Identifying the active sites of carbonaceous surface for the adsorption of gaseous arsenic trioxide: A theoretical study

Abstract

Arsenic pollutants released from coal-fired power plant caused great harm to human health and the environment due to its high toxicity and bioaccumulation. Gaseous As2O3 is one of the main arsenic pollutants in coal power plant flue gas. The literature suggests that As2O3 can be effectively removed by the unburned carbon. However, the active sites of the unburned carbon for As2O3 adsorption has not been clearly identified, which greatly hinders the development of effective adsorbents. To reveal the active sites of As2O3 adsorption, the adsorption characteristic of As2O3 on different carbonaceous surfaces were systematically investigated through density functional theory calculations. In this work, the adsorption mechanism of As2O3 was studied through Mayer bond order, overlap population Density-of-states (OPDOS), and Atomic Dipole Moment Corrected Hirshfeld (ADCH) charge analysis. The adsorption of As2O3 on defective surfaces is associated with stable chemisorption, and surface defects can significantly improve the adsorption energy of As2O3. This theoretical study clarifies the adsorption active sites in carbonaceous surfaces and provide theoretical guidance for the development of efficient adsorbents for As2O3.