Tailoring Pluronic® F127-Gelucire® 48/16 mixed micellar nanostructures for efficient solubilization of petroleum-derived hydrocarbon contaminants

Abstract

Benzene (a representative monocyclic aromatic hydrocarbon, MAH) and polycyclic aromatic hydrocarbons (PAHs) are persistent hydrophobic pollutants frequently present in petroleum-related waste streams, produced waters, and contaminated aquatic environments. The low solubility of aromatic hydrocarbons in water greatly complicates their separation and remediation. Mixed micellar systems based on Pluronic® F127 and Gelucire® 48/16 were investigated to enhance the solubilization of benzene together with representative PAHs (naphthalene, anthracene, and phenanthrene) in aqueous media. The effect of sodium chloride (NaCl) on the phase behavior, structure, and solubilizing properties of mixed micellar systems was probed by cloud point (CP), dynamic light scattering (DLS), small-angle neutron scattering (SANS), and UV–visible spectroscopy. It was found that CP showed a biphasic dependence on the content of Gelucire® 48/16, whereas the increase of NaCl concentration always resulted in a decrease of the CP due to dehydration and salting out effects. From DLS and SANS, it was found that Gelucire® 48/16 contributed to the formation of compact mixed micelles, while the presence of NaCl caused the restructuring, accompanied by the enlargement of the hydrophobic core and restructuring of the hydrated corona, but keeping the overall spherical morphology unchanged. Solubilization of these aromatic hydrocarbons was improved in the studied mixed micelles. The increased solubilization capacity was attributed to enlarged hydrophobic domains, stronger hydrophobic interactions, and favorable transfer of aromatic hydrocarbons into the micellar pseudophase. The results provide a promising mixed micellar platform for enhancing the solubilization of aromatic hydrocarbons and offer mechanistic insight that may support the future development of surfactant-assisted extraction and separation processes.