Oxidation of Cr(III) to Cr(VI) and Production of Mn(II) by Synthetic Manganese(IV) Oxide
| Autor: | Lauren Bocknek, Kaiyin Chen, Bruce Manning |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 2021 |
| Předmět: |
birnessite
Birnessite oxidation General Chemical Engineering Oxide chemistry.chemical_element dissolution 02 engineering and technology Manganese 010501 environmental sciences 01 natural sciences Redox Inorganic Chemistry Chromium chemistry.chemical_compound Spectrophotometry medicine General Materials Science chromium(VI) Fourier transform infrared spectroscopy manganese oxide 0105 earth and related environmental sciences Crystallography medicine.diagnostic_test Chemistry 021001 nanoscience & nanotechnology Condensed Matter Physics QD901-999 chromium 0210 nano-technology Stoichiometry Nuclear chemistry |
| Zdroj: | Crystals Volume 11 Issue 4 Crystals, Vol 11, Iss 443, p 443 (2021) |
| ISSN: | 2073-4352 |
| DOI: | 10.3390/cryst11040443 |
| Popis: | The heterogeneous oxidation of Cr(III) to Cr(VI), a toxic inorganic anion, by a synthetic birnessite (δ-MnO2) 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 δ-MnO2. 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 δ-MnO2 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 MnO2, forming a highly mobile and toxic groundwater contaminant. |
| Databáze: | OpenAIRE |
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