Determination of Sulfur Environments in Borosilicate Waste Glasses Using X-ray Absorption Near-Edge Spectroscopy
Document Type
Article
Publication Date
2004
Publication Title
Journal of Non-Crystalline Solids
Volume
333
First page number:
74
Last page number:
84
Abstract
Sulfur can be the waste-loading limiting constituent for vitrification of sulfur-bearing radioactive wastes due to low solubility in silicate melts. Methods to improve sulfur loading would benefit from improved understanding of the structural aspects of sulfur incorporation in borosilicate and other glasses. To this end, sulfur XANES spectra were collected for eight crystalline standards and twenty-four glasses, including borosilicate, phosphate, and borate compositions. Spectra for the standards show a systematic energy shift of the sulfur K-edge from 2469 to 2482 eV, as sulfur valence increases from 2- (in sulfides) to 6+ (in sulfates). Most crucible glasses investigated have simple edges near 2482 eV that indicate sulfur in the form of sulfate only. Other glasses, some synthesized under reducing conditions, have complicated edges, indicating sulfate, sulfite, and more reduced species that may include S, S–S doublets, or short polysulfide chains. Sulfide species (S2-) were not dominant in any of the samples over the range of redox conditions investigated. These results indicate that sulfur incorporation is considerably more complex than would be suggested by the conventional interpretation of the redox-dependence of sulfur solubility, which considers only sulfate and sulfide species. Raman data indicate that several of the glasses investigated are not homogeneous with regard to all sulfur species.
Keywords
Boron compounds; Glass; Silicates; Sulfate; Sulfur; X-ray Absorption Near Edge Structure
Disciplines
Analytical Chemistry | Atomic, Molecular and Optical Physics | Biological and Chemical Physics | Physical Chemistry
Language
English
Permissions
Use Find in Your Library, contact the author, or use interlibrary loan to garner a copy of the article. Publisher copyright policy allows author to archive post-print (author’s final manuscript). When post-print is available or publisher policy changes, the article will be deposited
Repository Citation
McKeown, D. A.,
Muller, I. S.,
Gan, H.,
Pegg, I. L.,
Stolte, W. C.
(2004).
Determination of Sulfur Environments in Borosilicate Waste Glasses Using X-ray Absorption Near-Edge Spectroscopy.
Journal of Non-Crystalline Solids, 333
74-84.