Simulating adsorption of organic pollutants on n-doped single-walled carbon nanotubes in water

Abstract

N-doped carbon nanotubes (N-CNTs) are widely used in various fields due to their excellent characters. They will be inevitably released into the environment with their extensive use. The adsorption of organic compounds on N-CNTs may affect the environmental behavior and ecological risk of both N-CNTs and pollutants. However, only few studies have been performed on the adsorption of organic compounds on N-CNTs in water. In this study, we constructed 20 N-doped single-walled carbon nanotubes (N-SWNTs) with different doping configurations and doping concentrations and simulated the adsorption of aromatic pollutants on N-SWNTs by density functional theory (DFT) calculations. Our simulation results indicated that N doping can increase the adsorption affinity of aromatic compounds on SWNTs, and doping configurations and doping concentrations show significant effect. Pyrid-N doped SWNTs with vacancy defect have a good performance on adsorption. The adsorption of aromatic compounds on N-SWNTs in water is physisorption. Hydrophobic interaction and π-π stacking are the main interaction forces. Functional groups of benzene derivatives (-NO2, -OH, -NH2), can enhance electrostatic interactions between the aromatics and N-SWNTs. Our study will provide a theoretical guide for future ecological risk assessment of N-SWNTs.