Vitrificação de resíduos industriais contendo metais tóxicos: Análise da corrosão superficial após 10 anos de exposição à umidade do ar

Abstract

Vitrification of industrial waste containing transition metals has been widely studied as a means of mitigating harmful emissions to the environment. The chemical inertness of these materials is the key factor for their environmental safety. The chemical resistance was avaliated by hydrolytic, acid and alkali medium attack test that has been used for simulation of behavior along the time. However, there is a lack of studies that demonstrate the actual performance of such materials. Glass containing 10 to 50 Wt% of toxic metals (Cr, Ni, Cu, Zn) were prepared by the method of replacing cations modifiers for metals, having a chemical resistance and characterized evaluated by various techniques, proving the superior performance of samples containing between 30 and 40 wt% of transition metal oxides being the same or similar performance of commercial soda-lime glasses. After the initial characterization the glasses samples were exposed to the atmosphere, safe from bad weather during periods non less than 10 years at room temperature and in the shade in the region of São Paulo. In this study the samples were retested by SEM, XRD and FT-IR. Was observed the corrosion products formation in the samples with 10, 20 and 50 Wt% of metal oxide contained. The comparison with initial results to current characterizations (10 years later) showed consistent behavior with the behavior prediction obtained by the chemical resistance tests when the samples was prepared, i.e., samples containing between 30 and 40 Wt% of toxic metals was maintained the planned stability.