SHALE OIL RECOVERY FROM OIL SHALE SLUDGE USING SOLVENT EXTRACTION AND SURFACTANT WASHING

Shale oil recovery from oil shale sludge can reclaim secondary energy source and has drawn widespread attention in recent years. In this study, three oil recovery approaches, namely surfactant washing, solvent extraction, and the combination of the two procedures, were investigated to compare their oil removal capacities. Results showed that optimum conditions for surfactant washing were as follows: stirring rate 250 rpm, reaction temperature 80 degrees C, liquid-to-solid mass ratio 7: 1, duration 30 min and surfactant solution concentration 6g/L. In case of solvent extraction, ethanol achieved the highest extraction yield, 89.53%, and petroleum ether (PE) performed with the shortest extraction time. Solvent extraction was more promising than surfactant washing in removing oil components. In the combined process, surfactant sodium dodecyl sulfate (SDS) washing and different solvent extractions contributed to each other's oil removal capacity. GC-MS analysis showed that the extracted oil mainly contained saturates and 1-alkenes in the range of C-11-C-34, and that the previous surfactant washing could enhance the leaching of light hydrocarbons from oil shale sludge when using methyl ethyl ketone (MEK) and dichloromethane (DCM) extractions. The extracted oils could be recovered through distillation, which needed a hermetic apparatus to prevent the loss of oil components.