Reductive transformation of birnessite and the mobility of co-associated antimony.
J Hazard Mater
; 404(Pt B): 124227, 2021 02 15.
Article
em En
| MEDLINE
| ID: mdl-33086181
ABSTRACT
Manganese (Mn) oxide minerals, such as birnessite, are thought to play an important role in affecting the mobility and fate of antimony (Sb) in the environment. In this study, we investigate Sb partitioning and speciation during anoxic incubation of Sb(V)-coprecipitated birnessite in the presence and absence of Mn(II)aq at pH 5.5 and 7.5. Antimony K-edge XANES spectroscopy revealed that Sb(V) persisted as the only solid-phase Sb species for all experimental treatments. Manganese K-edge EXAFS and XRD results showed that, in the absence of Mn(II), the Sb(V)-bearing birnessite underwent no detectable mineralogical transformation during 7 days. In contrast, the addition of 10â¯mM Mn(II) at pH 7.5 induced relatively rapid (within 24â¯h) transformation of birnessite to manganite (~93%) and hausmannite (~7%). Importantly, no detectable Sb was measured in the aqueous phase for this treatment (compared with up to â¼90 µmol L-1 Sb in the corresponding Mn(II)-free treatment). At pH 5.5 , birnessite reacted with 10â¯mM Mn(II)aq displayed no detectable mineralogical transformation, yet had substantially increased Sb retention in the solid phase, relative to the corresponding Mn(II)-free treatment. These findings suggest that the Mn(II)-induced transformation and recrystallization of birnessite can exert an important control on the mobility of co-associated Sb.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Tipo de estudo:
Risk_factors_studies
Idioma:
En
Revista:
J Hazard Mater
Ano de publicação:
2021
Tipo de documento:
Article