Effect of CO2 on the As2O3 adsorption over carbonaceous surface: Experiment and quantum chemistry study

The adsorption characteristics of the As2O3 over carbonaceous surface in the presence of CO2 were systematically studied by experiment and density functional theory (DFT). The experimental results show that CO2 has a negative effect on the adsorption of arsenic by activated carbon. In addition, quantum chemistry calculations were employed to study the mechanism for CO2 influence on arsenic adsorption. Calculation results show that carbonaceous surface tends to react with CO2 compared to As2O3 in the flue gas. Compared to the As2O3 adsorption over the complete carbonaceous surface, there is a noticeable decrease for the adsorption energy over the defective carbonaceous surface. Besides, with the pre-assembled CO2 adsorption over the carbonaceous surface, the As2O3 adsorption energy decreases, indicating CO2 has the negative effect on As2O3 adsorption. By means of Hirshfeld atomic charges analysis, CO2 adsorbed on carbonaceous surface would weaken the activity of adsorption sites and inhibit the As2O3 adsorption. The experiment and theoretical study figured out the influences mechanism of CO2 on the As2O3 adsorption and provide a theoretical foundation for gaseous arsenic removal using carbonaceous surface.