Molecular dynamics simulation of polycyclic aromatic hydrocarbons solubilization and distribution mechanisms in Triton X-100 micelles for environmental remediation

Polycyclic aromatic hydrocarbons (PAHs) are widespread environmental pollutants with low water solubility and high persistence. Triton X-100 (TX-100), a typical nonionic surfactant, is widely used to mobilize PAHs from contaminated environments. The solubilization capacity of TX-100 is influenced by micelle properties and the solubilization characteristics of PAHs within the micelle. However, the molecular-level mechanisms underlying PAHs solubilization in TX-100 micelles remain unclear. To explore the molecular basis of PAH solubilization in micelles, all-atom molecular dynamics (MD) simulations were performed to construct TX-100 micelles and investigate the solubilization of three model PAHs, naphthalene (NAP), pyrene (PYR), and phenanthrene (PHE), within the micelle. Simulation revealed that regardless of concentrations, NAP, PYR, and PHE can be solubilized in both the shell and core regions of the TX-100 micelles, with 85–97 % of time residing in the shell region due to its larger volume. Furthermore, all three PAHs exhibited similar solubilization sites, showing a preference for interacting with the TX-100 tails (C18–C22). Such behavior can be attributed to their dynamic movement, the wide distribution of TX-100 tails within the micelles, and the large overall size of the TX-100 micelle. The solubilized PAHs showed negligible impact on micelle properties, as evidenced by minimal changes in TX-100 monomer conformation and internal dynamics, and in the size and shape of the micelle. This study enhances our understanding of the solubilization of PAHs in TX-100 micelles and their mutual interactions at the microscopic level, providing valuable insights for the more effective application of TX-100 in remediating PAH-contaminated sites.