Research on As2O3 adsorption enhancement characteristics of Mn-modified γ-Al2O3

Arsenic adsorption on pure gamma-Al2O3 is mostly weak so modifying gamma-Al2O3 to have better adsorption features is a focus for now. In this study, gamma-Al2O3 is modified with manganous nitrate. Then, Mn-modified gamma-Al2O3 is used for As2O3 adsorption experiments under different conditions. In the meantime, molecular dynamics (MD) simulations and density functional theory (DFT) calculations are operated to investigate As2O3 adsorption characteristics in mesoscale and microscale, respectively. According to DFT calculations, the arsenic adsorption strength of modified gamma-Al2O3 increases mainly because of more electrons being transferred into a stable status with the help of Mn. In the meantime, transition state (TS) energy barriers of physisorption structures being transferred to chemisorption are reduced owing to catalytic effects of MnO2. As to MD simulations, As2O3 molecules are aggregated together to distribute more uniformly on Mn-modified gamma-Al2O3 than pure gamma-Al2O3, which is in favor of capturing more arsenic at higher temperatures. Besides, for experimental results, arsenic adsorption amounts of Mn-modified gamma-Al2O3 under different conditions are bigger than those of pure gamma-Al2O3 which verifies the DFT and MD calculations. This study would supply crucial references for utilizing Mn-modified gamma-Al2O3 in coal-fired power plants to efficiently capture arsenic.