Recovery and characterization of useful benzene derivatives from spent engine oil through solvent extraction

Abstract

Engine oils are contaminated with hazardous species resulted from the oxidative degradation, which cause serious environmental issues. In this study, the extraction of useful hydrocarbons (HCs) from used engine oil through solvent extraction followed by separation in a column via adsorption is reported. n-Hexane, toluene, ethyl acetate, and their mixture (ethyl acetate/n-hexane) were used as solvent for extraction over powdered silica packed column, and the extracted samples were analyzed through thin layer chromatography, gas chromatography–mass spectrometry and Fourier transform infra-red spectroscopic techniques. Useful HCs like 1-fluoro heptane, n-hexane, methyl cyclopentane, toluene, p-xylene, o-xylene, toluene, benzaldehyde, 2,3-dimethyl pentane, and benzene-1,2-dicarboxylic acid were identified and subsequently distilled with respective percent recovery of 91, 71, 46, 45, 18, 08, 07, 06, 04 and 02%. The reported HC derivatives were obtained by interacting the sample oil with non-polar solvents (n-hexane and toluene) and slightly polar solvent (10% ethyl acetate/n-hexane mixture) in column which extracted the compounds having similar chemical nature in an appreciable amount via Londer dispersion forces and dipole-dipole interactions. The findings of this study concluded that the extraction of valuable benzene derivatives through highly cost-effective solvent extraction strategy is a promising alternative to the conventional burning and reclamation of spent engine oil. Witnessing the high efficiency and cost-effectiveness of the current process, it could be extended to the extraction of other useful compounds from used oils and concomitantly alleviating the related environmental pollution on larger scale.