2 research outputs found
Manganese(II)-Catalyzed and Clay-Minerals-Mediated Reduction of Chromium(VI) by Citrate
Unlike lower valent iron (Fe), the
potential role of lower valent
manganese (Mn) in the reduction of hexavalent chromium (CrÂ(VI)) in
soil is poorly documented. In this study, we report that citrate along
with MnÂ(II) and clay minerals (montmorillonite and kaolinite) reduce
CrÂ(VI) both in aqueous phase and in the presence of dissolved organic
carbon (SDOC) extracted from a forest soil. The reduction was favorable
at acidic pH (up to pH 5) and followed the pseudo-first-order kinetic
model. The citrate (10 mM) + MnÂ(II) (182.02 μM) + clay minerals
(3% w/v) system in SDOC accounted for complete reduction of CrÂ(VI)
(192.32 μM) in about 72 h at pH 4.9. In this system, citrate
was the reductant, MnÂ(II) was a catalyst, and the clay minerals acted
as an accelerator for both the reductant and catalyst. The clay minerals
also serve as a sink for CrÂ(III). This study reveals the underlying
mechanism of the MnÂ(II)-induced reduction of CrÂ(VI) by organic ligand
in the presence of clay minerals under certain environmental conditions