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CHROMIUM(III) OXIDATION BY THREE POORLY-CRYSTALLINE MANGANESE(IV) OXIDES 1. CHROMIUM(III)-OXIDIZING CAPACITY.
MedLine Citation:
PMID:  23050871     Owner:  NLM     Status:  Publisher    
Abstract/OtherAbstract:
The Cr(III)-oxidizing capacity of three layered poorly-crystalline Mn(IV)O2 phases, i.e. δ-MnO2, Random Stacked Birnessite (RSB), and Acid Birnessite (AB), was determined in real-time and in-situ, using Quick X-ray Absorption Fine Structure Spectroscopy (Q-XAFS). The results obtained with this technique, which allows the measurement of the total amount of Cr(VI) produced in the system, indicated that the Cr(III) oxidation reaction had ceased between 30 minutes and 1 hour under most experimental conditions. However, this cessation was not observed with a traditional batch technique, which only allows the measurement of Cr(VI) present in solution and thus neglects the amount of Cr(VI) that may be sorbed to Mn(IV)O2. This study also demonstrated that the Mn(IV)O2 phase oxidizing the highest amount of Cr(III), which is positively charged in solution, was the mineral featuring the most negatively-charged surface. Also, the results indicated that the presence of Mn(II) and/or Mn(III) impurities inside the Mn(IV)O2 structure could enhance the mineral's capacity to oxidize Cr(III). The information provided in this study will be useful in predicting the capabilities of naturally-occurring Mn oxide minerals, which are similar to the three synthetic Mn(IV)O2 investigated, to oxidize Cr(III) to toxic and mobile Cr(VI) in the soil of contaminated sites.
Authors:
Gautier Landrot; Matthew Allen Ginder-Vogel; Kenneth John Livi; Jeff P Fitts; Donald L Sparks
Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2012-10-11
Journal Detail:
Title:  Environmental science & technology     Volume:  -     ISSN:  1520-5851     ISO Abbreviation:  Environ. Sci. Technol.     Publication Date:  2012 Oct 
Date Detail:
Created Date:  2012-10-11     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0213155     Medline TA:  Environ Sci Technol     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
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