Detrimental effects of SO2 on gaseous mercury(II) adsorption and retention by CaO-based sorbent traps: Competition and heterogeneous reduction | Health & Environmental Research Online (HERO)

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Citation
Tags

HERO ID

6574978

Reference Type

Journal Article

Title

Detrimental effects of SO2 on gaseous mercury(II) adsorption and retention by CaO-based sorbent traps: Competition and heterogeneous reduction

Author(s)

Tang, H; You, W; Wang, Z; Li, C; Zhu, C; Cai, L; Duan, Y; ,

Year

2020

Is Peer Reviewed?

Yes

Journal

Journal of Hazardous Materials
ISSN: 0304-3894
EISSN: 1873-3336

Publisher

ELSEVIER

Location

AMSTERDAM

Volume

387

Page Numbers

Language

English

PMID

31796365

DOI

10.1016/j.jhazmat.2019.121679

Web of Science Id

WOS:000514758500047

URL

http://://WOS:000514758500047
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Abstract

Reliable gaseous Hg(II) measurement is crucial to mercury emissions control from coal-fired flue gas, but Hg(II) sampling under SO2 condition could probably increase the uncertainty of sorbent traps. CaO-AcS synthesized from calcium acetate and porous support were previously demonstrated to be effective for Hg(II) trapping under SO2-free condition. This work further evaluated SO2 influence on its Hg(II) retention ability via integrating experimental and DFT computational studies. Increased breakthrough rate of HgCl2 was found in a two-section CaO-AcS trap under SO2 conditions. Significant basicity and porosity loss of CaO-AcS were attributed to the formation of agglomerate CaSO3. Hg0 release from CaO-AcS samples suggested potential reactions between Hg(II) and SO2. The detected HgO and Hg2SO4 species by Hg-TPD in CaO-AcS further confirmed this speculation. Moreover, both competition and reduction effects of SO2 on surface-bound Hg(II) species were substantiated by DFT calculations. SO2 showed a stronger interaction with CaO than HgCl2 because SO2 has a lower LUMO level and can accept electrons easier. Reaction pathways indicated Hg(II) was partially reduced to Hg2SO4 under SO2-deficient condition, or directly reduced to Hg0 under SO2-rich condition. This work fully proposed the SO2 influence mechanisms and improvement countermeasures for practical gaseous Hg(II) sampling.

Keywords

Hg(II) sampling; SO2 influence; CaO-based trap; Flue gas; kcl-coated denuders; fired power-plant; oxidized mercury; flue-gas; elemental mercury; electron; removal; approximation; methodology; Engineering; Environmental Sciences & Ecology