NiO and MgO/activated carbon as an efficient CO2 adsorbent: characterization, modeling, and optimization

In this research, activated carbon (AC)-based absorbents modified with NiO and MgO were prepared by wet impregnation method for adsorption of carbon dioxide (CO2). The effect of adding (Ni(NO3)(2) 6(H2O)) and (Mg(NO3)(2) 6(H2O)) in 1, 3, 5, and 7 wt% to AC was studied. Raw AC and modified AC were characterized by ultimate analysis, scanning electron microscopy, X-ray diffraction, and surface area. In addition, response surface methodology method was used to optimize the adsorption operation condition. The five-level central composite design was applied to design the experiments for three types of adsorbents (AC, AC/NiO-3, and AC/MgO-3) in the temperature and pressure ranges of 25-80 degrees C and 2-10 bar, respectively. The results indicated that the adsorption capacity of activated carbon was modified after NiO and MgO loading, especially at higher temperatures, and the optimal concentrations were obtained 3 wt% for both of them. For better evaluation of the adsorbents behavior, experimental data were investigated by isotherm, kinetic, and thermodynamic models. The optimum adsorption capacities were obtained 121.35, 105.17 mg/g for AC/NiO-3 and AC/MgO-3, respectively.