Deep insight into the effect of NaCl/HCl/SO2/CO2 in simulated flue gas on gas-phase arsenic adsorption over mineral oxide sorbents

• Published in: Journal of hazardous materials 2021-02, Vol.403, p.123617-123617, Article 123617
• Main Authors: Yu, Shenghui, Zhang, Cheng, Ma, Lun, Tan, Peng, Fang, Qingyan, Chen, Gang
• Format: Article
• Language: English
• Subjects: Arsenic adsorption; Flue gas components; Mineral oxide sorbents; Reaction sites
• ISSN: 0304-3894; 1873-3336
• DOI: 10.1016/j.jhazmat.2020.123617

Fig. Schematic diagram of competing for active sites on the surface of sorbent particles. [Display omitted] •Arsenic adsorption over mineral oxide sorbents in simulated flue gas was studied.•The preferred order of arsenic adsorption is CaO > MgO/Fe2O3> NaCl > Al2O3 > SiO2.•The effect mechanism of NaCl on the physical properties of sorbents was revealed.•Element distribution maps of the sorbents after arsenic adsorption was obtained.•The competition between acid gases and gas-phase arsenic over sorbents was clarified. Coal combustion is one of the major pathways by which arsenic enters the ecological environment. An effective method to control arsenic emissions in-furnace is to transform the arsenic from a vapour to fly ash particles using mineral sorbents. However, flue gas components have a significant effect on gas-phase arsenic adsorption, which limits the industrial application of mineral sorbents. In this paper, the effect mechanism of flue gas components (NaCl/HCl/SO2/CO2) on gas-phase arsenic adsorption over different mineral oxide sorbents was investigated. The results demonstrate that the order of arsenic adsorption is CaO > MgO/Fe2O3> NaCl > Al2O3 > SiO2. NaCl promotes the arsenic adsorption of CaO above 800 °C, and the arsenic removal efficiency of CaO with 5 % NaCl is 52.51 % at 900 °C. NaCl inhibits the arsenic adsorption of MgO and Fe2O3, and promotes arsenic adsorption by Al2O3 and SiO2. Acid gases inhibit arsenic adsorption by the sorbents and the order of the inhibition intensity of acid gases at 700 °C is HCl > SO2 > CO2. The active sites (CaO, FeO, or AlO bonds) in the sorbents are the main reaction sites for arsenic adsorption, and captured arsenic is in the form of AsO21− and AsO43-.