![Application of the Rietveld method to assess chromium(VI) speciation in chromite ore processing residue [An article from: Journal of Hazardous Materials]](https://www.ebooknetworking.net/books/B00/0PD/bigB000PDTYU4.jpg)
Application of the Rietveld method to assess chromium(VI) speciation in chromite ore processing residue [An article from: Journal of Hazardous Materials]
Book Details
Author(s)M. Chrysochoou, D. Dermatas
PublisherElsevier
ISBN / ASINB000PDTYU4
ISBN-13978B000PDTYU2
MarketplaceCanada 🇨🇦
Description
This digital document is a journal article from Journal of Hazardous Materials, published by Elsevier in 2007. The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser.
Description:
The Rietveld method allows the quantification of crystalline phases and amorphous material identified by X-ray powder diffraction (XRPD) and other diffraction methods. The method assists in determining the speciation of contaminants in solid matrices both qualitatively and quantitatively in a statistically defensible approach, as it does not focus on a microscale. Rietveld was applied to chromite ore processing residue (COPR), a cementitious waste containing hexavalent chromium. Calcium aluminum chromium oxide hydrates (CACs) were the crystalline phases identified by XRPD that bind Cr^6^+ in COPR according to their chemical formula. Rietveld quantification, combined with mass balances on Cr^6^+, showed that CACs may bind Cr^6^+ in variable percentages, ranging from 25% to 85%. Analysis of duplicate samples showed that material variability is the predominant factor of uncertainty in evaluating the role of CACs in Cr^6^+ speciation, provided that a consistent quantification strategy is pursued. The choice of strategy was performed on the basis of the pertinent literature, preliminary analyses of the equipment and the software settings, and mass balances. The correlation between the average CAC-bound Cr^6^+ concentration and the total Cr^6^+ for five samples (R^2=0.94), extracted from different zones and soil borings, suggests that CACs are a primary sink for Cr^6^+ in COPR.
Description:
The Rietveld method allows the quantification of crystalline phases and amorphous material identified by X-ray powder diffraction (XRPD) and other diffraction methods. The method assists in determining the speciation of contaminants in solid matrices both qualitatively and quantitatively in a statistically defensible approach, as it does not focus on a microscale. Rietveld was applied to chromite ore processing residue (COPR), a cementitious waste containing hexavalent chromium. Calcium aluminum chromium oxide hydrates (CACs) were the crystalline phases identified by XRPD that bind Cr^6^+ in COPR according to their chemical formula. Rietveld quantification, combined with mass balances on Cr^6^+, showed that CACs may bind Cr^6^+ in variable percentages, ranging from 25% to 85%. Analysis of duplicate samples showed that material variability is the predominant factor of uncertainty in evaluating the role of CACs in Cr^6^+ speciation, provided that a consistent quantification strategy is pursued. The choice of strategy was performed on the basis of the pertinent literature, preliminary analyses of the equipment and the software settings, and mass balances. The correlation between the average CAC-bound Cr^6^+ concentration and the total Cr^6^+ for five samples (R^2=0.94), extracted from different zones and soil borings, suggests that CACs are a primary sink for Cr^6^+ in COPR.
