelerate the process.     

Synthesis and Photoluminescence Properties of Eu3+‐Doped Silica@Coordination Polymer Core–Shell Structures and Their Calcinated Silica@Gd2O3:Eu and Hollow Gd2O3:Eu Microsphere Products

The conjugation of Eu³⁺‐doped coordination polymers constructed from Gd³⁺ and isophthalic acid (H₂IPA) with silica particles is investigated for the production of luminescent microspheres. A series of doping ratio‐controlled silica@coordination polymer core–shell spheres is easily synthesized by altering the amounts of metal nodes used in the reactions, where the ratios of Gd³⁺ and Eu³⁺ are 10:0 ( 1a ), 9:1 ( 1b ), 8:2 ( 1c ), 7:3 ( 1d ), 5:5 ( 1e ), and 0:10 ( 1f ). The formation of monodisperse uniform core–shell structures is achieved throughout the entirety of a series. Investigations of the photoluminescence property of the resulting series of silica@coordination polymer core–shell spheres reveal that 20% Eu³⁺‐doped product ( 1c ) has the strongest emission intensity. The subsequent calcination process on the silica@coordination polymer core–shell structures ( 1a ‐ f ) results in the formation of a series of doping ratio‐controlled silica@Gd₂O₃:Eu core–shell microspheres ( 2a ‐ f ) with uniform shell thickness. During the calcination step, the coordination polymers within silica@coordination polymer core–shells are transformed into metal oxides, resulting in silica@Gd₂O₃:Eu core–shell structures. The final etching process on the silica@Gd₂O₃:Eu core–shell microspheres ( 2a ‐ f ) produces a series of hollow Gd₂O₃:Eu microspheres ( 3a ‐ f ) as a result of the elimination of silica cores. The luminescence intensities of silica@Gd₂O₃:Eu core–shell ( 2a ‐ f ) and hollow Gd₂O₃:Eu microspheres ( 3a ‐ f ) also vary depending upon the doping ratio of Eu³⁺ ions.     

Kinetic energy release and mean life time of metastable ions produced from C3H3N

Metastable ions C₃H_nN⁺ (n = 1, 2 or 3) and C₂H₂⁺ produced by electron impact on the neutral C₃H₃N (acrylonitrile) undergo metastable decay reactions resulting in the fragment ions C₃H_mN⁺ (m = 1, 2) or C₂H₂⁺. We have monitored these reactions in a double focusing mass spectrometer of reversed B-E geometry. To identify the fragment ions and determine their kinetic energy release distribution (KERD), the mass-analyzed ion kinetic energy (MIKE) scan technique was utilized. For the above mentioned ions we obtained average KER values ranging from 9 up to 23 meV. Moreover, the fractions of decaying ions were measured. We have found the existence of two states of the metastable C₂H₂⁺ ion, one with a short life time of about 0.27 μs and the other one which is most likely a completely stable ion state.     

Study of Interaction between Technogenic Radionuclides and Floodplain Soils by Partitioning via Sequential Chemical Extraction

Several fractions of technogenic radionuclides were separated from floodplain soil by sequential extraction, among them radiocolloids of ⁶⁰Co and Eu nuclides associated with components of polymeric organomineral films [Fe(III) and Al(III) oxides and hydroxides] and organomineral complexes of ⁶⁰Co, ¹³⁷Cs, and Eu nuclides with humic compounds. Changing the oxidizing agent, H₂O₂, for chromic acid in the sequential extraction procedure allowed a considerable increase in the yield of the radionuclides to the solution: from 6.5 to 46% for ⁶⁰Co, from 1.4 to 36% for ¹³⁷Cs, and from 5.2-8.5 to 23-32% for the Eu isotopes.     

Adsorption of Eu(III) onto TiO2: Effect of pH,concentration, ionic strength and soil fulvic acid

The effects of pH, initial Eu(III) concentration, ionic strength and fulvic acid (FA) on the adsorption of Eu(III) on TiO₂ are investigated by using batch techniques. The results indicate that the presence of FA strongly enhances the adsorption of Eu(III) on TiO₂ at low pH values. Besides, the adsorption of Eu(III) on TiO₂ is significantly dependent on pH values and independent of ionic strength. The adsorption of Eu(III) on TiO₂ is attributed to inner-sphere surface complexation. The diffuse layer model (DLM) is applied to simulate the adsorption data, and fits the experimental data well with the aid of FITEQL 3.2. X-ray photoelectron spectroscopy (XPS) is performed to study the species of Eu(III) adsorbed on the surfaces of TiO₂/FA–TiO₂ hybrids at a molecular level, which suggest that FA act as “bridge” between Eu(III) and TiO₂ particles to enhance the ability to adsorb Eu(III) in solution.     

