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http://yadda.icm.edu.pl:80/baztech/element/bwmeta1.element.baztech-aeb77a41-84f3-473c-aa68-105bf3118a49

Czasopismo

Geology, Geophysics and Environment

Tytuł artykułu

Structural and Raman spectroscopy studies of schultenite - phosphoschultenite isomorphic series

Autorzy Młynarska, M.  Manecki, M.  Bajda, T. 
Treść / Zawartość http://journals.agh.edu.pl/geol
Warianty tytułu
Konferencja XVth International Conference of Young Geologists Her'lany 2014 : Międzybrodzie Żywieckie, Poland, May, 8th-10th 2014
Języki publikacji EN
Abstrakty
EN In many countries, there is a problem of lead and arsenic soils contamination. Lead can be immobilized using phosphate amendments (Cao et al. 2003). This technique, however, results sometimes in arsenic migration. Mineral phases, which can precipitate in this conditions include schultenite PbHAsO4 and phosphoschultenite PbHPO4. Only recently it has been experimentally shown that these minerals can form a continuous solid solution series in Earth surface environments (Zembal 2012). Therefore, it is important to extend our knowledge on the properties of schultenitephos-phoschultenite solid solution series in order to solve certain environmental problems. For the first time, Raman spectroscopy was used to characterize schultenite, phosphoschultenite and their solid solutions. The main objective of this research is the identification and interpretation of systematic changes in the results of X-ray diffractometry and Raman spectroscopy applied to synthetic schultenites with various P to As ratio. Six samples were synthesized from aqueous solutions at ambient conditions. The ratio of P/(P + As) varied from 0 to 1 by 0.2 (Zembal 2012). Schultenite PbHAsO4 and phosphoschultenite PbHPO4 belong to monoclinic crystallographic system. The standard model of the P2/c symmetric group was used in the calculation of unit cell parameters. The results show systematic increase in unit cell parameters with substitution of P for As in the series: parameter a from 4,6737 to 4,8588, parameter b from 6,6381 to 6,7528 and parameter c from 5,7617 to 5,8495. The Raman spectra have also shown systematic variation in stretching and bending vibrations in the series. The ν1 stretching As-O band shifts from 463 cm-1 in schultenite PbHAsO4 to 469 cm-1 in P-substituted schultenite while ν 4 bending As-O band shifts form 824 cm-1 to 841 cm-1. Similar is observed in phosphoschultenite: the v1 stretching P-O band shifts from 555 cm-1 to 569 cm-1 and v bending P-O band shifts form 905 cm-1 to 940 cm-1 with increasing P content Observed shifts in position of Raman effects correlate linearly with As-P substitution: the bands originating from vibration modes shift to higher wave numbers with the substitution of P for As from schultenite PbHAsO4 towards phosphoschultenite PbHPO4. This can be explained by the fact that atomic mass of As is higher than that of P and that As-O bonds are longer than P-O bonds. The results extend our knowledge about schultenite-phosphoschultenite isomorphic series. Systematic shifts of Raman effects correlate strongly with chemical composition of analyzed phases. This is associated with systematic linear variation in the height (between 4,403 and 411 units for As-0 ν 4 bending band and between 825 and 70 units for P-0 v4 bending band) and area under certain peaks on Raman spectra (between 71,423 and 30,805 units for As-O ν 4 bending band and between 28,982 and 2,095 units for P-O ν 4 bending band). Current findings suggest that it is possible to estimate the overall P/(P+As) ratio in mineral samples by precise determination of the position and area under the respective Raman spectra and comparison with standard measurements.
Słowa kluczowe
EN arsenic soil contamination   phosphate amendment   arsenic migration  
Wydawca Wydawnictwa AGH
Czasopismo Geology, Geophysics and Environment
Rocznik 2014
Tom Vol. 40, no. 1
Strony 110--111
Opis fizyczny Bibliogr. 2 poz.
Twórcy
autor Młynarska, M.
  • AGH University of Science and Technology, Faculty of Geology, Geophysics and Environmental Protection, Department of Mineralogy, Petrography and Geochemistry; al. Mickiewicza 30, 30-059 Krakow, Poland, mkmlynarska@gmail.com
autor Manecki, M.
  • AGH University of Science and Technology, Faculty of Geology, Geophysics and Environmental Protection, Department of Mineralogy, Petrography and Geochemistry; al. Mickiewicza 30, 30-059 Krakow, Poland
autor Bajda, T.
  • AGH University of Science and Technology, Faculty of Geology, Geophysics and Environmental Protection, Department of Mineralogy, Petrography and Geochemistry; al. Mickiewicza 30, 30-059 Krakow, Poland
Bibliografia
1. Cao R.X., Ma L.Q., Chen M., Singh S.P. & Harris W.G., 2003. Phosphate-induced metal immobilization in a contaminated site. Environmental Pollution, 122, 19-28.
2. Zembal I. 2012. Charakterystyka roztworów stałych szultenitu PbHAsO4-PbHPO4. Department of Mineralogy, Petrography and Geochemistry, Faculty of Geology, Geophysics and Environmental Protection, AGH University of Science and Technology [M.Sc. thesis].
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