Sodium Tellurite Research Articles

An improved hydrometallurgical route for tellurium production

In recent years, tellurium has been extensively used in the manufacture of semiconductor materials. For this type of application, high-purity tellurium is required. Selenium, lead and silicon are usually the main impurities in tellurium. During the electrolytic refining of copper, tellurium gold and silver are collected in the anode slimes. A pyrometallurgical treatment is used to recover gold and silver from the decopperized anode slimes whereas tellurium is oxidized and skimmed off from the refining furnace as a Na2CO3-based slag. In the slag, tellurium is present as sodium tellurite (Na2TeO3), which is further water-leached from the slag. The first step in the conventional process for tellurium recovery consists of the precipitation of the tellurium contained in the leaching solution as tellurium dioxide (TeO2). The solid TeO2 is then dissolved under acidic conditions for its further reduction with sulfur dioxide gas (SO2). In this paper, an alternative route for tellurium production is presented in which a sodium tellurate [Na2TeO4] intermediate is obtained by oxidation of the sodium tellurite in an alkaline solution following the water leaching step. Sodium tellurate is then dissolved in acid media and high-purity tellurium is obtained by reduction with SO2 gas. Experimental tests under laboratory conditions indicate that the novel process yields higher precipitation selectivity for tellurium than the conventional process. A comparison of its efficiency concerning impurities co-precipitation with respect to the conventional process is discussed.

A Human Stem Cell-Based Model for Identifying Adverse Effects of Organic and Inorganic Chemicals on the Developing Nervous System

The aim of our study was to investigate whether a human neural stem cell line derived from umbilical cord blood (HUCB-NSC) can serve as a reliable test model for developmental neurotoxicity (DNT). We assessed the sensitivity of HUCB-NSCs at different developmental stages to a panel of neurotoxic (sodium tellurite, methylmercury chloride, cadmium chloride, chlorpyrifos, and L-glutamate) and non-neurotoxic (acetaminophen, theophylline, and D-glutamate) compounds. In addition, we investigated the effect of some compounds on key neurodevelopmental processes like cell proliferation, apoptotic cell death, and neuronal and glial differentiation. Less differentiated HUCB-NSCs were generally more sensitive to neurotoxicants, with the notable exception of L-glutamate, which showed a higher toxicity to later stages. The relative potencies of the compounds were: cadmium chloride > methylmercury chloride >> chlorpyrifos >> L-glutamate. Fifty nanomolar methylmercury chloride (MeHgCl) inhibited proliferation and induced apoptosis in early-stage cells. At the differentiated stage, 1 muM MeHgCl induced selective loss of S100 beta-expressing astrocytic cells. One millimolar L-glutamate did not influence the early stages of HUCB-NSC development, but it affected late stages of neuronal differentiation. A valuable system for in vitro DNT assessment should be able to discriminate between neurotoxic and non-neurotoxic compounds and show different susceptibilities to chemicals according to developmental stage and cell lineage. Although not exhaustive, this work shows that the HUCB-NSC model fulfils these criteria and may serve as a human in vitro model for DNT priority setting.

Axial-Junction Nanowires of Ag2Te−Ag As a Memory Element

Silver telluride nanowires incorporating silver were prepared by green chemical method in aqueous solution. First, Ag2TeO3 was prepared from aqueous solutions of sodium tellurite (Na2TeO3) and silver nitrate (AgNO3). At room temperature in basic solution, α-d-glucose reduces Ag2TeO3 to generate silver nanocrystals, whereas solvothermal reaction of Ag2TeO3 with α-d-glucose at 165 °C generates Te, Ag, or Ag2Te−Ag axial hetrojunction nanowires depending upon the pH of the reaction mixture. These heterojunction nanowires, which exhibit electrical bistability at low voltage, can be used as data storage devices.

Effect of nano-scale crystal field on the broadening of Er^3+- emission in sodium tellurite glass ceramics

In this paper we report the effect of heat treatment of 10 mol% Na(2)O-89.5 mol% TeO(2) glass for studying the fluorescence and line broadening behavior of Er-ions in the glass-ceramic matrix. Controlled crystal growth measurements using the X-ray line broadening technique for samples heat treated in the temperature range of 583-693 K were carried out and compared with the photoluminescence studies. The influence of crystal growth on line broadening of (4)I(13/2) spectra and metastable lifetime of (4)I(13/2) level is compared for various heat treatment temperatures. The full-width-of- half maxima increase with increasing heat treatment temperature and then fall rapidly at high temperatures.