Effects of Ag colloidal nanoparticles on luminescent properties of Eu(III) β-diketone

Luminescent properties of Eu(TTA)₃·2H₂O complex (TTA: trifluorothenoyl-acetone) and Eu(DBM)₃·2H₂O complex (DBM: dibenzoylmethane) in MMA (methyl methacrylate) solution had been studied in the presence of Ag colloidal nanoparticles. Luminescence of Eu(TTA)₃·2H₂O complex was enhanced comparing to the Eu complex with the same concentration because it could aggregate around surface of Ag nanoparticles. Contrarily, luminescence of Eu(DBM)₃·2H₂O complex was quenched with increasing in Ag colloidal concentration. The results are attributed to different structures between TTA and DBM.     

Spectroscopic,thermal and biological studies of coordination compounds of sulfasalazine drug: Mn(II), Hg(II), Cr(III), ZrO(II), VO(II) and Y(III) transition metal complexes

The complexations of sulfasalazine (H₃Suz) with some of transition metals have been investigated. Three types of complexes, [Mn(HSuz)⁻²(H₂O)₄]·2H₂O, [M(HSuz)⁻²(H₂O)₂]·xH₂O (M = Hg(II), ZrO(II) and VO(II), x = 4, 8 and 6, respectively) and [M(HSuz)⁻²(Cl)(H₂O)₃]·xH₂O (M = Cr(III) and Y(III), x = 5 and 6, respectively) were obtained and characterized by physicochemical and spectroscopic methods. The IR spectra of the complexes suggest that the sulfasalazine behaves as a monoanionic bidentate ligand. The thermal decomposition of the complexes as well as thermodynamic parameters (δE*, δH*, δS* and δG*) were estimated using Coats-Redfern and Horowitz-Metzger equations. In vitro antimicrobial activities of the H₃Suz and the complexes were tested.     

Photoluminescence properties of the rare-earth ions in the TiO2 host nanofibers prepared via electrospinning

Luminescent rare-earth (RE) ions doped TiO₂ nanofibers have been prepared by electrospinning of a mixture solution of rare-earth acetylacetone (RE(C₅H₇O₂)₃)/titanium tetraisopropoxide (Ti (OiPr)₄)/poly(vinyl pyrrolidone) (PVP) (RE = Eu, Er, Ce, Pr), followed by calcination at high temperature. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray diffraction (XRD) analyses demonstrated the morphology and the structure of the rare-earth doped TiO₂ nanofibers. Exciting the nanofibers results in an energy transfer from surface states of TiO₂ to that of the rare-earth ions and the photoluminescence is observed from the crystal field states of the rare-earth ions.     

Synthesis, thermal, photoluminescent, and electroluminescent properties of a novel quaternary Eu(III) complex containing a carbazole hole-transporting functional group

A novel quaternary Eu(III) complex containing a carbazole fragment as hole-transporting functional group was synthesized, and its thermal stability, photoluminescent (PL), electroluminescent (EL) properties were studied. Its glass transition temperature (T _g) was 131 °C and 5% weight loss temperature was 325 °C. In studies of its EL properties, two devices with the Eu(III) complex as red light-emitting materials were fabricated and measured. Device 1: ITO/NPB (40 nm)/Eu(III) complex (30 nm)/Alq₃ (30 nm)/LiF (0.7 nm)/Al (100 nm), NPB was N,N′-di(naphthalene-1-yl)-N,N′-diphenyl-benzidine as the hole-transporting layer, Alq₃ was tris(8-hydroxyquinoline) aluminum as the electron-transporting layer. Device 1 gave two emission bands of the Eu(III) complex and Alq₃ with the maximum luminance of 437 cd/m² at 17.34 V, and its turn-on voltage was 10 V. In device 2, an electron-transporting/hole-locking layer of BCP (2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline, 30 nm) was added between the Eu(III) complex and Alq₃ layers, only a sharp red emission band of the Eu(III) complex was given with the maximum luminance of 186 cd/m² at 20.08 V, and its turn-on voltage was 12 V.     

Formal oxidation potentials of actinide couples in K<Subscript>10</Subscript>P<Subscript>2</Subscript>W<Subscript>17</Subscript>O<Subscript>61</Subscript> solutions

The formal oxidation potentials of the M(VI)/M(V), M(V)/M(IV), and M(IV)/M(III) couples for actinides from U to No and of the M(IV)/M(III) couples for some actinides in 1 M H⁺ or 1 M Na⁺ (pH ～5–5.5) solutions containing K₁₀P₂W₁₇O₆₁ were calculated from the data on stability of complexes of f element ions with the unsaturated heteropolytungstate anion P₂W₁₇O ₆₁ ^10? . In some cases, the previously accepted values were subjected to major revision, especially the potentials of the An(V)/An(IV) couples. Problems arising in measuring the potentials of the couples involving Np(III) and Pu(III) which react with the heteropolyanion to form a heteropoly blue are discussed. The potentials of some M(III)/M(II) couples are estimated.