Heavy oil fraction removal from sand using hydrotropes containing oil-in-water microemulsions

Oil-in-water microemulsions were prepared with a nonionic surfactant and different cosurfactants using as the oil phase a hydrocarbon mixture of linear, cyclic and aromatic hydrocarbons. This organic mixture ensures the solubilization of the crude oil heavy fraction, such as asphaltenes and resins, which are insoluble in normal aliphatic solvents. The results showed that it was possible to obtain microemulsions with the mixture of hydrocarbons used. The microemulsion region inside the pseudo-ternary phase diagram was slightly increased using different hydrotropic compounds. The results indicate that the addition of hydrotropes causes a reduction in the minimum amount of surfactant and cosurfactant necessary for the solubilization of the oil phase. When samples of sand contaminated with asphaltene residue were treated with these microemulsions, it was observed that the oil fraction was incorporated in the organic phase of the dispersion and that the contaminant was almost totally removed. These studies are being extended aiming at the development alternative techniques to remove oil from soils contaminated with organic compounds.