| Lube oils are the most valuable but minor constituents in crude oil. because of complicated physics and chemistry changes lube oils become to used lube oils(ULO) after being used for a long time, It should be noted that heavy metals, polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs) are main contaminants in ULO; these components are highly toxic when released to the environment, particularly to water courses as this causes the obstruction of sunlight and oxygen from the atmosphere to water, which consequently poses harmful effects to aquatic lives. Difficulties also arise during the treatment as ULO is not easily removed from the contaminated water by conventional treatment methods. Hence, the best solution for ULO is the recovery of waste lube oils and re-refining to base oil instead of discarding to the environment.Different techniques have been practiced for recycling used lubricating oils. e.g. acid clay process, solvent extraction, distillation—clay filtration, chemical and clay treatment, membrane technology. Among the alternative processes proposed during recent years, solvent extraction process has received considerable attention. This process replaces successfully the classic acid/clay treatment whereby a useful organic sludge is produced instead of the toxic acidic sludge. Solvent extraction is a simple process; used oil and solvent are mixed in appropriate proportions to assure complete miscibility of the base oil in the solvent. The solvent is then recovered by distillation for recycle purpose.The most critical stage in designing this process is developing appropriate solvent extraction system that consists of type of solvent(s), extraction parameters (temperature, and solvent:oil ratio. etc.).Solvent extraction technique is one of the cheapest and most efficient processes experienced in recycling of used lubricating oils. In this paper, the performance of furfuryl alcohol in recycling used vacuum pump oil was evaluated experimentally. The effect of the most critical parameters (solvent to oil ratio, and extraction temperature) was investigated. The results show that viscosity index and refractive index of refined oil was related to the solvent to oil ratio. Viscosity index and the refractive index come to a feasible value at 80℃when solvent to oil ratio equal to 1.5. The difference of IR spectrum of the used vacuum pump oil and IR spectrum of refined vacuum pump oil show that absorption peaks at 1745cm-1 and 1160 cm 1 disappeared after solvent extraction. Under the optimal process conditions, the properties of the recovered oil were listed as follows:Viscosity (40℃) 60.56 mm2/s,25℃refractive index 1.484,recovery yield 93.9% solidifying point-1℃, density 0.8781kg/mJ.The recovery oil has a good quality,it can be reused for new base oils after adding appropriate additives. And the results of recovery of used vacuum pump oil with furfuryl alcohol are as follow; the solvent:oil ratio 1.5, refining temperature 80℃; Under the optimal Technology conditions, the properties of the recovered oil were listed as follows:Viscosity (40℃) 57.25 mm2/s,25℃refractive index 1.479,yield 92.3％.
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