Speciation, characterization, and mobility of As, Se, and Hg in flue gas desulphurization residues
- 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, Vol. 42, Issue 5; Other Information: al-abed.souhail@epa.gov; ISSN 0013-936X
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
54 ENVIRONMENTAL SCIENCES
20 FOSSIL-FUELED POWER PLANTS
MOBILITY
TRACE AMOUNTS
ELEMENTS
ARSENIC
SELENIUM
MERCURY
FLUE GAS
DESULFURIZATION
CHEMICAL STATE
RESIDUES
COAL
COMBUSTION PRODUCTS
ENVIRONMENTAL IMPACTS
X-RAY FLUORESCENCE ANALYSIS
X-RAY SPECTROSCOPY
ABSORPTION
SOLVENT EXTRACTION
PH VALUE
IRON OXIDES
FOSSIL-FUEL POWER PLANTS
STABILITY
WASTE DISPOSAL
WASTE PRODUCT UTILIZATION
LEACHING