Manganese(II)-Catalyzed and Clay-Minerals-Mediated Reduction of Chromium(VI) by Citrate

Sarkar, Binoy and Naidu, Ravi and Krishnamurti, Gummuluru S. R. and Megharaj, Mallavarapu (2013) Manganese(II)-Catalyzed and Clay-Minerals-Mediated Reduction of Chromium(VI) by Citrate. Environmental Science and Technology, 47 (23). pp. 13629-13636. ISSN 0013-936X

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Abstract

Unlike lower valent iron (Fe), the potential role of lower valent manganese (Mn) in the reduction of hexavalent chromium (Cr(VI)) in soil is poorly documented. In this study, we report that citrate along with Mn(II) and clay minerals (montmorillonite and kaolinite) reduce Cr(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) + Mn(II) (182.02 μM) + clay minerals (3% w/v) system in SDOC accounted for complete reduction of Cr(VI) (192.32 μM) in about 72 h at pH 4.9. In this system, citrate was the reductant, Mn(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 Cr(III). This study reveals the underlying mechanism of the Mn(II)-induced reduction of Cr(VI) by organic ligand in the presence of clay minerals under certain environmental conditions.

Item Type:
Journal Article
Journal or Publication Title:
Environmental Science and Technology
Uncontrolled Keywords:
/dk/atira/pure/subjectarea/asjc/1600
Subjects:
ID Code:
140938
Deposited By:
Deposited On:
31 Jan 2020 16:15
Refereed?:
Yes
Published?:
Published
Last Modified:
09 Sep 2020 06:42