TY - JOUR
T1 - The key roles of Fe-bearing minerals on arsenic capture and speciation transformation during high-As bituminous coal combustion
T2 - Experimental and theoretical investigations
AU - Fu, Biao
AU - Hower, James C.
AU - Li, Shuai
AU - Huang, Yongda
AU - Zhang, Yue
AU - Hu, Hongyun
AU - Liu, Huimin
AU - Zhou, Jun
AU - Zhang, Shiding
AU - Liu, Jingjing
AU - Yao, Hong
N1 - Publisher Copyright:
© 2021 Elsevier B.V.
PY - 2021/8/5
Y1 - 2021/8/5
N2 - The conversion of As vapor released from coal combustion to less hazardous solids is an important process to alleviate As pollution especially for high-As coal burning, but the roles of key ash components are still in debate. Here, we used multiple analytical methods across the micro to bulk scale and density functional theory to provide quantitative information on As speciation in fly ash and clarify the roles of ash components on As retention. Fly ash samples derived from the high-As bituminous coal-fired power plants showed a chemical composition of typical Class F fly ash. In-situ electron probe microanalysis (EPMA) was for the first time used to quantify and distinguish the inter-particle As distribution difference within coal fly ash. The spatial distribution of As was consistent with Fe, O, and sometimes with Ca. Grain-scale distribution of As in coal fly ash was quantified and As concentrations in single ash particles followed the order of Fe-oxides > aluminosilicates > unburned carbon > quartz. Sequential extraction and Wagner chemical plot of As confirmed that Fe minerals rather than Al-/Ca-bearing minerals played a vital role in capturing and oxidizing As3+ into solid phase (As5+). Magnetite content in fly ash well-correlated with the increase ratio of As before and after magnetic separation, suggesting magnetite enhanced As enrichment in fly ash. Density functional theory (DFT) indicated that the bridges O sites of octahedral structure on Fe3O4 (111) surface were likely strong active sites for As2O3 adsorption. This study highlights the importance of magnetite on As transformation during bituminous or high-rank coal combustion in power plants and has great implications for developing effective techniques for As removal.
AB - The conversion of As vapor released from coal combustion to less hazardous solids is an important process to alleviate As pollution especially for high-As coal burning, but the roles of key ash components are still in debate. Here, we used multiple analytical methods across the micro to bulk scale and density functional theory to provide quantitative information on As speciation in fly ash and clarify the roles of ash components on As retention. Fly ash samples derived from the high-As bituminous coal-fired power plants showed a chemical composition of typical Class F fly ash. In-situ electron probe microanalysis (EPMA) was for the first time used to quantify and distinguish the inter-particle As distribution difference within coal fly ash. The spatial distribution of As was consistent with Fe, O, and sometimes with Ca. Grain-scale distribution of As in coal fly ash was quantified and As concentrations in single ash particles followed the order of Fe-oxides > aluminosilicates > unburned carbon > quartz. Sequential extraction and Wagner chemical plot of As confirmed that Fe minerals rather than Al-/Ca-bearing minerals played a vital role in capturing and oxidizing As3+ into solid phase (As5+). Magnetite content in fly ash well-correlated with the increase ratio of As before and after magnetic separation, suggesting magnetite enhanced As enrichment in fly ash. Density functional theory (DFT) indicated that the bridges O sites of octahedral structure on Fe3O4 (111) surface were likely strong active sites for As2O3 adsorption. This study highlights the importance of magnetite on As transformation during bituminous or high-rank coal combustion in power plants and has great implications for developing effective techniques for As removal.
KW - Arsenic retention
KW - Capture mechanisms
KW - Coal-fired power plants
KW - Fly ashes
KW - Speciation determination
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U2 - 10.1016/j.jhazmat.2021.125610
DO - 10.1016/j.jhazmat.2021.125610
M3 - Article
C2 - 33730644
AN - SCOPUS:85102372551
SN - 0304-3894
VL - 415
JO - Journal of Hazardous Materials
JF - Journal of Hazardous Materials
M1 - 125610
ER -