Analytical Study of Two Differently Ranked Coals Using UV-VIS-NIR Spectroscopy

B. Manoj, A.G. Kunjomana

Department of Physics, Christ University, Hosur Road, Bangalore, Karnataka, India 560029.

DOI: 10.4236/jmmce.2011.1010070                

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.

Keywords

UV-VIS-NIR spectroscopy, Coal characterization, chemical leaching, proximateanalysis.

Conflicts of Interest

The authors declare no conflicts of interest.

References

[1]	Lazarev, A.N.,1972. “Vibrational Spectra and Structure of Silicates” Newyork: Plenum Press, pp.123-124.
[2]	Farmer, V.C., 1974. “The layer silicates:Ch 15. The Infrared Spectra of Minerals” Farmer,V.C. (Eds),London: Mineralogical Society, pp.331-363.
[3]	Osamu Ito., 1992. “Diffuse Reflectance Spectra of Coals in the UV-Visble and NIR regions” Energy and Fuels,Vol.6, pp.662-665
[4]	Manoj.B., Kunjomana.A.G.,2010.”Chemical Solubilization of Coal Using HF and Characterization of the Products by FTIR, FT Raman, SEM and Elemental Analysis”, J. of Minerals and Materials Characterization &Engineering, Vol.9 No.10, pp.919-928.
[5]	Wu.Z., Steel.K.M.,2007. “ Demineralization of a UK bituminous coal using HF and Ferric ions” Fuel, Vol.86.pp.2194-2200.
[6]	Siryuk, A.G., Radchenko, F.D., Fernandes-Games,M.M.,1979.”Analysis of Aromatic Hydrocarbons in Fuels by means of UV Absorption Spectra” Chemistry and Tech. of Fuels and oils, Vol.15, No. 7,pp. 530-534.
[7]	Satoshi Hashimoto., Hajime Akimoto,1989.”UV Absorption Spectra and Photochemical Reactions of simple aromatic Hydrocarbons in the Cryogenic Oxygen Matrix” J.Phys.Chem, Vol. 93, No.2. pp.571-577.
[8]	Olajire,A.A., AmeenA.B., Abdlil-Hammed,M., Adek2la, F.A.,2007.”Occurrence and Distribution of Metals and Porhyrins in Nigerian Coal Minerals” Journal of Fuel chemistry and technology, Vol.35, No.6, pp.641-647.
[9]	Frederick J.Kuellmes, Frank Kimbler and Janet Nuter, 1983. “ Preliminary report on the Diffuse Reflectivity of Some New Mexico Coals” Int.National Journal of Coal geology, Vol.2, No.2, pp. 261-277.
[10]	Osamu Ito,1993. “UV-Visble and Near-IR Spectra of Heat-Treated Pitches during Mesphase Formation” Carbon, Vol.31, No.3, pp. 401-406.