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Waste Oil Re-Refining by Using Solvent Extraction Method

Waste Lubricating oils may be re-refined by treatment with a polar solvent. For this purpose a solvent must be used that dissolves the base oil and flocculates major part of additives and impurities. In this research, some polar solvents such as ketones and alcohols have been used, and the performances of them in two different temperatures have been compared. Waste oil has been prepared from different garages that nowadays have been used as feed in re-refining factories by acid was treatment. Ethanol, 2-propanol, 1-butanol, butanone and n-hexane have been used and the performances of them in ambient temperature (25 °C) and 50 °C have been compared for different solvent to waste oil ratio. For 1-butanol and butanone curves of sedimentation have been plotted in different solvent to waste oil ratios. Results indicate that 1-butanol at ambient temperature and the ratio of 3 of the solvent to waste oil, has the best performance. But in some cases the polar solvent induces the formation of an electrically stabilized dispersion therefore reduces the velocity of sedimentation. To overcome this problem various amounts of potassium hydroxide have been added to solution. In this context, 1,3, and 4 gr/L concentrations of potassium hydroxide have been used and the best result has been seen for the concentration of 3 gr/L of potassium hydroxide.