As2O3 adsorption enhancement over Ni-modified γ-Al2O3 in complex flue gas constituents

Arsenic adsorption capacities of gamma-Al2O3 are easily affected by some flue gas constituents (e.g. SO2, NOx) based on previous studies. Therefore, promotion of arsenic adsorption performances under effects of different flue gas constituents is necessary. In this study, gamma-Al2O3 plays a role of the raw adsorbent and nickel nitrate acts as the modifying agent for gamma-Al2O3. Then, Ni-modified gamma-Al2O3 is used as the adsorbent for arsenic adsorption experiments. Besides experiments, molecular dynamics (MD) simulations and density functional theory (DFT) calculations are performed to reveal mesoscopic and microscopic adsorption mechanisms, respectively. As to DFT calculations, the average arsenic adsorption energies are promoted by 77.5 kJ/mol, which means that nearly all adsorption structures belong to stable chemisorption. For MD simulations, the adverse molecular collision and aggregation are weakened to make the total arsenic adsorption efficiencies increase by 15.8 % averagely. As far as experiments are concerned, the arsenic adsorption amounts of Ni-modified gamma-Al2O3 are averagely 0.033 mg/g bigger than those of pure gamma-Al2O3 (i.e. 16.5 % in adsorption efficiencies) under some conditions, consistently corresponding to results of DFT and MD calculations. The whole understanding of this study from above three aspects can provide valuable information for applying Ni-modified gamma-Al2O3 to removing arsenic in real industries.