Synthesis and Bio-Imaging Application of Highly Luminescent Mercaptosuccinic Acid-Coated CdTe Nanocrystals

Here we present a facile one-pot method to prepare high-quality CdTe nanocrystals in aqueous phase. In contrast to the use of oxygen-sensitive NaHTe or H2Te as Te source in the current synthetic methods, we employ more stable sodium tellurite as the Te source for preparing highly luminescent CdTe nanocrystals in aqueous solution. By selecting mercaptosuccinic acid (MSA) as capping agent and providing the borate-citrate acid buffering solution, CdTe nanocrystals with high quantum yield (QY >70% at pH range 5.0–8.0) can be conveniently prepared by this method. The influence of parameters such as the pH value of the precursor solution and the molar ratio of Cd2+ to Na2TeO3 on the QY of CdTe nanocrystals was systematically investigated in our experiments. Under optimal conditions, the QY of CdTe nanocrystals is even high up to 83%. The biological application of luminescent MSA-CdTe to HEK 293 cell imaging was also illustrated.

DNA-damage induction by eight metal compounds in TK6 human lymphoblastoid cells: Results obtained with the alkaline Comet assay

Metal compounds are long-lived and can react with different macromolecules, producing a wide range of biological effects, including DNA damage. Since their reactivity is associated with their chemical structure, it is important to obtain information on more than one compound from the same metal. In this study, the DNA-damaging potential of two mercury compounds (mercury chloride and methyl mercury chloride), two nickel compounds (nickel chloride and potassium hexafluoronickelate), two palladium compounds (ammonium tetrachloropalladate and ammonium hexachloropalladate), and two tellurium compounds (sodium tellurite and sodium tellurate) was evaluated in human lymphoblastoid TK6 cells by use of the alkaline version of the Comet assay. As the use of computerized image-analysis systems to collect comet data has increased, the metric used for quantifying DNA damage was the Olive tail moment. Treatments lasted for 3 h and the range of concentrations tested was different for each metal compound, depending on its toxicity. Both mercury agents produced DNA damage in TK6 cells, with mercury chloride producing considerably more DNA damage than methyl mercury chloride. Of the two nickel compounds, only nickel chloride (a Ni(II) compound) induced DNA breaks. Similarly, of the two palladium compounds, only the Pd(II) compound (ammonium tetrachloropalladate) was positive in the assay. Sodium tellurite was clearly positive, producing concentration-related increases in DNA damage, while sodium tellurate gave a negative response. In conclusion, the ability of inducing DNA damage by the selected metal compounds in human TK6 cells, when measured with the Comet assay, was dependent on the chemical form and, in general, compounds containing the metal in the lower valence state displayed the greater DNA-damaging ability.

Second-Harmonic Generation in Thermally Poled Na2O-Al2O3-TeO2 Glasses

Tellurite glasses exhibit attractive optical properties such as high refractive index, high transmittance in the infrared-to-visible region, and large third-order nonlinear susceptibility. Poled tellurite glasses also show second-harmonic generation (SHG) as revealed by the present authors. However, there exist many unresolved problems in second-harmonic generation of oxide glasses; SH intensity is low and it decays at room temperature. In this work, the effect of Al2O3 addition on SH intensity and its decay has been explored for thermally poled sodium tellurite glasses. The decay rate of SH intensity is reduced by the addition of Al2O3. The result is similar to those reported for phosphate and silicate glasses containing Al2O3. Also, the glasses poled at a voltage of 4 kV manifest optimum poling temperature lower than that for the same glasses poled at 3 kV.

