Speciation, characterization, and mobility of As, Se, and Hg in flue gas desulphurization residues

Journal Article · Sat Mar 01 04:00:00 EST 2008 · Environmental Science and Technology

DOI:https://doi.org/10.1021/es702479n· OSTI ID:21036889

Al-Abed, Souhail R; Jegadeesan, Gautham; Scheckel, Kirk G; Tolaymat, Thabet ^[1]

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1. United States Environmental Protection Agency, Cincinnati, OH (United States). National Risk Management Research Laboratory

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. 34 refs., 3 figs., 4 tabs.

• OSTI ID: 21036889
• Journal Information: Environmental Science and Technology, Journal Name: Environmental Science and Technology Journal Issue: 5 Vol. 42; ISSN ESTHAG; ISSN 0013-936X
• Country of Publication: United States
• Language: English

Related Subjects

01 COAL, LIGNITE, AND PEAT
20 FOSSIL-FUELED POWER PLANTS
54 ENVIRONMENTAL SCIENCES
ABSORPTION
ARSENIC
CHEMICAL STATE
COAL
COMBUSTION PRODUCTS
DESULFURIZATION
ELEMENTS
ENVIRONMENTAL IMPACTS
FLUE GAS
FOSSIL-FUEL POWER PLANTS
IRON OXIDES
LEACHING
MERCURY
MOBILITY
PH VALUE
RESIDUES
SELENIUM
SOLVENT EXTRACTION
STABILITY
TRACE AMOUNTS
WASTE DISPOSAL
WASTE PRODUCT UTILIZATION
X-RAY FLUORESCENCE ANALYSIS
X-RAY SPECTROSCOPY