Vitrification of urban soil contamination by hexavalent chromium

• Published in: Journal of geochemical exploration Vol. 174; pp. 132 - 139
• Main Authors: Ballesteros, S., Rincón, J.Ma, Rincón-Mora, B., Jordán, M.M.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01-03-2017
• Subjects: Hexavalent chromium; Mexico; Soil remediation; Vitrification; Hexavalent chromium; Soil remediation; Mexico; Vitrification
• ISSN: 0375-6742; 1879-1689
• DOI: 10.1016/j.gexplo.2016.07.011

This research describes the characteristics, formation mechanisms, and leaching of Cr6+ wastes that are contaminating a Mexican urban soil. By means of a vitrification process, a method has been proposed that transforms Cr6+ to Cr3+ and achieves effective immobilization of this highly toxic industrial waste affecting an urban area. By various physicochemical and microstructure characterization techniques, such as XRD, DTA, and SEM/EDS, carrying out complete characterization of these new materials was possible. The final vitrified or glassy products of silicate composition lead to a glass ceramic material that is environmentally very stable, showing high chemical and mechanical stability where all Cr6+ was reduced to Cr3+ in the residual glass network, as well as other chromium oxidation states confined in the crystalline phases formed in the final glass-ceramic. The leaching tests on samples stabilized by vitrification have shown that the release of ions from the structure of these new materials was negligible, yielding values <0.5mg/l with respect to current international and domestic environmental regulations. The final glass-ceramics obtained by vitrification and controlled crystallization showed adequate mechanical resistance properties.
•A method for remediation of a polluted soil has been adapted and developed.•Vitrification is a powerful and reliable tool for immobilizing Cr+6 in soils.•The Cr+6 contents in glass/glass-ceramics were <0.22mg/kg.•TGA/DTA provides date about thermal stability and phase transformations.