Effects of selenium and tellurium on the activity of selenoenzymes glutathione peroxidase and Type I iodothyronine deiodinase, trace element thyroid level, and thyroid hormone status in rats

Tellurium (Te) and selenium (Se) belong chemically to the VIa group of elements. Se represents an essential element closely related to thyroid function. Te has growing application in industrial processes. Little is known about the Te biological activity, particularly with respect to potential chemical interactions with Se-containing components in the organism. In this study, female Wistar rats (body weight: 115-120 g) received sodium selenite pentahydrate (10 mg/L) or sodium tellurite (9.4 mg/L) in drinking water for 6 wk. Additional groups of rats received their combination with zinc sulfate heptahydrate (515 mg/L). The stimulation of 5'-DI-I activity due to selenite (to 158%, p<0.01) or tellurite treatment (to 197%, p<0.01) was seen; however, no effect on glutathione peroxidase was demonstrated in this experiment. An elevation of T4, T3, and rT3 serum levels was measured in the Se+Te-treated group; T4 and rT3 levels were elevated in the Te+Zn-treated group. Te accumulates in the thyroid gland and influences the zinc thyroid level. Te treatment alone and in combination with Se or Zn decreased the iodine thyroid concentration to 65-70% of the control value. Further studies are needed to clarify the nature and effects of these events.

Vibrational modes of sodium–tellurite glasses: Local structure and Boson peak changes

Raman spectra of xNa 2O−(1− x)TeO 2 glasses were measured and analyzed over a broad composition range. The network structure of the glass consists of a mixture of TeO 4 trigonal bipyramids and TeO 3 trigonal pyramidal units. Increase of alkali content results in conversion of the TeO 4 units into TeO 3 units with a varying number of non-bridging oxygen atoms. This local structure transformation becomes more evident at x=0.2, where rigidity percolation theory predicts a threshold for the rigid-to-floppy transition. However, other spectral features such as the composition dependence of the energy of the Boson peak do not support the occurrence of the stiffness transition. The controversial dependence of dynamical parameters such as the fragility index as a function of Na 2O concentration is also discussed.

Identification of urinary tellurium metabolite in rats administered sodium tellurite

Download options Please wait... Article information DOI https://doi.org/10.1039/B613835G Article type Paper Submitted 22 Sep 2006 Accepted 21 Nov 2006 First published 11 Dec 2006 Download Citation J. Anal. At. Spectrom., 2007,22, 153-157 BibTex EndNote MEDLINE ProCite ReferenceManager RefWorks RIS Permissions Request permissions Identification of urinary tellurium metabolite in rats administered sodium tellurite Y. Ogra, R. Kobayashi, K. Ishiwata and K. T. Suzuki, J. Anal. At. Spectrom., 2007, 22, 153 DOI: 10.1039/B613835G To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page. If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given. If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page. Read more about how to correctly acknowledge RSC content. Social activity Tweet Share Search articles by author Yasumitsu Ogra Reina Kobayashi Kazuya Ishiwata Kazuo T. Suzuki

Characterization of nanocrystalline cadmium telluride thin films grown by successive ionic layer adsorption and reaction (SILAR) method

Structural, electrical and optical characteristics of CdTe thin films prepared by a chemical deposition method, successive ionic layer adsorption and reaction (SILAR), are described. For deposition of CdTe thin films, cadmium acetate was used as cationic and sodium tellurite as anionic precursor in aqueous medium. In this process hydrazine hydrate is used as reducing agent and NH4OH as the catalytic for the decomposition of hydrazine. By conducting several trials optimization of the adsorption, reaction and rinsing time duration for CdTe thin film deposition was done. In this paper the structural, optical and electrical properties of CdTe film are reported. The XRD pattern shows that films are nanocrystalline in nature. The resistivity is found to be of the order of 411 × 103 Ω-cm at 523 K temperature with an activation energy of ∼ 0.2 eV. The optical absorption studies show that films have direct band gap (1.41 eV).

Optical hole burning studies in europium doped oxide glasses

Europium doped sodium borate, silicate, borosilicate, germanate and tellurite glasses have been prepared by melt quenching technique. Optical spectroscopy techniques were used to characterize the divalent and trivalent ions. Optical hole burning technique was used to characterize rare-earth ion doped glasses for optical data storage. The hole burning mechanisms, which depend on the glass composition and the preparation methods used, are discussed.

