Influence of Nitric Acid Treatment in Different Media on X-ray Structural Parameters of Coal

The treatment of coal with nitric acid in aqueous and non-aqueous media introduces changes in the chemical and spatial structure of the organic mass. Four coals of different rank have been treated with nitric acid in aqueous and glacial acetic acid media for assessing the changes in the structural p...

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Bibliographic Details
Published in:Energy & fuels 2008-11, Vol.22 (6), p.4087-4091
Main Authors: Maity, Sudip, Choudhury, Ashim
Format: Article
Language:English
Subjects:
01 COAL, LIGNITE, AND PEAT
ACETIC ACID
Applied sciences
AQUEOUS SOLUTIONS
COAL
Coal and derived products
COAL RANK
Energy
Exact sciences and technology
Fossil Fuels
Fuels
NITRATION
NITRIC ACID
OXIDATION
Processing
STRUCTURAL CHEMICAL ANALYSIS
X-RAY DIFFRACTION
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Summary:The treatment of coal with nitric acid in aqueous and non-aqueous media introduces changes in the chemical and spatial structure of the organic mass. Four coals of different rank have been treated with nitric acid in aqueous and glacial acetic acid media for assessing the changes in the structural parameters by the X-ray diffraction (XRD) technique. Slow-scan XRD has been performed for the raw and treated coals, and X-ray structural parameters (d 002, L c, and N c) and aromaticity (f a) have been determined by profile-fitting software. Considerable variation of the structural parameters has been observed with respect to the raw coals. The d 002 values have decreased in aqueous medium but increased in acetic acid medium; however, L c, N c, and f a values have increased in aqueous medium but decreased in acetic acid medium. It is also observed that considerable oxidation takes place during nitric acid treatment in aqueous medium, but nitration is the predominant phenomenon in acetic acid medium. Disordering of the coal structure increases in acetic acid medium, but a reverse trend is observed in the aqueous medium. As a result, structurally modified coals (SMCs) are derived as new coal-derived substances.
ISSN:0887-0624
1520-5029
DOI:10.1021/ef800424w