Tetrahedral Tellurate

Konaka, Saki; Ozawa, Yoshiki; Yagasaki, Atsushi

doi:10.1021/ic701578p

Cited by 20 publications

(18 citation statements)

References 12 publications

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“…Complex and inconsistent stoichiometric associations with other trace elements (especially Pb, Bi and Sb) were observed, but could not be identified as specific mineral phases. The inconsistent stoichiometry of these phases suggested intergrown mineral phases, coprecipitation or Te substitution, such as Te substitution into sulfate or sulfosalt minerals that have been previously postulated or reported (George et al 2017;Konaka et al 2008;Trudu and Knittel 1998). The Feature Sizing software poorly identified and quantified S in the presence of Bi and Pb, which complicated the identification of sulfosalt minerals.…”

Section: Grain-scale Investigation Of Telluriummentioning

confidence: 99%

Surficial geochemistry and bioaccessibility of tellurium in semiarid mine tailings

Hayes

Ramos

2019

Environ. Chem.

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Environmental contextTellurium can be more toxic than arsenic, but its fate in the surficial environment is poorly understood. We studied tellurium behaviour in semiarid mine tailings and found that most tellurium is associated with iron (oxy)hydroxides as tellurate (TeVI), the less toxic oxidation state. Iron (oxy)hydroxides are likely to control the fate of Te in the surficial environment and may effectively sequester Te oxyanions released by oxidative weathering. AbstractTellurium (Te) is a critical element owing to its use in solar technology. However, some forms are highly toxic. Few studies have examined Te behaviour in the surficial environment, thus little is known about its potential human and environmental health impacts. This study characterises two physicochemically distinct Te-enriched mine tailings piles (big and flat tailings) deposited by historic gold (Au) mining in the semiarid Delamar mining district, Nevada, USA. The big tailings are characterised by smaller particle size and higher concentrations of potentially toxic elements (up to 290mgTekg−1), which are enriched at the tailings surface. In contrast, the flat tailings have larger particle size and properties that are relatively invariant with depth. Based on the sulfate to sulfide ratio, the tailings were determined to be sulfate dominated, which suggested a high degree of weathering, although the flat tailings did contain significant amounts of sulfides (~40%). Tellurium X-ray absorption spectroscopy of the big tailings indicates that tellurate, the less toxic Te species, is the principal form of Te. Electron microscopy indicates that most of the Te present at the site is associated with iron (oxy)hydroxides, and sometimes with other potentially toxic elements, especially lead and antimony. Physiologically-based extraction tests indicate that substantially more Te is solubilised in synthetic stomach fluids than in lung fluids, with gastric bioaccessibility ranging from 13 to 31% of total Te. This points to low to medium bioaccessibility, which is common for iron (oxy)hydroxide-associated elements. Together, these results represent a preliminary assessment of Te surficial behaviour in a semiarid environment and indicate that Te in these tailings represent a moderate health concern.

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Section: Grain-scale Investigation Of Telluriummentioning

confidence: 99%

Surficial geochemistry and bioaccessibility of tellurium in semiarid mine tailings

Hayes

Ramos

2019

Environ. Chem.

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“…Tellurate can heterogenize isopolyvanadate such as decavanadate [97], or more relevant in the present context, can form chain structures [98,99] with V x O y dimers. The fact that such structures exist as quite stable materials (accessible through hydrothermal synthesis) qualifies the structural motifs as low-energy alternatives for the termination of the complex M1 structure.…”

Section: Size and Functions Of Active Sitesmentioning

confidence: 99%

Active Sites for Propane Oxidation: Some Generic Considerations

Schlögl

2011

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Based on experimental observations about structure and dynamics of the reactive surface of the M1 phase some considerations are made about the nature and size of active sites. In analyzing the stoichiometry of the reactions following activation of propane it occurs that for dehydrogenation small sites are desirable being just sufficient to re-activate oxygen without kinetic hindrance. For deeper oxidation to acrylic acid (AA) the sites should be larger to accommodate all redox equivalents and oxygen species required for one transformation. A qualitative model for size and composition of the active site is made. It is likely that the active site consists on a VxOy species of strictly 2-D nature. This follows the structural suggestion for the active site on the a-b-plane of the M1 structure. The role of Te in moderating the active site is discussed. The suggestions are discussed in comparing requirements for oxidative dehydrogenation of propane (ODP) with those for AA synthesis.

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“…The participation of tellurate and tellurite as heteroanions in POM chemistry is reasonably well known: tellurate is employed in the formation of the Anderson‐type cluster {Te VI M 6 }(M=Mo or W)16, 17 and tellurite in the {Te IV W 9 } building blocks that form a variety of metal complexes, such as [Te 2 W 18 Cu 3 O 66 (H 2 O) 3 ] 10− , [Fe 4 (H 2 O) 10 (TeW 9 O 33 ) 2 ] 4− , and [M 3 (H 2 O) 8 (WO 2 )(TeW 9 O 33 ) 2 ] n − (M=V IV , Co II , Zn II , or Ni II ) 18. 19 However, to our knowledge, compounds 1 , 1′ , 2 , and 3 represent the first examples of tellurate and tellurite embedded within the Dawson‐type {W 18 O 54 } matrix, and thus offer the potential to develop new chemical and physical properties derived from the well‐known conventional Dawson cluster structure type.…”

Section: Methodsmentioning

confidence: 99%

Discovery of Heteroatom‐“Embedded” Te⊂{W₁₈O₅₄} Nanofunctional Polyoxometalates by Use of Cryospray Mass Spectrometry

et al. 2009

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Das Cryo‐Spiel: Die hier beschriebenen nanofunktionellen Cluster mit eingebettetem Heteroatom enthalten eine [TeVIO6]6−‐Spezies in einem {W18O54}‐Käfig. Die tellurhaltige Spezies aktiviert nicht nur die {W18O54}‐Clusteroberfläche für die Bildung größerer nanoskaliger Strukturen wie [H10TeVI2W58O198]26−, sondern sie geht auch im Innern des Clusters eine Redoxreaktion von [TeVIO6]6− zu [TeIVO3]2− ein.

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Tetrahedral Tellurate

Cited by 20 publications

References 12 publications

Surficial geochemistry and bioaccessibility of tellurium in semiarid mine tailings

Surficial geochemistry and bioaccessibility of tellurium in semiarid mine tailings

Active Sites for Propane Oxidation: Some Generic Considerations

Discovery of Heteroatom‐“Embedded” Te⊂{W₁₈O₅₄} Nanofunctional Polyoxometalates by Use of Cryospray Mass Spectrometry

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Tetrahedral Tellurate

Cited by 20 publications

References 12 publications

Surficial geochemistry and bioaccessibility of tellurium in semiarid mine tailings

Surficial geochemistry and bioaccessibility of tellurium in semiarid mine tailings

Active Sites for Propane Oxidation: Some Generic Considerations

Discovery of Heteroatom‐“Embedded” Te⊂{W18O54} Nanofunctional Polyoxometalates by Use of Cryospray Mass Spectrometry

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Discovery of Heteroatom‐“Embedded” Te⊂{W₁₈O₅₄} Nanofunctional Polyoxometalates by Use of Cryospray Mass Spectrometry