Thermal detoxification and bloating of chromium(VI) with bentonite

✍ Scribed by Y.-L. Wei; H.-F. Hsieh; Y.-S. Peng; J.-C. Yang; H. Paul Wang; C.-Y. Lin; W.-L. Shih; C.-C. Hsu

• Publisher: Elsevier Science
• Year: 2010
• Tongue: English
• Weight: 341 KB
• Volume: 619
• Category: Article
• ISSN: 0168-9002
• DOI: 10.1016/j.nima.2009.10.130

✦ Synopsis

This study stabilizes and bloats Cr(VI)-sorbed bentonite by heating at high temperature. Cr leaching decreases with increasing temperatures. Heating the sample at 1100 1C results in a non-detectable Cr concentration in the leachate, equivalent to a Cr leaching percent less than 0.001% (i.e., Cr TCLP concentration o 0.018 mg of Cr L À 1 of leachate). Morphology observed with a scanning electron microscopy indicates the occurrence of sintering of the sample heated at 1100 1C. The heated samples also show the occurrence of a vesicant process at 1100 1C. X-ray absorption spectroscopy results indicate that heating at 500 1C for 4 h can convert approximately 87% Cr(VI) into Cr(III) that is negligibly toxic; Cr 2 O 3 was detected to be the most abundant Cr species. After heating at higher temperatures, namely 900-1100 1C, almost all doped Cr(VI) is reduced to Cr(III) as inferred from the height of the pre-edge peak of XANES spectra and/or from XANES simulation.