Protic Ionic Liquids as Eco-Friendly Surfactants for Oil Spill Remediation: Synthesis, Characterization, and Performance Evaluation

This study presents an innovative approach by synthesizing and evaluating protic ionic liquids (PILs) as sustainable surfactants for oil spill remediation, as an alternative to the highly toxic chemical dispersants conventionally used, as well as to the surface-active ionic liquids reported in the literature, which are typically based on imidazolium cations and halogenated anions. Four PILsbutyrolactam butyrate (BTB), 2-methyl-hydroxyethylammonium propanoate (2-HEAP), 2-methyl-hydroxyethylammonium acetate (2-HEAA), and choline laurate [CHL]-[LAU]were synthesized and analyzed for physicochemical and surfactant properties. Characterization included Fourier transform infrared (FTIR) and nuclear magnetic resonance (NMR) spectroscopy, while density, viscosity, surface tension, and emulsification performance were also evaluated. Among them, [CHL]-[LAU] exhibited the best performance, significantly reducing surface tension (22.7 mN/m) and forming stable emulsions with motor oil and kerosene. It also demonstrated an effective critical micellar concentration (CMC) of 29.9 mmol/L, enabling efficient hydrocarbon solubilization. In oil removal tests, [CHL]-[LAU] performed comparably to the commercial surfactant SDS, while in oil displacement area tests, it outperformed SDS, covering up to 93.5% of the surface. Toxicity tests using <i>Artemia salina</i> confirmed that [CHL]-[LAU] is less toxic than conventional surfactants. These findings highlight [CHL]-[LAU] as a promising and environmentally friendly surfactant for oil spill remediation, offering an effective and sustainable alternative to conventional dispersants.