New Methodology of Solvent Selection for the Regeneration of Waste Lubricant Oil Using Greenness Criteria

Waste lubricant oil (WLO) is an absolute hazardous entry in the European List of Waste that requires proper treatment. Solvent extraction is one of the most effective deasphalting processes for the regeneration of WLO, with a strong contribution to the circular economy. This study aims to propose a new methodology for the selection of solvents for WLO regeneration, which balances technical, economical, and greenness criteria. The method involves two phases for screening a list of 154 solvents. In the first phase, five criteria were used: water and acidic properties; selectivity toward the base oil and flocculation capacity; number of carbon atoms between three and five; melting point lower than 10 °C and a boiling point between 60 and 130 °C; and yield greater than 85%. In the second phase, three metrics of sustainability were employed: greenness, efficiency, and cost. Globally, a score was attributed to each solvent based on the assessment of the individual metric. From a list of 154 solvents, 1-butanol,...