Manganese Valence in Oxides Formed from in Situ Chemical Oxidation of TCE by KMnO4

详细信息    查看全文

• 作者：Diana B. Loomer ; Tom A. Al ; Vernon J. Banks ; Beth L. Parker ; K. Ulrich Mayer
• 刊名：Environmental Science & Technology
• 出版年：2010
• 出版时间：August 1, 2010
• 年：2010
• 卷：44
• 期：15
• 页码：5934-5939
• 全文大小：240K
• 年卷期：v.44,no.15(August 1, 2010)
• ISSN：1520-5851

文摘

Batch and column experiments designed to simulate in situ chemical oxidation (ISCO) in a sand aquifer were conducted to create Mn-oxides (MnO_x) by oxidation of trichloroethylene (TCE) with permanganate (MnO₄⁻). Electron energy-loss spectroscopy (EELS) and X-ray photoelectron spectroscopy (XPS) were used to quantify Mn valence in the oxides. The valence of Mn in the MnO_x generated in near-source ISCO conditions was 2.2 and 2.3 when formed at low (<3) and neutral (6−7) pH conditions, respectively. There is no significant difference between these values. Valence was found to be sensitive to the preparation method and to aging. When formed in the presence of excess MnO₄⁻, or aged for 3 months, Mn valence ranged from 2.5 to 3.6. Aging in a lower pH environment inhibited Mn oxidation. The EELS and XPS methods provided similar results, but there was a slight bias to higher values for XPS. This work demonstrates that MnO_2(s) may not be the main product of MnO₄⁻ reaction with chlorinated solvents as is commonly assumed and that the efficiency of ISCO treatment may be greater than previously known.