Gaseous
arsenic emitted from coal combustion flue gas (CCFG) causes
not only severe contamination of the environment but also the failure
of selective catalytic reduction (SCR) catalysts in power plants.
Development of inexpensive and effective adsorbents or techniques
for the removal of arsenic from high-temperature CCFG is crucial.
In this study, halloysite nanotubes (HNTs) at low price were modified
with CuCl2 (CuCl2–HNTs) through ultrasound
assistance and applied for capturing As2O3(g)
in simulated flue gas (SFG). Experiments on arsenic adsorption performance,
adsorption mechanism, and adsorption energy based on density functional
theory were performed. Modification with CuCl2 clearly
enhanced the arsenic uptake capacity (approximately 12.3 mg/g) at
600 °C for SFG. The adsorbent exhibited favorable tolerance to
high concentrations of NO
x
and SO
x
. The As2O3(III) was
oxidized and transformed into As2O5(V) on the
CuCl2–HNTs. The Al–O bridge had the highest
adsorption energy for the O end of the As–O group (−2.986
eV), and the combination formed between arsenic-containing groups
and aluminum was stable. In addition, the captured arsenic could be
stabilized in the sorbent at high temperature, making it possible
to use the sorbent before the SCR system. This demonstrates that CuCl2–HNTs is a promising sorbent for arsenic oxidation
and removal from CCFG.
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