Oxidation of Cr(III) to Cr(VI) and Production of Mn(II) by Synthetic Manganese(IV) Oxide
The heterogeneous oxidation of Cr(III) to Cr(VI), a toxic inorganic anion, by a synthetic birnessite (<i>δ</i>-MnO<sub>2</sub>) was investigated in batch reactions using a combination of analytical techniques including UV–Vis spectrophotometry, microwave plasma–atomic emissio...
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MDPI AG
2021-04-01
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| Series: | Crystals |
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| Online Access: | https://www.mdpi.com/2073-4352/11/4/443 |
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| author | Kaiyin Chen Lauren Bocknek Bruce Manning |
| author_facet | Kaiyin Chen Lauren Bocknek Bruce Manning |
| author_sort | Kaiyin Chen |
| collection | DOAJ |
| description | The heterogeneous oxidation of Cr(III) to Cr(VI), a toxic inorganic anion, by a synthetic birnessite (<i>δ</i>-MnO<sub>2</sub>) was investigated in batch reactions using a combination of analytical techniques including UV–Vis spectrophotometry, microwave plasma–atomic emission spectrometry, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared spectroscopy (FTIR), to evaluate both the solution speciation of Cr(III)/Cr(VI) and the surface of the reacted <i>δ</i>-MnO<sub>2</sub>. The formation of dissolved Mn(II) was determined during the batch reactions to evaluate the extent and stoichiometry of the Cr(III) oxidation reaction. A stoichiometric 3:2 Mn(II):Cr(VI) molar relationship was observed in the reaction products. The reductive dissolution of the <i>δ</i>-MnO<sub>2</sub> by Cr(III) resulted in a surface alteration from the conversion of Mn(IV) oxide to reduced Mn(II) and Mn(III) hydroxides. The results of this investigation show that naturally occurring Cr(III) will readily oxidize to Cr(VI) when it comes in contact with MnO<sub>2,</sub> forming a highly mobile and toxic groundwater contaminant. |
| first_indexed | 2024-03-10T12:10:46Z |
| format | Article |
| id | doaj.art-91ec5229d8e64cf2bed59ac9545573e9 |
| institution | Directory Open Access Journal |
| issn | 2073-4352 |
| language | English |
| last_indexed | 2024-03-10T12:10:46Z |
| publishDate | 2021-04-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Crystals |
| spelling | doaj.art-91ec5229d8e64cf2bed59ac9545573e92023-11-21T16:14:18ZengMDPI AGCrystals2073-43522021-04-0111444310.3390/cryst11040443Oxidation of Cr(III) to Cr(VI) and Production of Mn(II) by Synthetic Manganese(IV) OxideKaiyin Chen0Lauren Bocknek1Bruce Manning2Department of Chemistry and Biochemistry, San Francisco State University, San Francisco, CA 94132, USADepartment of Chemistry and Biochemistry, San Francisco State University, San Francisco, CA 94132, USADepartment of Chemistry and Biochemistry, San Francisco State University, San Francisco, CA 94132, USAThe heterogeneous oxidation of Cr(III) to Cr(VI), a toxic inorganic anion, by a synthetic birnessite (<i>δ</i>-MnO<sub>2</sub>) was investigated in batch reactions using a combination of analytical techniques including UV–Vis spectrophotometry, microwave plasma–atomic emission spectrometry, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared spectroscopy (FTIR), to evaluate both the solution speciation of Cr(III)/Cr(VI) and the surface of the reacted <i>δ</i>-MnO<sub>2</sub>. The formation of dissolved Mn(II) was determined during the batch reactions to evaluate the extent and stoichiometry of the Cr(III) oxidation reaction. A stoichiometric 3:2 Mn(II):Cr(VI) molar relationship was observed in the reaction products. The reductive dissolution of the <i>δ</i>-MnO<sub>2</sub> by Cr(III) resulted in a surface alteration from the conversion of Mn(IV) oxide to reduced Mn(II) and Mn(III) hydroxides. The results of this investigation show that naturally occurring Cr(III) will readily oxidize to Cr(VI) when it comes in contact with MnO<sub>2,</sub> forming a highly mobile and toxic groundwater contaminant.https://www.mdpi.com/2073-4352/11/4/443chromiumchromium(VI)oxidationmanganese oxidebirnessitedissolution |
| spellingShingle | Kaiyin Chen Lauren Bocknek Bruce Manning Oxidation of Cr(III) to Cr(VI) and Production of Mn(II) by Synthetic Manganese(IV) Oxide Crystals chromium chromium(VI) oxidation manganese oxide birnessite dissolution |
| title | Oxidation of Cr(III) to Cr(VI) and Production of Mn(II) by Synthetic Manganese(IV) Oxide |
| title_full | Oxidation of Cr(III) to Cr(VI) and Production of Mn(II) by Synthetic Manganese(IV) Oxide |
| title_fullStr | Oxidation of Cr(III) to Cr(VI) and Production of Mn(II) by Synthetic Manganese(IV) Oxide |
| title_full_unstemmed | Oxidation of Cr(III) to Cr(VI) and Production of Mn(II) by Synthetic Manganese(IV) Oxide |
| title_short | Oxidation of Cr(III) to Cr(VI) and Production of Mn(II) by Synthetic Manganese(IV) Oxide |
| title_sort | oxidation of cr iii to cr vi and production of mn ii by synthetic manganese iv oxide |
| topic | chromium chromium(VI) oxidation manganese oxide birnessite dissolution |
| url | https://www.mdpi.com/2073-4352/11/4/443 |
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