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Postęp w technologii i badaniach niskotemperaturowych ogniw paliwowych

100%

Więckowski A.

Biuletyn Polskiego Stowarzyszenia Wodoru i Ogniw Paliwowych

2008

issue 3

31-42

Microwave saturation of EPR spectra of oxidised coal

51%

Pilawa B., Więckowski A., Pietrzak R., Wachowska H.

Open Chemistry

2007

vol. 5

issue 1

330-340

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. [...]

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1 Biuletyn Polskiego Stowarzyszenia Wodoru i Ogniw Paliwowych

1 Open Chemistry

1 2008

1 2007

2 Więckowski A.

1 Pietrzak R.

1 Pilawa B.

1 Wachowska H.

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Postęp w technologii i badaniach niskotemperaturowych ogniw paliwowych

Microwave saturation of EPR spectra of oxidised coal