Adsorption and reaction mechanism of arsenic vapors over γ-Al2O3 in the simulated flue gas containing acid gases. (August 2017)

• Record Type: Journal Article
• Authors: Hu, Hongyun; Chen, Dunkui; Liu, Huan; Yang, Yuhan; Cai, Hexun; Shen, Junhao; Yao, Hong
• Is Part Of: Chemosphere. Volume 180(2017)
• Page Start: 186
• Page End: 191
• Publication Date: 2017-08
• Subjects: Arsenic adsorption -- γ-Al2O3 -- Acid gases -- Species -- Regeneration; Pollution -- Periodicals; Pollution -- Physiological effect -- Periodicals; Environmental sciences -- Periodicals; Atmospheric chemistry -- Periodicals; 551.511
• DOI: 10.1016/j.chemosphere.2017.03.114
• Languages: English
• ISSNs: 0045-6535

Abstract

Abstract: Arsenic emission from fuel combustion and metal smelting flue gas causes serious pollution. Addition of sorbents is a promising way for the arsenic capture from high temperature flue gas. However, it is difficult to remove arsenic from SO2 /HCl-rich flue gas due to the competitive reaction of the sorbents with arsenic and these acid gases. To solve this problem, arsenic adsorption over γ-Al2 O3 was studied in this work to evaluate its adsorption mechanism, resistance to acid gases as well as regeneration behavior. The results show that γ-Al2 O3 had good resistance to acid gases and the arsenic adsorption by γ-Al2 O3 could be effectively carried out at a wide temperature range between 573 and 1023 K. Nevertheless, adsorption at higher-temperature (like 1173 K) leaded to the decrease of surface area and the rearrangement of crystal structure of γ-Al2 O3, reducing the active sites for arsenic adsorption. The adsorption of arsenic was confirmed to occur at different active sites in γ-Al2 O3 by forming various adsorbed species. Increasing temperature facilitated arsenic transformation into more stable chemisorbed As 3+ and As 5+ which were difficult to remove through thermal treatment regeneration. Fortunately, the regeneration of spent γ-Al2 O3 could be well performed using NaOH solution. Graphical abstract: Highlights: As capture by γ-Al2 O3 was effective at a wide temperature range from 573 to 1023 K. γ-Al2 O3 showed good resistance to acid gases in the process for arsenic adsorption. As was adsorbed at different active sites in γ-Al2 O3 by forming various species. As capture was inhibited by the change of γ-Al2 O3 structure at high temperatures. The regeneration of spent γ-Al2 O3 could be well performed using NaOH solution.