Regeneration of used lubricating oil by solvent extraction and phase diagram analysis

Abstract

The methodology presented in this work is developed for the removal of sludge and thus regenerate the properties of the engine lubricating synthetic oil for its reuse. This was achieved removing contaminants from waste lubricant (WL) by solvent extraction. The technique used analyze ternary phase diagrams of solvent mixtures with WL and dehydrated WL determine regions that allow maximum wet sludge removal. The pair of solvents chosen to create ternary phase diagrams with WL consists of a polar solvent and a non-polar solvent. The pairs of solvents selected were methyl isobutyl ketone (MIBK) and methanol with toluene according to their miscibility with WL and their Hildebrand solubility parameter values. The liquid systems solvent mixture with WL corresponding to the points selected in the ternary phase diagrams were centrifuged to quantify the percentage of wet sludge removal (PWSR) to evaluate the efficiency of the process. The properties of the recovered lubricants were evaluated carrying out tests of viscosity and density at different temperatures as well as flash point. The results were compared to those of the WLO and the new lubricant (NL).

Keywords

• Waste lubricant
• Solvent extraction
• Ternary diagram
• Regeneration