Namgung, Seonyi Kwon, Man Jae Qafoku, Nikolla P. Lee, Giehyeon 2024-01-20T09:01:03Z 2024-01-20T09:01:03Z 2021-09-02 2014-09-16 0013-936X https://pubs.kist.re.kr/handle/201004/126339 We examined the feasibility of Cr(OH)(3)(s) oxidation mediated by surface catalyzed Mn(II) oxidation under common groundwater pH conditions as a potential pathway of natural Cr(VI) contaminations. Dissolved Mn(II) (50 ?M) was reacted with or without synthesized Cr(OH)(3)(s) (1.0 g/L) at pH 7.0-9.0 under oxic or anoxic conditions. Homogeneous Mn(II) oxidation by dissolved O2 was not observed at pH ? 8.0 for 50 days. At pH 9.0, by contrast, dissolved Mn(II) was completely removed within 8 days and precipitated as hausmannite. When Cr(OH)(3)(s) was present, this solid was oxidized and released substantial amounts of Cr(VI) as dissolved Mn(II) was added into the suspension at pH ? 8.0 under oxic conditions. Production of Cr(VI) was attributed to Cr(OH)(3)(s) oxidation by a newly formed Mn oxide via Mn(II) oxidation catalyzed on Cr(OH)(3)(s) surface. XANES results indicated that this surface-catalyzed Mn(II) oxidation produced a mixed valence Mn(III/IV) solid phase. Our results suggest that toxic Cr(VI) can be naturally produced via Cr(OH)(3)(s) oxidation coupled with the oxidation of dissolved Mn(II). In addition, this study evokes the potential environmental hazard of sparingly soluble Cr(OH)(3)(s), which has been considered the most common and a stable remediation product of Cr(VI) contamination. English American Chemical Society BIOGENIC MN-OXIDES SP STRAIN SG-1 MANGANESE(II) OXIDATION MARINE BACILLUS CHROMIUM(III) OXIDATION HEXAVALENT CHROMIUM REDUCTIVE TRANSFORMATION AQUEOUS MN(II) NATURAL-WATERS KINETICS Cr(OH)(3)(s) Oxidation Induced by Surface Catalyzed Mn(II) Oxidation Article 10.1021/es503018u 1 Environmental Science & Technology, v.48, no.18, pp.10760 - 10768 Environmental Science & Technology 48 18 10760 10768 scie scopus 000341801500029 2-s2.0-84924778226 Engineering, Environmental Environmental Sciences Engineering Environmental Sciences & Ecology Article BIOGENIC MN-OXIDES SP STRAIN SG-1 MANGANESE(II) OXIDATION MARINE BACILLUS CHROMIUM(III) OXIDATION HEXAVALENT CHROMIUM REDUCTIVE TRANSFORMATION AQUEOUS MN(II) NATURAL-WATERS KINETICS