Phenotype Microarray Profiling of Staphylococcus aureus menD and hemB Mutants with the Small-Colony-Variant Phenotype

Standard biochemical tests have revealed that hemin and menadione auxotrophic Staphylococcus aureus small-colony variants (SCVs) exhibit multiple phenotypic changes. To provide a more complete analysis of the SCV phenotype, two genetically defined mutants with a stable SCV phenotype were comprehensively tested. These mutants, generated via mutations in menD or hemB that yielded menadione and hemin auxotrophs, were subjected to phenotype microarray (PM) analysis of over 1,500 phenotypes (including utilization of different carbon, nitrogen, phosphate, and sulfur sources; growth stimulation or inhibition by amino acids and other nutrients, osmolytes, and metabolic inhibitors; and susceptibility to antibiotics). Compared to parent strain COL, the hemB mutant was defective in utilization of a variety of carbon sources, including Krebs cycle intermediates and compounds that ultimately generate ATP via electron transport. The phenotype of the menD mutant was similar to that of the hemB mutant, but the defects in carbon metabolism were more pronounced than those seen with the hemB mutant. In both mutant strains, hexose phosphates and other carbohydrates that provide ATP in the absence of electron transport stimulated growth. Other phenotypes of SCV mutants, such as hypersensitivity to sodium selenite, sodium tellurite, and sodium nitrite, were also uncovered by the PM analysis. Key results of the PM analysis were confirmed in independent growth studies and by using Etest strips for susceptibility testing. PM technology is a new and efficient technology for assessing cellular phenotypes in S. aureus.

Te@Cross-Linked PVA Core−Shell Structures Synthesized by a One-Step Synergistic Soft−Hard Template Process

Recently, we proposed a simple, large-scale hydrothermal synthesis of flexible nanocables with silver as cores and cross-linked poly(vinyl alcohol) (PVA) as shells in which silver ions catalyzed the cross-linking of PVA chains under hydrothermal conditions and a so-called synergistic soft−hard template mechanism (SSHM) was proposed (Luo et al. J. Am. Chem. Soc. 2005, 127, 2822−2823). In this paper, we extend this approach to examine whether high valent metal ions such as Te4+ also can be reduced under a similar reaction but using sodium tellurite and PVA as precursors. The results demonstrated that different tellurium/cross-linked PVA core−shell nanostructures such as a core−shell structure with nanorod bundles penetrated through a ball, branched cables, and separated cables can be synthesized. The influence of the concentration of PVA, reaction temperature, and reaction time on the formation of different nanostructures has been investigated. In addition, the detailed reaction and shape evolution process of core−shell structures have also been studied. The results suggested that the cross-linking of PVA also can occur in the presence of high valent metal ions besides noble metal ions, underlining that it is possible to access various core−shell structures with different inorganic components as cores by this approach.

Microspheres of Tellurite Glass Formed by Evaporation–Condensation Process under High Magnetic Field

Sodium tellurite glass was evaporated by irradiating a CO2 laser beam under a high magnetic field with a large gradient. Glass microspheres were formed as a cloud of soot with the condensation of the vapor from the source glass. The flow of the glass soot due to thermal convection was observed when the glass source was evaporated under a zero field, but was suppressed by applying the high magnetic field with a large gradient, which reduces gravity for the glass by a magnetic force of -0.8g in the gravitational scale. The maximum size of the microspheres decreased to about half that of microspheres formed under a zero field. Sodium concentration in the microspheres was found to increase with magnetic field. A disturbance of the motion of evaporated species due to electromagnetic force was suggested as an origin of the suppression of recondensation to the surface of source glass melt under the high magnetic field, resulting in the increase in the sodium concentration of the microspheres and in the decrease in their size.

Persistent spectral hole burning in europium-doped sodium tellurite glass

We have prepared sodium tellurite glasses doped with europium. Emission intensity of the europium-doped glass is at least 500× more than that of the undoped glass. Fluorescence features exhibited dependence on the pump laser wavelength. Persistent spectral hole burning was observed in the F07→D05 transition of Eu3+. Multiple hole burning was possible even if the chemicals were melted in ambient air to make the glass. The hole burning mechanism is also explained. Electron spin resonance measurements confirmed the existence of defect centers.

