Base oil recovery from waste lubricant oil by polar solvent extraction intensified by ultrasound

This paper proposes a greener approach to the intensification of base oil recovery for truck engines (32,500 km of use) using ethanol, propan-2-ol, 2-methylpropan-1-ol, and butan-1-ol as solvents for the extraction of base oil, combining mechanical stirring (220 rpm) and ultrasound (25 degrees C, 24 kHz, and 400 W). The results indicated that the recovery yields of the base oil, using the mechanical stirring and ultrasound (MS-US) system, for ethanol, propan-2-ol, 2-methylpropan-1-ol, and butan-1-ol were approximately 3.1, 25.6, 71.6, and 85.5%, respectively. By contrast, the recovery yields using only mechanical stirring were 8.8, 28.9, 58.9, and 76.1%, respectively. The system with pre-extraction could effectively remove Ca (85.3-93.0%), Mg (67.2-82.9%), Na (31.7-62.5%), and Zn (0.0-71.7%). Finally, the results showed a reduction of almost 100% for the concentrations of Al, Cr, Fe, and Mo in the pre-extraction system. The mechanical stirring (5 min) and ultrasound (5 min) system were able to intensify the extraction process using environmentally friendly solvents.

Automated summary

The study proposed a greener approach to intensify base oil recovery for truck engines using environmentally friendly solvents and a combination of mechanical stirring and ultrasound. The system with pre-extraction effectively removed impurities, while the mechanical stirring and ultrasound system enhanced the extraction process.