X-Ray fluorescence determination of F, P, S, As and heavy metals in coal fractions and in soils containing them
S. I. SHTEL’MAKH, G. V. PASHKOVA, A. N. ZHILICHEVA, M. V. DANILOVA
Institute of the Earth’s Crust, Siberian Branch of the Russian Academy of Sciences, Irkutsk, Russia
Keywords: X-ray fluorescence analysis, coal fractions, soils, clarke, maximum permissible concentrations
Abstract
The procedure for the quantitative determination of F, P, S, V, Cr, Co, Ni, Cu, Zn, As, Pb, Th, and U in the samples of coal and in soil samples containing coal is described. X-Ray fluorescence (XRF) analysis was carried out using wavelength-dispersive X-ray fluorescence spectrometer S8 TIGER (Bruker, Germany). Measurements were carried out in the vacuum mode. The dried samples were prepared in the form of pressed tablets. To obtain calibration characteristics and carry out metrological studies, a set of certified reference materials (CRMs) of shale, coal ash, sediments and soils of different chemical composition was chosen, and mixtures with different CRMs powders and graphite content were prepared. The ratio of CRMs to graphite was determined according to the data on total carbon content in the objects under investigation, and the data on the ash content of coal. To account for mutual influences of the elements, the a-correction method was used, in most cases introducing the fluorescence intensities of elements present in the samples (carbon, etc.) as influencing factors. The calculated values of the detection limits for the elements under determination vary from 0.6 to 20 mg/kg. The accuracy of XRF analysis results was controlled using CRMs of shale (SGR1 and SDC1), anomalous silt (SGH5) and black soil (SP1), as well as the mixtures of SGHM3/graphite (1 : 4) and DVT/graphite (1 : 3). It has been determined with t-test that the results of XRF analysis do not contain significant systematic errors. The procedure for X-ray fluorescence determination of F, P, S, V, Cr, Co, Ni, Cu, Zn, As, Pb, Th and U was used to study the distribution of elements in the samples of coal fractions from the deposits of the Irkutsk Region and in the samples of soils containing these fractions, which were collected in the residential area of the Oktyabrsky district of the city of Irkutsk during summer 2024. Based on XRF data, the conclusion concerning the effect of long-term coal presence in soils on their elemental composition is made.
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