Enhanced solubilization and mechanistic insights: unraveling the role of EO chain length in synergistic pyrene removal by AE3P/AEOn surfactants.

Pyrene, a four-ring polycyclic aromatic hydrocarbon (PAHs), presents significant challenges in environmental remediation due to its extremely low water solubility and recalcitrance to removal. Surfactant-Enhanced Remediation (SER) represents a promising strategy to address this issue. This study systematically investigated the synergistic solubilization of pyrene by blending anionic surfactant aliphatic alcohol polyoxyethylene ether phosphates (AE3P) with nonionic surfactant fatty alcohol polyoxyethylene ethers (AEOn, n = 3, 5, 7, 9) at a 1:1 mass ratio, with a focus on the influence of ethylene oxide (EO) chain length The solubilization efficiency of the mixed surfactant systems was assessed using high-performance liquid chromatography with Ultraviolet Detection (HPLC-UV), transmission electron microscopy (TEM), dynamic light scattering (DLS), stress-rheometer, zeta potential, fluorescence spectroscopy, and 1H NMR spectroscopy, and compared to that of the individual components. Results indicated that the solubilization capacity for pyrene increased significantly with the number of ethylene oxide (EO) units in AEOn. The AE3P/AEO9 system showed optimal performance, with a solubility (Sw) of 80.05 mg/L and a molar solubilization ratio (MSR) of 2.135 × 10-2. The longer EO chains facilitated a structural transition of the mixed micelles from spherical to wormlike configurations, which enlarged the hydrophobic core volume and reduced the polarity of the palisade layer. thereby substantially enhancing pyrene solubilization. ffectively, thereby substantially enhancing pyrene solubilization. This approach provided a theoretical foundation for the development of efficient and cost-effective remediation strategies for PAHs-contaminated soils, and demonstrated considerable potential for practical application.