Removal of As2O3 in coal-fired flue gas by metal oxides: Effects of adsorption temperature and flue gas components

Arsenic emitted from coal-fired power plants has attracted widespread attention. Metal oxides are promising adsorbents for arsenic removal, but the influence laws and mechanisms of temperature and flue gas components on their arsenic removal performance are unclear. In this work, systematic research on the effects of adsorption temperature and flue gas components on As2O3 removal by Fe2O3, CaO, and γ-Al2O3 was conducted. The results show that As2O3 removal ability satisfies Fe2O3 > CaO > γ-Al2O3 at 300–900 °C, which is mainly related to their basic site strength. At 500 °C, Fe2O3 has the largest As2O3 removal capacity (adsorption capacity: 158.4 μg/g; removal efficiency: 84.68%). Increasing adsorption temperature is beneficial to the transformation of arsenic to high-valent arsenic (As(V)) on the surface of Fe2O3, CaO, and γ-Al2O3. Low-concentration SO2 will compete with As2O3 for adsorption on the three metal oxides surface, which thereby inhibits their As2O3 removal ability. The presence of NO has an obvious inhibitory effect on the As2O3 removal of Fe2O3, CaO, and γ-Al2O3, which is little affected by the change of NO concentration. Fe2O3 is a metal oxide adsorbent with strong arsenic removal potential. Compared with basic simulated flue gas (BSFG) components, the presence of SO2, NO, and SO2+NO in the simulated flue gas all inhibits the adsorption of As2O3 by Fe2O3. Finally, future work on arsenic removal from coal-fired flue gas adsorbents is presented. This work has important engineering applications and theoretical research guiding significance for the development of high-performance arsenic removal adsorbents.