Synergistic enhancement of CO2 adsorption on MgO-nanoparticle-loaded corn straw biochar: insights from ball milling pathways and DFT calculations

To enhance the application potential of straw-based biochar in CO 2 capture, this study prepared nano-MgO-supported biochar (MgO/BMBC) via a combined ball-milling and MgO-modified pyrolysis activation process. The CO 2 adsorption performance of the material was systematically investigated, and the adsorption mechanism was elucidated through structure-property relationship analysis and density functional theory (DFT) calculations. The results indicate that wet-milled biochar (W-MgO@BMBC) exhibits a hierarchical pore structure and a specific surface area of 323.14 m 2 ·g −1 . This method promotes the formation of a hierarchical porous structure, the presence of oxygen-containing basic groups, and the loading of MgO. The maximum CO 2 capture capacity reached 1.29 mol·kg −1 under conditions of 273 K and 1 bar, with the mechanism of action being a synergistic effect of physical and chemical adsorption. The CO 2 /N 2 selectivity is 40.28, and after five cycles, the adsorption capacity loss is significant at approximately 40%, necessitating further improvement. DFT calculations indicate that enhancing the affinity between MgO/BMBC and CO 2 and facilitating electron transfer reduces the adsorption energy, thereby improving CO 2 capture performance. This study provides a new strategy for the preparation of highly efficient, low-cost solid CO 2 adsorbents.