Hydrolysis of Tungsten(VI): Ultracentrifugation, Acidity Measurements, and Raman Spectra of Polytungstates

Aveston, J.

doi:10.1021/ic50017a012

Cited by 80 publications

(38 citation statements)

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“…The alpha‐helical protein in buffer A was spiked with tungsten from sodium tungstate (Na 2 WO 4 ) in buffer A to reach final tungsten concentrations of 100, 500, and 1000 ppm; with tungsten from tungsten pin extract in buffer A to reach final tungsten concentrations of 1, 10, 100, 500, and 1000 ppm; with tungsten from soluble WO 3 and H 2 WO 4 in buffer A to reach final tungsten concentrations of 1, 10, and 100 ppm and with tungsten from acidified Na 2 WO 4 in H 2 O to reach final tungsten concentrations of 1, 10, 100, and 1000 ppm. It has been shown that Na 2 WO 4 forms polytungstate anions at lower pHs 9–13. To assess whether the polytungstate anions rather than Na 2 WO 4 contribute to the protein aggregation, the spiking studies were also carried out with acidified Na 2 WO 4 .…”

Section: Methodsmentioning

confidence: 99%

Tungsten-induced protein aggregation: Solution behavior

Jiang

Nashed-Samuel

et al. 2009

Journal of Pharmaceutical Sciences

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Section: Methodsmentioning

confidence: 99%

Tungsten-induced protein aggregation: Solution behavior

Jiang

Nashed-Samuel

et al. 2009

Journal of Pharmaceutical Sciences

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“…In the VIB group, the tendency for polymerization increases with increasing atomic number, so that occurrence of polymeric forms of tungstate may be more common than molybdate for equivalent conditions [11]. Tungstate speciation has been studied by several researchers with 187 W nuclear magnetic resonance (NMR) spectroscopy, electrospray ionization mass spectrometry (ESI-MS), and Raman spectroscopy [4,5,13,14]. These studies have shown that general trends of tungsten polymerization are known under acidic conditions, yet the mechanisms are still not completely understood.…”

Section: Introductionmentioning

confidence: 99%

Tungstate sorption mechanisms on boehmite: Systematic uptake studies and X-ray absorption spectroscopy analysis

Hur

Reeder

2016

Journal of Colloid and Interface Science

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Mechanisms of tungstate sorption on the mineral boehmite (γ-AlOOH) were studied using batch uptake experiments and X-ray absorption spectroscopy. Batch uptake experiments over the pH range 4-8 and [W]=50-2000 μM show typical oxyanion behavior, and isotherm experiments reveal continued uptake with increasing tungstate concentration without any clear uptake maximum. Desorption experiments showed that sorption is irreversible at pH 4 and partly reversible at pH 8. Tungsten L1- and L3-edge XANES spectroscopy indicates that all sorbed tungstates are octahedrally coordinated, even though the dominant solution species at pH 8 is a tetrahedral monotungstate. Tungsten L3-edge EXAFS analysis shows that sorbed tungstate occurs as polymeric form(s), as indicated by the presence of corner- and edge-sharing of distorted tungstate octahedra. The occurrence of polymeric tungstate on the surface at pH 8 indicates that sorption is accompanied by polymerization and a coordination change from tetrahedral (in solution) to distorted octahedral (on the surface). The strong tendency for tungstate polymerization on boehmite can explain the continued uptake without an apparent maximum in sorption, and the limited desorption behavior. Our results provide the basis for a predictive model of tungstate uptake by boehmite, which can be important for understanding tungstate mobility, toxicity, and bioavailability.

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“…For this purpose, a system of equations was solved using adopted Maple6 (Waterloo Maple Software and University of Waterloo). The set of equations was based on: (i) the equilibrium constants for all compounds added to or formed in the solutions: acids deprotonation, 33,34 iron hydrolysis, 35,36 polymerization of tungstate, 37 glycolate complexes with Fe and W [38][39][40][41] and metal complexes with citrate; [42][43][44][45] (ii) the mass balance equations…”

Section: Methodsmentioning

confidence: 99%

Fe (III)-Based Ammonia-Free Bath for Electrodeposition of Fe-W Alloys

Nicolenco

Цынцару

Cesiulis

2017

J. Electrochem. Soc.

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Electrodeposited Fe-W alloys are the subject of extensive studies to be applied in versatile engineering applications, and many solutions based on Fe(II) complexes are described for their deposition. However, in aqueous solutions containing dissolved oxygen, Fe(II) compounds are unstable thermodynamically and tend to oxidize to Fe(III) state that decreases the sustainability of the baths. The aim of the present study was to develop an environment-friendly and thermodynamically stable Fe(III)-based electrolyte for electrodeposition of Fe-W alloys with tunable composition. It was found that: (i) concurrent use of two complexing agents as citric and glycolic acids stabilizes Fe(III)-based bath in neutral and weak alkaline medium (no precipitates are formed); (ii) the current efficiency of the process can reach up to 60-70%, which has never been reported before for Fe-W alloys electrodeposition; (iii) nanocrystalline Fe-W coatings containing 11-24 at.% of W can be obtained from Fe(III)-based glycolate-citrate bath at temperature range 20-65 • C. The increase in tungsten content in the alloy resulted in decreased grain size up to < 5 nm; (iv) smooth, free of cracks and having deposition rates up to 0.18 μm/cm 1 alloys are successfully electrodeposited at elevated temperatures from elaborated glycolate-citrate electrolyte.

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Hydrolysis of Tungsten(VI): Ultracentrifugation, Acidity Measurements, and Raman Spectra of Polytungstates

Cited by 80 publications

References 0 publications

Tungsten-induced protein aggregation: Solution behavior

Tungsten-induced protein aggregation: Solution behavior

Tungstate sorption mechanisms on boehmite: Systematic uptake studies and X-ray absorption spectroscopy analysis

Fe (III)-Based Ammonia-Free Bath for Electrodeposition of Fe-W Alloys

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