Experimental and theoretical study of arsenic removal by porous carbon from MSW incineration flue gas

Abstract

Municipal solid waste incineration is considered to be one of the major anthropogenic arsenic emission sources. Arsenic removal from incineration flue gas remains a great challenge. Biomass-based porous carbon sorbent was synthesized by hydrothermal method coupled with CO2 physical activation to eliminate gaseous arsenic from incineration flue gas. The porous carbon has large surface area and developed porous structure. The arsenic removal capacity of porous carbon reached 10.04 mg/g at 350 °C. Porous carbon showed remarkable resistance to SO2 and HCl poisoning. NO and CO2 exhibited little effects on arsenic removal. H2O vapor lightly inhibited arsenic removal at 350 °C. The captured arsenic mainly existed in the form of As5+, the oxidation process played a crucial role in As2O3 removal by porous carbon. The spent porous carbon can be regenerated by means of alkali leaching, which facilitates the recycling of sorbent. The porous carbon showed excellent regenerability for arsenic removal. Density functional theory calculations were performed to reveal the atomic-level mechanism of arsenic adsorption by porous carbon. Both physisorption and chemisorption mechanisms are responsible for As2O3 adsorption on porous carbon surface. The stronger adsorption is accompanied by the deeper electron transfer phenomenon.