X-ray absorption studies of vanadium valence and local environment in borosilicate waste glasses using vanadium sulfide, silicate, and oxide standards

McKeown, David A.; Muller, Isabelle S.; Matlack, Keith S.; Pegg, Ian L.

doi:10.1016/s0022-3093(02)00945-6

Cited by 53 publications

(45 citation statements)

References 14 publications

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“…The V EXAFS data and fitting results for the standards vanadinite and cavansite, are similar to those presented earlier [2] (Fig. 4a and b).…”

Section: Vanadium Exafssupporting

confidence: 87%

“…1b and 2b). In general, the V XANES features do not change significantly from the oxidized parent glass to the most reduced glasses, as observed earlier for borosilicate glasses [2]. However, Cr XANES show large variations as these melts are exposed to longer bubbling times (Fig.…”

Section: Vanadium and Chromium Xanes Trends Versus Glass Chemistrysupporting

confidence: 80%

“…5a-d). Therefore, V is present mostly within V 5+ O 4 tetrahedra in these two glass series, as seen earlier for other borosilicate glasses [2].…”

Section: Vanadium Exafssupporting

confidence: 79%

“…Cr EXAFS data were also collected for three glasses from the more Cr-rich Z10-G-60C and Q10-G-136D series, which spanned one glass series from the oxidized parent glass to the most reduced glass where the corresponding melt was exposed to the longest bubbling time. V and Cr environments have been characterized in silicate and borosilicate glasses [2][3][4][5][6][7][8] [4][5][6], but can also be seen as Cr 2+ [7].…”

Section: Contents Lists Available At Sciencedirectmentioning

confidence: 99%

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Vanadium and chromium redox behavior in borosilicate nuclear waste glasses

McKeown

Muller

Gan

et al. 2011

Journal of Non-Crystalline Solids

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X-ray absorption spectroscopy (XAS) was used to characterize vanadium (V) and chromium (Cr) environments in low activity nuclear waste (LAW) glasses synthesized under a variety of redox conditions. V 2 O 5 was added to the melt to improve sulfur incorporation from the waste; however, at sufficiently high concentrations, V increased melt foaming, which lowered melt processing rates. Foaming may be reduced by varying the redox conditions of the melt, while small amounts of Cr are added to reduce melter refractory corrosion. Three parent glasses were studied, where CO-CO 2 mixtures were bubbled through the corresponding melt for increasing time intervals so that a series of redox-adjusted-glasses was synthesized from each parent glass. XAS data indicated that V and Cr behaviors are significantly different in these glasses with respect to the cumulative gas bubbling times: V 4+ /V total ranges from 8 to 35%, while Cr 3+ /Cr total can range from 15 to 100% and even to population distributions including Cr 2+. As Nacontent decreased, V, and especially, Cr became more reduced, when comparing equivalent glasses within a series. The Na-poor glass series show possible redox coupling between V and Cr, where V 4+ populations increase after initial bubbling, but as bubbling time increases, V 4+ populations drop to near the level of the parent glass, while Cr becomes more reduced to the point of having increasing Cr 2+ populations.

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“…The V EXAFS data and fitting results for the standards vanadinite and cavansite, are similar to those presented earlier [2] (Fig. 4a and b).…”

Section: Vanadium Exafssupporting

confidence: 87%

Section: Vanadium and Chromium Xanes Trends Versus Glass Chemistrysupporting

confidence: 80%

“…5a-d). Therefore, V is present mostly within V 5+ O 4 tetrahedra in these two glass series, as seen earlier for other borosilicate glasses [2].…”

Section: Vanadium Exafssupporting

confidence: 79%

Section: Contents Lists Available At Sciencedirectmentioning

confidence: 99%

See 2 more Smart Citations

Vanadium and chromium redox behavior in borosilicate nuclear waste glasses

McKeown

Muller

Gan

et al. 2011

Journal of Non-Crystalline Solids

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show abstract

“…With the addition of CaO and/or V 2 O 5 to Frit 320 4 , Frits 447, 448, and 449 were developed. Recent studies have suggested that CaO and V 2 O 5 additions to borosilicate formulations improve sulfur solubility in the melt (Stefanovsky and Lifanov, 1990;McKeown et al, 2002;Vienna et al, 2002). With the 1100-canister, 1 st transfer composition for SB4 (from Lilliston, 2005), the sealed-crucible studies with Frits 447, 448, and 449 showed the frits enhance the SO 4 = solubility for SB4 -all crucibles were clear of the "yellow" up to 0.7 wt% SO 4 = .…”

Section: Discussionmentioning

confidence: 99%