Evaluation of the chemical dispersion of weathered petroleum and oils using the dispersibility efficiency test by the SFT method
Name: AMANDA SOUZA AMARAL
Publication date: 11/07/2025
Examining board:
Name |
Role |
|---|---|
| ALVARO CUNHA NETO | Examinador Interno |
| CLEOCIR JOSE DALMASCHIO | Presidente |
| VERÔNICA SANTOS DE MORAIS | Examinador Externo |
Summary: Oil spill-related environmental disasters pose significant threats to marine and coastal ecosystems, demanding mitigation strategies capable of ensuring fast and effective responses. Among the main response techniques, the use of chemical dispersants stands out for its ability to reduce interfacial tension between oil and water, thereby facilitating the formation of smaller oil droplets that are more prone to biodegradation. The efficiency of this approach depends both on the oil’s dispersibility and on environmental factors such as wind and ocean currents. This dispersibility, in turn, varies according to the chemical composition and physicochemical properties of each type of crude oil. In this study, the Swirling Flask Test (SFT), a widely used method required by regulatory agencies, was applied to evaluate the dispersion efficiency of the commercial dispersants Corexit EC9500A and Finasol OSR 52 across different samples of crude and weathered oils. The analyses included measurements of density, viscosity, resin content, asphaltene content and SAP+A fraction. Dispersion efficiency was determined based on the amount of hydrocarbons dispersed, which is directly influenced by the oil's physicochemical properties. This assessment is crucial for devising effective response strategies that enhance containment measures and protect environmentally sensitive areas. The results indicated that the API gravity and chemical composition of the oils significantly influenced dispersion performance, with water salinity being the most impactful environmental parameter. Additionally, statistical techniques such as linear regression and principal component analysis (PCA) were applied to identify correlations and patterns. The findings reinforce the relevance of the SFT as a technical tool for contingency planning and for the informed selection of dispersants based on oil type and environmental conditions.
