Synthesis,characterization and ion exchange properties of zirconium(IV) tungstoiodophosphate,a new cation exchanger

Zirconium(IV) tungstoiodophosphate has been synthesized under a variety of conditions. The most chemically and thermally stable sample is prepared by adding a mixture of aqueous solutions of 0·5 mol L⁻¹ sodium tungstate, potassium iodate and 1 mol L⁻¹ orthophosphoric acid to aqueous solution of 0·1 mol L⁻¹ zirconium(IV) oxychloride. Its ion exchange capacity for Na⁺ and K⁺ was found to be 2·20 and 2·35 meq g⁻¹ dry exchanger, respectively. The material has been characterized on the basis of chemical composition, pH titration, Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis. The effect on the exchange capacity of drying the exchanger at different temperatures has been studied. The analytical importance of the material has been established by quantitative separation of Pb²⁺ from other metal ions.     

Sorption of Th,U, and Am on phosphorus-containing ion-exchange materials

Sorption of Th, uranyl, Am, Fe, and Al ions from nitric acid solutions on various phosphorus-containing ion-exchange materials (organic ion-exchange resins, SE-UPO solid extractant) was studied. The highest selectivity to quadruple-charged metal cations is exhibited by S-957 cation exchanger (Purolite) with phosphonic and sulfonic acid groups. The capacity of this resin for Th is essentially independent of the HNO₃ concentration in the range 1–7 M and amounts to 80–95 mg ml⁻¹. The uranyl, Am, Fe, and Al ions are sorbed on S-957 resin considerably worse than Th. The internal diffusion coefficient of Th⁴⁺ ions in S-957 resin from 3 M HNO₃ was determined to be (5.3 ± 0.5) × 10⁻¹³ m² s⁻¹. The IR spectra of S-957 resin in the hydrogen and thorium forms were recorded. S-957 resin shows promise for selective recovery of tetravalent actinides from multicomponent nitric acid-salt solutions.     

Microwave sample preparation of facing materials for analysis using the method of atomic emission spectroscopy with inductively coupled plasma

A technique for microwave decomposition of the powder for plasma-jet hard-facing and determination of boron, iron (III), and chromium (III) by ICP-AES is presented. The solvent composition and parameters of the microwave decomposition of the samples in an autoclave are optimized. The detection limits for B, Cr (III) and Fe (III) are 3.0 × 10⁻³, 7.6 × 10⁻⁵, and 2.0 × 10⁻² wt %, respectively.     

New approaches to reprocessing of oxide nuclear fuel

Dissolution of UO₂, U₃O₈, and solid solutions of actinides in UO₂, including those containing Cs, Sr, and Tc, in weakly acidic (pH 0.9–1.4) aqueous solutions of Fe(III) nitrate or chloride was studied. Complete dissolution of the oxides is attained at a molar ratio of Fe(III) nitrate or chloride to uranium of 1.6 or 2.0, respectively. In the process, actinides pass into the solution in the form of U(VI), Np(V), Pu(III), and Am(III). At 60°C, actinide oxides dissolve in these media faster than at room temperature. In the solutions obtained, U(VI) and Pu(III) are stable both at room temperature and at elevated temperatures (60°C), and also at high U concentrations (up to 300 mg ml⁻¹) typical of process solutions (6–8 M HNO₃, ∼60–80°C). After the oxide fuel dissolution, U and Pu are recovered from the solution by peroxide precipitation. In so doing, the content of Fe, Tc, Cs, and Sr in the precipitate does not exceed ∼0.05 wt %. From the solution after the U and Pu separation, the fission lanthanides, Tc, Cs, and Sr can be recovered by precipitation of Fe hydroxides in the presence of ferrocyanide ions and can be immobilized in appropriate matrices suitable for long-term and environmentally safe storage.     

New membrane for copper-selective electrode incorporating a new thiophosphoril-containing macrocycle as neutral carrier

The new macrocycles 4-phenyl-11-(1-oxodecyl)-1,7-dithia-11-aza-4-phosphacyclotetradecane (III) and 4-phenyl-4-sulfide-11-(1-oxodecyl)-1,7-dithia-11-aza-4-phosphacyclotetradecane (IV) have been synthesised and characterised. Through their use as ionophore in an all-solid state poly(vinylchloride) matrix membrane electrode, the ability of IV as cation receptor has been studied. The electrode exhibits a Nernstian response towards copper (II) ions with a cationic slope of 30.7 ± 1.7 mV per decade, over the concentration range 3.0 × 10^− 6 to 1.0 × 10^− 2 M and the potential response remains almost unchanged over the pH range 3.9–6.4. The electrode can be used for at least seven months without a considerable alteration in its potential.     

