The potential leaching and mobilization of trace elements from FGD-gypsum of a coal-fired power plant under water re-circulation conditions

Patricia Cordoba-Sola, Iria Castro, M Mercedes Maroto-Valer, Xavier Querol

Research output: Contribution to journalArticle

7 Citations (Scopus)
36 Downloads (Pure)

Abstract

Experimental and geochemical modelling studies were carried out to identify mineral and solid phases containing major, minor, and trace elements and the mechanism of the retention of these elements in Flue Gas Desulphurisation (FGD)-gypsum samples from a coal-fired power plant under filtered water recirculation to the scrubber and forced oxidation conditions. The role of the pH and related environmental factors on the mobility of Li, Ni, Zn, As, Se, Mo, and U from FGD-gypsums for a comprehensive assessment of element leaching behaviour were also carried out. Results show that the extraction rate of the studied elements generally increases with decreasing the pH value of the FGD-gypsum leachates. The increase of the mobility of elements such as U, Se, and As in the FGD-gypsum entails the modification of their aqueous speciation in the leachates; UO<inf>2</inf>SO<inf>4</inf>, H<inf>2</inf>Se, and HAsO<inf>2</inf> are the aqueous complexes with the highest activities under acidic conditions. The speciation of Zn, Li, and Ni is not affected in spite of pH changes; these elements occur as free cations and associated to SO<inf>4</inf><sup>2</sup> in the FGD-gypsum leachates. The mobility of Cu and Mo decreases by decreasing the pH of the FGD-gypsum leachates, which might be associated to the precipitation of CuSe<inf>2</inf> and MoSe<inf>2</inf>, respectively. Time-of-Flight mass spectrometry of the solid phase combined with geochemical modelling of the aqueous phase has proved useful in understanding the mobility and geochemical behaviour of elements and their partitioning into FGD-gypsum samples.

Original languageEnglish
Pages (from-to)72-80
Number of pages9
JournalJournal of Environmental Sciences
Volume32
Early online date2 Apr 2015
DOIs
Publication statusPublished - 1 Jun 2015

Keywords

  • FGD-gypsum
  • Geochemical modelling studies
  • Landfills
  • Leaching
  • ToF mass spectrometry
  • Trace elements

ASJC Scopus subject areas

  • Environmental Engineering
  • Environmental Science(all)
  • Environmental Chemistry

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