Interfacial enrichment of reactive oxygen species in oil-water mixtures

Molecular dynamics simulations of a mixture of a petroleum-based oil and water reveal distinct distributions of reactive oxygen species (ROS) at the oil-water interface. Hydrophilic ROS, such as H2O2, remain confined to the aqueous phase, while HO2· and HO· radicals exhibit significant interfacial enrichment. Hydrophobic gases, O2 and O3, accumulate both in the oil phase, but only O3 shows pronounced interfacial activity. This interfacial enrichment coincides with the well-known enrichment of aromatic hydrocarbons at the oil-water boundary, suggesting increased molecular encounters between ROS and aromatics at this region. These findings highlight the oil-water interface as a reactive zone, with implications for the chemical stability of oils and for oil spill remediation via advanced oxidation processes.