Effect of the Nitrogen-Containing Functional Groups on Selenium Adsorption over Activated Carbon: Experimental and Theoretical Study

Activated carbon has established itself as a crucial material, primarily due to abundant sources and its large specific surface area. In addition, chemical modification can greatly enhance the adsorption capacity of activated carbon. Thus, this work proposes to add nitrogen-containing functional groups as effective accelerators to activate and modify carbonaceous adsorbents, thereby enhancing their ability to fix gaseous selenium. This study implemented a collaborative experimental-computational scheme to systematically clarify the selenium retention mechanism of structure-modified carbonaceous adsorbents. The characterization results show that the nitrogen functional groups on the activated carbon correspond to pyridinic and pyrrolic after the modification. In addition, the adsorption experiment results show that the addition of nitrogen has a positive effect on the adsorption of gaseous selenium by activated carbon. Integrated electrostatic potential and frontier orbital analyses provide insights into the mechanisms by which nitrogen functional groups facilitate gaseous selenium adsorption. The results suggest that nitrogen doping broadens the electrostatic potential distribution range and intensifies orbital overlap effects at active sites, which are consistent with the enhanced adsorption observed experimentally and computationally. The combined experimental and computational results systematically explore the preparation of activated carbon with high adsorption performance, thereby establishing a theoretical framework for selenium capture efficiency during combustion processes.