Vitrification of urban soil contamination by hexavalent chromium

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 < 0.5 mg/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.