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2007 | 5 | 1 | 330-340
Tytuł artykułu

Microwave saturation of EPR spectra of oxidised coal

Treść / Zawartość
Warianty tytułu
Języki publikacji
EN
Abstrakty
EN
Microwave saturation of multi-component EPR spectra of oxidized lignite Mequinenza (Spain) with a carbon content of 65.1 wt % and with a high sulphur content of 10.3 wt % was studied. The coal was oxidized with nitric acid (NHO3), peroxyacetic acid (PAA), and in O2/Na2CO3 system. Three different groups of paramagnetic centres exist in the coal samples analyzed. The EPR spectrum of the demineralised coal was a superposition of broad Gauss (ΔB pp = 0.75 mT), broad Lorentz 1 (ΔB pp = 0.42 mT) and narrow Lorentz 3 lines (ΔB pp = 0.08 mT). The three EPR components with linewidths: 0.58–0.77 mT (Gauss line), 0.30–0.39 mT (Lorentz 1 line) and 0.05–0.06 mT (Lorentz 3 line) were recorded for the oxidized coal. The g-values were obtained for the samples studied in the ranges 2.0043–2.0046 (Gauss lines), 2.0035–2.0038 (Lorentz 1 lines) and 2.0032–2.0034 (Lorentz 3 lines). The broad Gauss and Lorentz 1 lines saturate at low microwave powers. The narrow Lorentz 3 lines of demineralised coal were not saturated at microwave power from the range considered. After the coal oxidation with HNO3, PAA and in O2/Na2CO3 system, the microwave saturation of the narrow Lorentz 3 lines was also observed, which indicated a degradation of the multi-ring aromatic structures upon oxidation. [...]
Słowa kluczowe
Wydawca
Czasopismo
Rocznik
Tom
5
Numer
1
Strony
330-340
Opis fizyczny
Daty
wydano
2007-03-01
online
2007-03-01
Twórcy
  • Institute of Coal Chemistry, Polish Academy of Sciences, 44-121, Gliwice, Poland
  • Division of Magnetic Resonance Spectroscopy, Institute of Physics, Faculty of Physics & Astronomy, University of Zielona Góra, 65-516, Zielona Góra, Poland
  • Laboratory of Coal Chemistry and Technology, Faculty of Chemistry, Adam Mickiewicz University, 60-780, Poznań, Poland , pietrob@amu.edu.pl
  • Laboratory of Coal Chemistry and Technology, Faculty of Chemistry, Adam Mickiewicz University, 60-780, Poznań, Poland
Bibliografia
  • [1] R.R. Álvarez, C.J. Clemente and D. Gómez-Limón: “Evolution of the organic sulfur and other components during nitric acid leaching of Mequinenza coal”, Fuel, Vol. 76, (1997), pp. 1445–1450. http://dx.doi.org/10.1016/S0016-2361(97)00065-3[Crossref]
  • [2] S.R. Palmer, E.J. Hippo and X.A. Dorai: “Selective oxidation pretreatments for the enhanced desulfurization of coal”, Fuel, Vol. 74, (1995), pp. 193–200. http://dx.doi.org/10.1016/0016-2361(95)92654-O[Crossref]
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  • [4] B. Pilawa, A.B. Więckowski, R. Pietrzak and H. Wachowska: “Oxidation of demineralized coal and coal free of pyrite examined by EPR spectroscopy”, Fuel, Vol. 81, (2002), pp. 1925–1931. http://dx.doi.org/10.1016/S0016-2361(02)00131-X[Crossref]
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  • [10] Polish Standard PN-77/G-04514.11
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  • [13] B. Pilawa, A.B. Więckowski, R. Pietrzak and H. Wachowska: “Multi-Component EPR Spectra of Coals with Different Carbon Content”, Acta Physica Polonica A, Vol. 108, (2005), pp. 403–407.
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Typ dokumentu
Bibliografia
Identyfikatory
Identyfikator YADDA
bwmeta1.element.-psjd-doi-10_2478_s11532-006-0056-7
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