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Hexavalent chromium release over time from a pyrolyzed Cr-bearing tannery sludge

Pyrolysis in an inert atmosphere is a widely applied route to convert tannery wastes into reusable materials. In the present study, the Cr(III) conversion into the toxic hexavalent form in the pyrolyzed tannery waste referred to as KEU was investigated. Ageing experiments and leaching tests demonstr...

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Detalles Bibliográficos
Autores principales: Ghezzi, Lisa, Mugnaioli, Enrico, Perchiazzi, Natale, Duce, Celia, Pelosi, Chiara, Zamponi, Erika, Pollastri, Simone, Campanella, Beatrice, Onor, Massimo, Abdellatief, Mahmoud, Franceschini, Fabrizio, Petrini, Riccardo
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Nature Publishing Group UK 2023
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10539330/
https://www.ncbi.nlm.nih.gov/pubmed/37770570
http://dx.doi.org/10.1038/s41598-023-43579-9
Descripción
Sumario:Pyrolysis in an inert atmosphere is a widely applied route to convert tannery wastes into reusable materials. In the present study, the Cr(III) conversion into the toxic hexavalent form in the pyrolyzed tannery waste referred to as KEU was investigated. Ageing experiments and leaching tests demonstrated that the Cr(III)–Cr(VI) inter-conversion occurs in the presence of air at ambient temperature, enhanced by wet environmental conditions. Microstructural analysis revealed that the Cr-primary mineral assemblage formed during pyrolysis (Cr-bearing srebrodolskite and Cr-magnetite spinel) destabilized upon spray water cooling in the last stage of the process. In the evolution from the higher to the lower temperature mineralogy, Cr is incorporated into newly formed CrOOH flakes which likely react in air forming extractable Cr(VI) species. This property transforms KEU from an inert waste to a hazardous material when exposed to ordinary ambient conditions.