ABSTRACT The characterization of Indian bituminous and subbituminous coal was performed by UVVisible–
NIR spectroscopy. Chemical leaching with varying concentration of hydrofluoric acid
was conducted on both the samples. Electronic absorption at this region was higher for higher
ranked coals. Chemical leaching increased electronic transitions in subbituminous coal with
maximum transitions for HF (10%) leached samples. The absorption maximum of benzeneoxygen
system was found between 235-270 nm and was showing a red shift with leaching. The
characteristic naphthalene ring systems (220 & 280 nm) were masked by the absorption regions
of monoaromatic rings; indicating the content of napthalenoid hydrocarbon was very low. The
bands observed in the visible region (450nm) were attributed to SO2 in the sample and was showing a red shift. The weak band at the 680 nm was attributed to the Ⅱ-Ⅱ* electronic
transitions of the polynuclear aromatic hydrocarbons which also showed red shift with leaching.
It was found that the ash content is reduced by 87.5% & 76.2% in bituminous and subbituminous
coal respectively with HF (30%) leaching.
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B. Manoj and A. Kunjomana, "Analytical Study of Two Differently Ranked Coals Using UV-VIS-NIR Spectroscopy," Journal of Minerals and Materials Characterization and Engineering, Vol. 10 No. 10, 2011, pp. 905-911. doi: 10.4236/jmmce.2011.1010070.
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