Technical NoteIron species in layered clay: Efficient electron shuttles for simultaneous conversion of dyes and Cr(VI)

•Iron bearing clays are efficient catalysts for co-conversion of Cr(VI) and dyes.•Molecular oxygen has an insignificant effect on photosensitized reduction of Cr(VI).•These iron-bearing clays are stable and reusable for Cr(VI) reduction.

The simultaneous reduction of Chromium(VI) (Cr(VI)) and oxidation of cationic dyes in dispersions of Montmorillonite K10 (MK10) were examined under visible irradiation (λ > 420 nm). The iron species (i.e. iron oxides, structural iron and exchangeable interlayer iron) in layered clays are active for catalytically reducing Cr(VI) by using Malachite green (MG) and Rhodamine B (RhB) as the electron donors. Molecular oxygen does not have a significant effect on clay-catalyzed Cr(VI) reduction, but is important for oxidative degradation of dye pollutants. MK10 catalysts are stable and reusable, and are therefore considered as a promising naturally-abundant material for decontamination of dye and heavy metals.