Simulating Adsorption Of Aromatic Organic Pollutants On N-doped Single-Walled Carbon Nanotubes In Aqueous Phase

Nitrogen-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. Thus, it is important to study the adsorption of organic compounds on N-CNTs in water.Currently, a great deal of research has been conducted on N-CNTs’ preparation, characterization, electrochemical, and biological catalysis. However, only few studies have been performed on the adsorption of organic compounds on N-CNTs in water. As the ideal models, pristine CNTs have usually been used to simulate adsorption of compounds on CNTs. However, many researches do not consider the real doping concentrations and configurations of the CNTs. In this study, we constructed 20 kinds of nitrogen-doped single-walled carbon nanotubes (N-SWNTs) with different doping configurations and doping concentrations. Then we simulated the adsorption of aromatic pollutants on N-SWNTs by density functional theory (DFT) calculations.Our simulation results indicated that N doping configurations and doping concentrations have a certain effect on not only the stability of N-SWNTs, but also the adsorption affinity of aromatic compounds on N-SWNTs. Pyrid-N doped SWNTs with vacancy defect have a good performance on the adsorption. The adsorption of aromatic compounds on N-SWNTs in water is physisorption. Hydrophobic interaction and π-πstacking 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.