As2O3 removal from coal-fired flue gas by the carbon-based adsorbent: Effects of adsorption temperature and flue gas components

Abstract

Gaseous As2O3 emitted from the coal-fired power plant is one of the most carcinogenic and harmful pollutants. In this work, the commercial activated carbon (AC), wood chip-based biomass coke (BC), and KOH activated high-sulfur petroleum coke (PC) were selected, and the effects of adsorption temperature and flue gas components on gaseous As2O3 removal of the carbon-based adsorbents were investigated. The results show that under the basic adsorption conditions, the As2O3 removal ability satisfies BC > PC > AC with the best arsenic removal ability of BC at 150 ℃. Increasing the adsorption temperature benefits the oxidation of As3+ to As5+ on the surface of the three carbon-based adsorbents. Oxygen-containing functional groups (C–O and O–C=O), Al2O3, K2S, and K2SO4 are the main active sites for As2O3 chemisorption. Overall, increasing adsorption temperature leads to the first increase and then decrease in arsenic removal ability of carbon-based adsorbents. Physical adsorption is the main reason for the change in their arsenic removal ability. The weakening degree of physical adsorption is higher than the promotion of chemisorption with increasing adsorption temperature. NO has inhibitory effects on the As2O3 removal by BC. Low concentration (<4000 ppm) SO2 can promote the As2O3 removal by BC due to the formation of SO42- and the increased content of oxygen-containing functional groups.