XAFS Studies of Nickel and Sulfur
Speciation in Residual Oil Fly-Ash
Particulate Matters (ROFA PM)
Sidhartha Pattanaik
Frank E. Huggins
Gerald P. Huffman
William P. Linak
C. Andrew Miller
10.1021/es061635m.s001
https://acs.figshare.com/articles/journal_contribution/XAFS_Studies_of_Nickel_and_Sulfur_Speciation_in_Residual_Oil_Fly_Ash_Particulate_Matters_ROFA_PM_/3026341
XAFS spectroscopy has been employed to evaluate the
effect of fuel compositions and combustion conditions on
the amount, form, and distribution of sulfur and nickel
in size-fractionated ROFA PM. Analysis of S K-edge XANES
establish that sulfate is abundant in all PM. However,
depending upon the combustion conditions, lesser amounts
of thiophenic sulfur, metal sulfide, and elemental sulfur
may also be observed. Least-squares fitting of Ni K-edge
XANES reveals that most of the nickel in PM is present as
bioavailable NiSO<sub>4</sub>.nH<sub>2</sub>O. The insoluble Ni mainly exists
as a minor species, as nickel ferrite in PM<sub>2.5</sub> (PM < 2.5 μm)
and nickel sulfide, Ni<i><sub>x</sub></i>S<i><sub>y</sub></i> in PM<sub>2.5+</sub> (PM > 2.5 μm). The
Ni K-edge XANES results are in agreement with the EXAFS
data. Such detailed speciation of Ni and S in PM is
needed for determining their mobility, bioavailability, and
reactivity, and hence, their role in PM toxicity. This information
is also important for understanding the mechanism of
PM formation, developing effective remediation measures,
and providing criteria for identification of potential
emission sources. Transition metals complexing with
sulfur is ubiquitous in nature. Therefore, this information
on metal sulfur complex can be critical to a large body of
environmental literature.
2007-02-15 00:00:00
XAFS
EXAFS
bioavailable NiSO 4.nH
sulfur
PM
combustion conditions
ROFA
Transition metals complexing
XANES
2.5 μ m