Santos, Adriana Vieira dosSantos, Verena Filgueiras Borges dosFernandes, Virgínia CruzFigueiredo, Sónia AdrianaGrosso, ClaraDelerue‑Matos, CristinaSimonelli, GeorgeSantos, Luiz Carlos Lobato dosFernandes, Virgínia2025-09-192025-09-192025-08-08dos Santos, A. V., dos Santos, V. F. B., Fernandes, V. C., Figueiredo, S. A., Grosso, C., Delerue-Matos, C., Simonelli, G., & dos Santos, L. C. L. (2025). Eco-friendly cleaning agent applied for ex situ remediation of beach sand contaminated with crude oil. Environmental Geochemistry and Health, 47(9), 366. https://doi.org/10.1007/s10653-025-02678-40269-4042http://hdl.handle.net/10400.22/30467Coastal oil spills cause significant adverse effects, and removing weathered crude oil mixed with sand remains a considerable challenge. To address this, an environmentally friendly cleaning agent was formulated using a vegetable oil-based microemulsion for sediment cleaning. The relationship between microemulsion composition and its efficiency in cleaning oil-contaminated sediments in coastal environments was investigated. Component selection followed criteria of low toxicity and high biodegradability, including pine oil as the oily phase, distilled water as the aqueous phase, saponified coconut oil as the surfactant, and isopropyl alcohol as the cosurfactant. Pseudoternary phase diagrams were constructed using a cosurfactant/surfactant ratio of 10. The microemulsified cleaning agents were characterized and optimized using Scheffé's simplex lattice design, with refractive index, viscosity, conductivity, and specific gravity as response variables. Biodegradable microemulsion systems were successfully applied to remediate oil-contaminated beach sand, where higher proportions of the oily phase, specifically 30% and 60%, demonstrated excellent oil removal performance. The remediation process effectively incorporated the crude oil contaminant into the oily phase of the microemulsion, achieving a maximum removal efficiency of 90%. Additionally, the microemulsion exhibited stability for 30 days and maintained efficiency for up to five reuse cycles. This study highlights the potential of environmentally friendly microemulsions derived from vegetable oils for effective remediation of beach sand contaminated with crude oil, particularly through in situ soil washing or soil flushing, reinforcing the viability and sustainability of these cleaning agents.engCrude oil spillSoil flushingVegetable oil-based microemulsionsReuse microemulsionresearch article10.1007/s10653-025-02678-41573-2983