Molecular Dynamics Simulation of the Aggregation Behavior of Typical Aromatic Pollutants and Its Influence on the n-Octanol-Air Partition Coefficient.

Abstract

The aggregation behavior of typical aromatic pollutants in the n-octanol phase and its influence on the n-octanol-air partition coefficient (K_OA) were investigated using molecular dynamics simulation. The aggregate proportion of selected aromatic pollutants gradually increased with increasing simulation time and then reached a dynamic equilibrium state. It is interesting to find that the higher the concentration of aromatic pollutants, the more aggregates formed in the n-octanol phase. Log K_OA values of these aromatic pollutants were subsequently estimated based on the percentages of aggregates and the solvation free energy from the gas phase to the n-octanol phase. The log K_OA values were also found to gradually increase with increasing concentration. Therefore, the effect of concentration on K_OA should be taken into consideration during the analysis of the environmental behavior and transport of these aromatic pollutants. In addition, it was found that π-π interactions drive the formation of different numbers of aggregates for different aromatic pollutants, a phenomenon that affects the K_OA values of aromatic pollutants. The above results shed some light on the effects of aggregates and concentration on the partition behavior of aromatic pollutants and provide a theoretical basis for the correction of K_OA of aromatic pollutants in the environment.