Raman and IR spectroscopic investigation of As adsorbed on Mn3O4 magnetic composites

Raman and IR spectra were recorded of the As-loaded Mn3O4 magnetic composites obtained from the adsorption studies performed with As(III). XANES results for the composite after As(III) removal tests show that the As adsorbed is at the oxidized arsenic form, As(V). Monodentate and bidentate surface complexes are suggested for arsenic adsorption onto the composite (5–16 mg/g). Precipitation of manganese arsenate is observed for high As loading (35 mg/g).

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► Arsenic adsorption onto Mn3O4 magnetic composite.
► XANES shows that As(III) is oxidized to As(V).
► Raman and IR spectra of As loaded samples show peaks which indicate As(V) monodentate and bidentate complexes.
► Precipitation of manganese arsenate is observed for high As loading.