Speciation, Characterization and Mobility of As, Se and Hg in Flue Gas Desulphurization Residues

Journal Article · Mon Jun 23 00:00:00 EDT 2008 · Environ. Sci. Technol.

DOI:https://doi.org/10.1021/es702479n· OSTI ID:1006633

Al-Abed, S R; Jegadeesan, G; Scheckel, K G; Tolaymat, T ^[1]

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1. EPA

Flue gas from coal combustion contains significant amounts of volatile toxic trace elements such as arsenic (As), selenium (Se), and mercury (Hg). The capture of these elements in the flue gas desulphurization (FGD) scrubber unit has resulted in generation of a metal-laden residue. With increasing reuse of the FGD residues in beneficial applications, it is important to determine metal speciation and mobility to understand the environmental impact of its reuse. In this paper, we report the solid phase speciation of As, Se, and Hg in FGD residues using X-ray absorption spectroscopy (XAS), X-ray fluorescence spectroscopy (XRF), and sequential chemical extraction (SCE) techniques. The SCE results combined with XRF data indicated a strong possibility of As association with iron oxides, whereas Se was distributed among all geochemical phases. Hg appeared to be mainly distributed in the strong-complexed phase. XRF images also suggested a strong association of Hg with Fe oxide materials within FGD residues. XAS analysis indicated that As existed in its oxidized state (As(V)), whereas Se and Hg was observed in primarily reduced states as selenite (Se(IV)) and Hg(I), respectively. The results from the SCE and variable pH leaching tests indicated that the labile fractions of As, Se, and Hg were fairly low and thus suggestive of their stability in the FGD residues. However, the presence of a fine fraction enriched in metal content in the FGD residue suggested that size fractionation is important in assessing the environmental risks associated with their reuse.

• Research Organization: Argonne National Lab. (ANL), Argonne, IL (United States). Advanced Photon Source (APS)
• Sponsoring Organization: USDOE
• OSTI ID: 1006633
• Journal Information: Environ. Sci. Technol., Vol. 42, Issue (5) ; 2008; ISSN 0013-936X
• Country of Publication: United States
• Language: ENGLISH

Related Subjects

01 COAL, LIGNITE, AND PEAT
ABSORPTION SPECTROSCOPY
ARSENIC
CAPTURE
COAL
COMBUSTION
DESULFURIZATION
ENVIRONMENTAL IMPACTS
EXTRACTION
FLUE GAS
FLUORESCENCE SPECTROSCOPY
FRACTIONATION
HAZARDS
IRON OXIDES
LEACHING
MERCURY
METALS
MOBILITY
OXIDES
RESIDUES
SCRUBBERS
SELENITES
SELENIUM
SIZE
SOLIDS
STABILITY
TRACE AMOUNTS
WASTE PRODUCT UTILIZATION