Quantitative simulationSimulation of nitrogen doping effects on benzene selective adsorption by activated carbon in aqueous conditions

Abstract

Investigating the impact of nitrogen doping on the selective adsorption of benzene on activated carbon under aqueous conditions holds significant importance in regulating nitrogen content on activated carbon precisely and enhancing benzene adsorption in the air. This study utilizes quantum chemical simulation to systematically compute the pairwise interactions of pyridine nitrogen, pyrrole nitrogen, graphite nitrogen, and their coexistence on carbon materials, including electrostatic potential, van der Waals potential, and polarity changes. We examine the adsorption of benzene and water on nitrogen-doped carbon materials and calculate the type and proportion of weak interactions in the adsorption process through energy decomposition analysis. Visual analysis of weak interactions is conducted via independent gradient scatter plots and isosurface plots. Based on this research, we investigate the influence of nitrogen doping on the competitive adsorption of benzene and water on carbon materials using adsorption energy and configuration changes. Our findings reveal that nitrogen doping disrupts the uniform electrostatic potential distribution and polarity of carbon materials. Specifically, graphite nitrogen inhibits water molecule adsorption by enhancing mutual repulsion and weakening dispersion and electrostatic interactions, consequently promoting benzene adsorption on carbon materials. Moreover, hydrogen bonds form between pyridine nitrogen, pyrrole nitrogen, and water, making carbon materials more hydrophilic. However, when combined with graphite nitrogen, this increases the negative van der Waals potential of carbon materials, further enhancing benzene adsorption. Experimental results align with the simulation, reinforcing the significance of this research in developing efficient activated carbon adsorbents for benzene under aqueous conditions.