Abstract: Solvent refining is not only an environmental-friendly process but also one of the cheapest and most efficient processes for waste lubricating oils recycling. In this work, single factor experimental design was adopted, four carbon alcohols were used as polar extraction solvents, polyacrylamide (PAM) was used as flocculant to regenerate waste lubricating oil. The optimal process conditions were obtained as follows: using isobutyl alcohol as extraction solvent, a solvent/oil mass ratio of 5, a PAM amount of 1.0%, a refining time of 15 min and refining temperature of 25℃ (room temperature). The yield of the recovered oil under such conditions was 82.1%, some of the physicochemical properties of this recovered oil were improved significantly, such as viscosity index reached more than 130, the flash point was over 200℃, the content of carbon residue was less than 0.01% and the acid number was 0.01 mgKOH/g, which indicated that this technology for waste lubricating oil recycling is feasible and may have a promising application future.

Key words: single factor experiment, solvent refining, waste lubricating oil, recovered oil, physicochemical properties