Structural and electrical properties of swift heavy ion beam irradiated Fe/Si interface

The present work deals with the mixing of iron and silicon by swift heavy ions in high-energy range. The thin film was deposited on a n-Si (111) substrate at 10⁻⁶ torr and at room temperature. Irradiations were undertaken at room temperature using 120 MeV Au⁺⁹ ions at the Fe/Si interface to investigate ion beam mixing at various doses: 5 × 10¹² and 5 × 10¹³ ions/cm². Formation of different phases of iron silicide has been investigated by X-ray diffraction (XRD) technique, which shows enhancement of intermixing and silicide formation as a result of irradiation. I-V measurements for both pristine and irradiated samples have been carried out at room temperature, series resistance and barrier heights for both as deposited and irradiated samples were extracted. The barrier height was found to vary from 0·73–0·54 eV. The series resistance varied from 102·04–38·61 kΩ.     

Fabrication of an iron(III) PVC-membrane sensor based on bis-benzilthiocarbohydrazide as a selective sensing material

The construction, performance characteristics, and application of a novel iron(III) membrane sensor based on a new bis-benzilthiocarbohydrazide (BBTC) are reported in this paper. The sensor is prepared by incorporating of BBTC, nitrobenzene (NB), and sodium tetraphenyl borate (NaTPB) into a plasticized poly(vinyl chloride) membrane. The electrode reveals a Nernstian behavior over a wide iron ion concentration range (1.0 × 10^? 2–1.0 × 10^? 7 mol L^? 1), and relatively low detection limit (8.6 × 10^? 8 mol L^? 1). The potentiometric response is independent on the pH of the solution in the range of 1.6–4.3. The electrode shows a very short response time (< 10 s). The proposed electrode can be used for at least nine weeks without any considerable divergence in potentials. It exhibits very good selectivity relative to a wide variety of alkali, alkaline earth, transition and heavy metal ions. In fact, the selectivity of the proposed sensor shows great improvements compared to the previously reported electrodes for the iron ion. Also, the sensors accuracy was investigated in two ways: (i) with the potentiometric titration of a Fe(III) solution with EDTA and (ii) with the Fe(III) monitoring in river and wastewater samples.     

Oxidation of carbohydrazide with nitric acid

The kinetics of carbohydrazide oxidation with nitric acid in aqueous solutions was studied. In the range [HNO₃] = 3–7 M, the reaction rate is described by the equation −d[(NH₂NH)₂CO]/dt = k[(NH₂NH)₂CO][HNO₃] ⁿ , where n = 3.6 and 2.9 at 70 and 90°C, respectively. The constant k = (6.65 ± 0.23) × 10⁻⁴ l^2.9 mol^−2.9 h⁻¹ at 90°C, and the activation energy of the reaction in 7 M HNO₃ is 124 kJ mol⁻¹. The Fe(III) and especially Tc(VII) ions considerably accelerate the reaction, whereas the uranyl ions accelerate it insignificantly. The reaction mechanism in which the reactive species oxidizing carbohydrazide is nitronium ion NO₂⁺ was suggested.     

Heptadentate Schiff-base based PVC membrane sensor for Fe(III) ion determination in water samples

Tests performed using heptadentate Schiff's base ((tris(3-(thiophenal)propyl)amine (TTA)) toward Fe(III) ions indicated that it could be used as an Fe(III) selective ionophore to be used in a plasticized polymeric membrane sensor. The resulting sensors were found to produce a linear response range of five orders of magnitude with a slope of 19.8 ± 0.3 mV decade^− 1 with a detection limit is 8.3 × 10^− 9 mol L^− 1. The sensor could be used in a pH window of 2.4-4.3 and the response time of the sensor was below 10 s, in addition to its very good Fe(III) selectivity over many mono-,di- and trivalent transition and heavy metal ions. The life time of the electrode was found to be at least 10 weeks.     

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.     

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.     

Mn valence state and electrode performance of perovskite-type cathode La0·8Sr0·2Mn1 − x Cu x O3 − δ (x = 0, 0·2) for intermediate-temperature solid oxide fuel cells

Cu-free and Cu-doped LSM system, La_0·8Sr_0·2Mn_1???x Cu _x O_3???δ (x?=?0, 0·2), with perovskite structure were prepared using an EDTA combined citrate process and the effects of Cu ion at B-site were investigated. Electrical conductivity and polarization resistance of the Cu-doped LSM were 210 S·cm^???1 at 750 °C, and 2·54 Ω · cm² at 800 °C, respectively which were better than those of the Cu-free LSM. This indicated that the electrode performance of LSM was improved by the addition of Cu. The oxidation state of Mn ions increased with addition of Cu. The increase in the oxidation state of Mn ions was due to the formation of Mn^4?+? ions and oxygen vacancies. The addition of Cu ions to LSM systems could lead to enhanced electrode performance for oxygen reduction reactions originating from the change in valence of Mn ions.     