Ionic conductivity and conductivity relaxation of potassium tellurite glasses

AbstractThe electrical conductivity and conductivity relaxation of xK2O–(100–x)TeO2 glasses have been investigation in the frequency range 40 Hz to 200 kHz and temperature range 300 to 473 K. From the density and molar volume, it may be noticed that with increasing K2O content the density decreases while the molar volume increases highlighting the fact that more nonbridging oxygens (NBOs) are formed in the network as the concentration of K2O is increased. The Anderson–Stuart model was employed to explain the dc activation energy. The frequency‐dependent electrical data have been analyzed in the framework of the conductivity and modulus formalisms. The decrease of the conductivity relaxation time with increasing content of K2O was explained in the framework of the structural model of tellurite glasses. The variation of the stretched exponential parameter β with composition was compared with those of lithium and sodium tellurite glasses and was explained in terms of cation–cation distance correlation. (© 2005 WILEY‐VCH Verlag GmbH &amp; Co. KGaA, Weinheim)

A 125Te and 23Na NMR investigation of the structure and crystallisation of sodium tellurite glasses

125Te static nuclear magnetic resonance (NMR) and 23Na and 125Te magic angle spinning (MAS) NMR have been used, in conjunction with X-ray diffraction, to examine the structure and crystallisation behaviour of glasses of composition xNa 2O·(1− x)TeO 2 ( 0.075 ⩽ x ⩽ 0.4 ). The MAS NMR 23Na spectra from the glasses are broad and featureless but shift by ∼+5 ppm with increased x , i.e. as the system becomes more ionic. The static 125Te NMR spectra show an increase in axial symmetry with increasing x, indicating a shift from predominantly [TeO 4] to [TeO 3] structural units. The 23Na and 125Te spectra from the crystallised samples have been fitted to obtain information on the sites in the metastable crystal phases, which are the first to form on heating and which are therefore more closely related to the glass structure than thermodynamically stable crystal phases. New sodium tellurite phases are reported, including a sodium stabilised, face centred cubic phase related to δ -TeO 2; a metastable form of Na 2Te 4O 9 containing 3 sodium and 4 tellurium sites; and a metastable form of Na 2Te 2O 5 containing 2 sodium sites. There is evidence of oxidation of Te IV to Te VI occurring in glasses with high values of x and, at x = 0.40 and 0.50 (outside the glass forming range), some sodium metatellurate (Na 2TeO 4) is formed at the same time as sodium metatellurite (Na 2TeO 3). The 125Te shift is very sensitive to environment within the sodium tellurite system, covering more than 320 ppm, with anisotropies varying from 640 to 1540 ppm. The lack of features in the 125Te spectra of the glass phases, combined with the large shift range and high but variable anisotropy, means than it is not possible to obtain a unique fit to any presumed species present. Furthermore, the chemical shift anisotropy parameters for three of the four Te sites in the Na 2Te 4O 9 phase are found to lie outside the range used for previous simulations of glass spectra.

Preparation and characterization of copper telluride thin films by modified chemical bath deposition (M-CBD) method

Copper telluride thin films were deposited using modified chemical method using copper(II) sulphate; pentahydrate [CuSO 4·5H 2O] and sodium tellurite [Na 2TeO 3] as cationic and anionic sources, respectively. Modified chemical method is based on the immersion of the substrate into separately placed cationic and anionic precursors. The preparative conditions such as concentration, pH, immersion time, immersion cycles, etc. were optimized to get good quality copper telluride thin films at room temperature. The films have been characterized for structural, compositional, optical and electrical transport properties by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDAX), Rutherford back scattering (RBS), optical absorption/transmission, electrical resistivity and thermoemf measurement techniques.

Microexplosions in tellurite glasses

Femtosecond laser pulses were used to produce localized damage in the bulk and near the surface of baseline, Al2O3-doped and La2O3-doped sodium tellurite glasses. Single or multiple laser pulses were non-linearly absorbed in the focal volume by the glass, leading to permanent changes in the material in the focal volume. These changes were caused by an explosive expansion of the ionized material in the focal volume into the surrounding material, i.e. a microexplosion. The writing of simple structures (periodic array of voxels, as well as lines) was demonstrated. The regions of microexplosion and writing were subsequently characterized using scanning electron microscopy (SEM), energy-dispersive spectrometry (EDS) and atomic force microscopy (AFM). Fingerprints of microexplosions (concentric lines within the region and a concentric ring outside the region), due to the shock wave generated during microexplosions, were evident. In the case of the baseline glass, no chemistry change was observed within the region of the microexplosion. However, Al2O3-doped and La2O3-doped glasses showed depletion of the dopant from the edge to the center of the region of the microexplosions, indicating a chemistry gradient within the regions. Interrogation of the bulk- and laser-treated regions using micro-Raman spectroscopy revealed no structural change due to the microexplosions and writing within these glasses.