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The Heterogeneous Reverse Osmosis Membranes Based Separation of Fluorides with Fly Ash Pretreatment

100%
Thaçi B., Gashi S.
Acta Physica Polonica A
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2015
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vol. 128
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issue 2B
B-62-B-66
EN
The objective of this paper was to examine the separation efficiency of fluorides by heterogeneous reverse osmosis membranes made from cellulose acetate and modified coal with aryl diazonium salt (batch 318 K) and lignite based fly ash pretreatment. The effect of varying the feed concentration (400-100 mg/dm³) of sodium and ammonium fluorides on performances of these membranes using 400 mg/dm³ aqueous solution of sodium chloride as referent system at 1.76 MPa have been investigated. Practically no significant change in the membrane characteristics (product rate, and solute separation) by varying the above concentration of feed salt solutions. The high separation of fluoride (synthetic sample) ≈99% was obtained by resulting membranes pretreated with different amount and contact time of low cost adsorbent (fly ash) at pH 4. A sample of waste water effluents of cement industry was also treated with above membranes without pretreatment and the results are presented. These data indicate that the fluoride ion concentration are within acceptable level as far as environmental limits concerned, therefore, their practical application produced water of suitable quality, essentially free from fluorides.
2
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Assessment of Environmental Risk from Coal Using Neutron Activation Analysis

100%
Ileri R., Hacıyakupoğlu S., Esen A., Oruçığlu E., Erentürk S.
Acta Physica Polonica A
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2015
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vol. 127
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issue 4
1010-1012
EN
This study aimed to determine element concentration in coal samples and to assess Co, Cr, Se, Th and U leaching from coals exposed to a simulated coal cleaning process. Coal samples taken from a local area of Turkey were grounded and exposed to water for one month period. Then the cleaned samples were filtered and dried. The elemental concentrations in the samples before and after the cleaning procedure were determined by relative neutron activation analysis (NAA). Raw and water cleaned coal samples were irradiated in central irradiation tube of TRIGA MARK II Research Reactor at 250 kW for 6 h and measured for their activities by using high resolution gamma spectroscopy system. The results showed that leaching percentage for Se is up to 100% and for Co, Cr, Th and U up to 71%, 17%, 30%, 28% respectively.
3
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Paramagnetic Centres in Coal Macerals

100%
Słowik G., Więckowski A.
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issue 3
507-510
EN
The electron paramagnetic resonance (EPR) study of coal macerals: exinite, vitrinite and inertinite separated from clarain of the Polish medium-rank coal with carbon content of 85.6 wt% C, were performed. Using the continuous microwave saturation technique (measurements at 223 K and 291 K), as a result of numerical analysis of recorded EPR spectra of exinite, vitrinite and inertinite, their multi-component structure was shown. The EPR spectra of exinite and vitrinite consist of three component lines: one Gaussian G and two Lorentzians: L1 and L3. The EPR spectra of inertinite consist of two narrow lines with Lorentzian line shape L2 and L3. Temperature measurements of studied coal macerals in the range 100-373 K were done. It was evidenced that, in group of paramagnetic centres responsible for Lorentzian L1 component line, paramagnetic centres with thermally excited triplet states (S = 1) exist. Existence of paramagnetic centres with thermally excited triplet states was not observed in inertinite.
4
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Paramagnetic Centres in Oxidised Coal

100%
Najder-Kozdrowska L., Samoilova R., Kappl R., Hüttermann J., Więckowski A.
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issue 3
475-479
EN
This paper comprises the results obtained by continuous wave (cw)/pulse electron paramagnetic resonance spectroscopy for oxidised coals. The values of EPR linewidths are different for samples of coal treated by different chemical agents. The asymmetric EPR line shape indicates to complex composition of paramagnetic centres in coal. In coal oxidised by HNO_3 big changes of linewidth with temperature were observed. For all samples the spin-lattice relaxation time T_1 was determined by pulse EPR method. The correlation between used chemical agents and the value of T_1 was established.
5
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Groups of Paramagnetic Centres in Reduced and Methylated Low Rank Coal

88%
Pilawa B., Wachowska H., Kozłowski M., Więckowski A., Najder-Kozdrowska L.
Acta Physica Polonica A
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2015
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vol. 128
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issue 3
264-267
EN
Low rank Illinois No. 6 coal was studied by electron paramagnetic resonance EPR spectroscopy. The parameters of EPR spectra (spectroscopic splitting factors g, linewidths ΔB_{pp}, concentrations of paramagnetic centres N) were measured for row and chemically treated coal (demineralized, reduced and methylated samples). The multi-component structure of experimental spectra of this coal was proved. Two groups of paramagnetic centres responsible for broad Lorentzian 1 and narrow Lorentzian 2 lines exist in studied samples. Paramagnetic centres connected with component lines revealed different behaviour during chemical treatments.
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