A novel lutetium(III) PVC membrane sensor based on a new symmetric S–N Schiff's base for Lu(III) analysis in real sample

A novel Lu(III) PVC membrane sensor has been constructed based on a new synthesized symmetric S–N Schiff's base, namely N-[(Z)-1-(2-thienyl)methylidene]-N-[4-(4-{[(Z)-1-(2-thienyl) methylidene]amino}benzyl)phenyl] amine (TBPA). The electrode showed a Nernstian slope of 19.8 ± 0.5 mV per decade across a wide concentration range of 1.0 × 10^? 6 to 1.0 × 10^? 2 mol L^? 1 with a detection limit of 7.2 × 10^? 7 mol L^? 1. The proposed sensor showed high selectivity toward Lu(III) ion in comparison with common alkaline, alkaline earth, transition, and heavy metals specially lanthanide ions, and could be used over a pH range of 2.7–10.6. It can be used for at least 2 months without any considerable divergency in potentials and it has a relatively fast response time of < 10 s. The sensor was effectively used as an indicator electrode in the potentiometric titration of Lu(III) ions with EDTA. The constructed sensor accuracy was investigated by the monitoring of Lu(III) ion in mixtures of two and three different ions.     

Investigation of electrical conduction in polyvinyl formal

Current-voltage (I–V) characteristics of pure polyvinyl formal (PVF) were investigated at different fields, range 5–100 kV/cm, as a function of temperature, range 313–363 K. It was observed that while at low fields (up to 25 kV/cm), the conduction was Ohm’s law-dependent at high fields (beyond 25 kV/cm), the conduction was Poole-Frenkel (P-F) mechanism-dependent. An attempt was made to identify the nature of the current by comparing its observed dependence on temperature, electric field and electrode materials with their respective characteristic features of the existing theories of electrical conduction. The current showed a strong dependence on temperature. To identify the possible mechanism of conduction, current versus square root of field characteristics were drawn with aluminium, silver, copper and gold as upper electrodes and Al as the lower electrodes. The observed characteristic suggested that the charge carriers were generated by the field-assisted lowering of coulombic barriers at the traps, and were subsequently conducted through the bulk of the material by a hopping process between the localized states by a Jonscher-Ansari-modified P-F mechanism. The calculated value of the modified P-F barrier was ⋍ 1·94×10⁻¹⁹ J (1·21 eV).     

Potentiometric studies of N,N′-Bis(2-dimethylaminoethyl)-N,N′-dimethyl-9,10 anthracenedimethanamine as a chemical sensing material for Zn(II) ions

A liquid membrane based Zn²⁺ ion selective electrode containing N,N′-Bis(2-dimethylaminoethyl)-N,N′-dimethyl-9,10 anthracenedimethanamine (Bis(TMEDA) anthracene) (I) as ionophore has been prepared and characterized. The membrane comprises of PVC, ionophore and plasticizer in the ratio of 33:2:65, respectively. It showed the best response in terms of detection limit (1.5 × 10^− 6 M) and working concentration range (1.0 × 10^− 5 M to 1.0 × 10^− 1 M) with Nernstian response towards Zn²⁺ ions. The electrode responds within 15 s of coming in contact with the solution. The potential response remains almost unchanged over a pH range of 3.0 to 7.5. The electrode can be used for at least 3 months without any considerable alteration in its response behavior. The proposed electrode revealed good selectivity towards Zn²⁺ ions over a number of alkali, alkaline earth, transition metals and some other heavy metal ions. The electrode has been used as an indicator electrode in the potentiometric titration of Zn²⁺ with EDTA. The proposed electrode also detected Zn²⁺ ions from real life samples.     

Effect of salts on oxidation of Np(VI) with Fe(CN)<Stack><Subscript>6</Subscript><Superscript>3−</Superscript></Stack> Ions in 0.1–1 M alkali solutions

The potential of the Fe(CN)₆³⁻/Fe(CN)₆⁴⁻ couple in solutions containing 0.5–1 M alkali and high concentrations of Li, Na, and K salts was estimated potentiometrically. The reactions of Fe(CN)₆³⁻ with Np(VI) in such media were studied by spectrophotometry. In 0.5–1 M KOH + 7 M KF or 0.5–1 M KOH + 8 solutions, Np(VI) is oxidized to the heptavalent state with a small excess of Fe(CN)₆³⁻. In the presence of lithium or sodium salts, a larger excess of the oxidant is required for complete oxidation of Np(VI). Carbonate ions in concentrations exceeding 2 M prevent the Np(VI) oxidation.     

Di-tert-butylazodicarboxylate based PVC membrane sensor for Fe(III) ion measurement in pharmaceutical formulation

Preliminary solution study shows the selectivity of di-tert-butylazodicarboxylate (TBADC) toward Fe(III) ions. Due to this selectivity, it was applied as an ionophore for construction of a Fe(III) sensor. The proposed sensor exhibits a wide linear response range with a Nerstian slope of 19.4 ± 0.4 mV decade^− 1 and detection limit of 4.8 × 10^− 8 mol L^− 1. The sensor response is pH independent in the range of 2.3-3.4 and has a fast response time of < 10 s. It also shows very good selectivity to Fe(III) ion over many mono-,di- and trivalent transition and heavy metal ions. The life time of the electrode was at least 10 weeks. The application of the TBADC-based sensor to analysis of Fe(III) ion in a pharmaceutical formulation, and also to the monitoring of Fe(III) ion in mixtures of two, three and four different ions showed satisfactory results.     

Preparation, characterization and luminescent properties of europium oxide doped nano LaMn0·9Zn0·1O3+d by sol-gel processing

New compounds of rare earth complex oxides with perovskite structure in a combination of La with Eu ions and Mn with Zn ions, La_1−x Eu _x Mn_0·9Zn_0·1O_3+d (LEMZ) (0·0 ≤ x ≤ 0·32) in A and B sites, respectively were synthesized. X-ray powder diffraction (XRD), fourier transform infrared spectroscopy (FT-IR) and photoluminescence spectra (PL) were used to characterize the resulting nanoparticles. The powder X-ray diffraction peaks could be indexed as a rhombohedral cell. The results of FT-IR spectra were in agreement with those of XRD. High-quality nanopowders with controlled stoichiometry and microstructure were prepared at a temperature range of 700–800°C for 6 h, with mean particle sizes of ∼ 17·5 nm. Photoluminescence measurements showed Eu³⁺ ions characteristic red emission in crystalline LEMZ powders due to the ⁵ D ₀ → ⁷ F _J (J = 0–6) transitions of the 4f electrons of Eu³⁺ ions. The structure, homogeneity and particle size of the obtained compounds during different stages were investigated by scanning electron microscopy (SEM).     

The reaction Pu(VI) + Fe(CN)<Stack><Subscript>6</Subscript><Superscript>3−</Superscript></Stack> ⇄ Pu(VII) + Fe(CN)<Stack><Subscript>6</Subscript><Superscript>4−</Superscript></Stack> in NaOH solutions

A spectrophotometric study showed that, in 5 M NaOH, Pu(VII) prepared by ozonation of Pu(VI) is reduced with excess K₄Fe(CN)₆. The Pu(VII) content can be estimated from the amount of the Fe(CN)₆³⁻ formed. In NaOH solutions of concentration exceeding 8 M, the Fe(CN)₆³⁻ ion oxidizes Pu(VI). In 10.3 M NaOH, the tenfold excess of K₃Fe(CN)₆ fully converts 1 mM Pu(VI) to the heptavalent state within 4 min (rate constant 1.3 l mol⁻¹ s⁻¹ at 20°C). With an increase in the NaOH concentration, the oxidation rate increases, and smaller excess of K₃Fe(CN)₆ is required. This oxidant is consumed not only for Pu(VI) oxidation but also in reactions with H₂O and OH⁻ ions. Pu(VII) is unstable and is slowly reduced with water and with products of decomposition of iron complexes.     

Application of 1-ethyl-3-(2,5-dihydro-4-(3,5-dimethyl-1H-pyrazol-4-yl)-5-oxo-1H-pyrazol-3-yl)thiourea as sensing material for construction of Tm3+-PVC membrane sensor

A thulium(III) membrane sensor was made using 2% sodium tetraphenyl borate (NaTPB), 65% dibutylphthalate (DBP), 30% poly(vinyl chloride) (PVC) and 3% 1-ethyl-3-(2,5-dihydro-4-(3,5-dimethyl-1H-pyrazol-4-yl)-5-oxo-1H-pyrazol-3-yl)thiourea (ET) as an ionophore. Conductometric study shows selectivity of the Et toward Tm³⁺ ions. Nernstian response of 19.6 ± 0.4 mV per decade of thulium concentration was observed, and the electrode worked well in concentration range of 1.0 × 10^? 6 to 1.0 × 10^? 2 mol L^? 1 with a lower detection limit (LDL) of 7.2 × 10^? 7 mol L^? 1, in a pH range of 4.3–10.4. The selectivity of the sensor over alkaline, alkaline earth, transition and heavy metal ions was also found to be in a satisfactory range. To check the analytical applicability of the proposed Tm³⁺ sensor, it was successfully used as an indicator electrode in analysis of thulium in certified reference materials.