Sci.Int.(Lahore),28(5),4393-4397,2016 ISSN 1013-5316; CODEN: SINTE 8 4393 September-October REGENERATION OF CONTAMINATED LUBRICATING OIL BY SOLVENT EXTRACTION Hassan Raza 1,* , Qazi Mohammed Omar 1 , Javeed A. Awan 1 1 Institute of Chemical Engineering & Technology, University of the Punjab, Lahore 54590, Pakistan * Corresponding Author: hassanraza.94@hotmail.com ABSTRACT: The regeneration of contaminated lubricating oil by solvent extraction method has been known as one of the inexpensive and efficient method. In this work the capability of three cheap and regeneratable solvents i.e. Methyl-ethyl-ketone (MEK), 1-butanol, 2-propanol has been tested for cleaning and regeneration of contaminated lubricating oil. Percentage oil losses were studied at varying solvent to oil ratios and extraction temperatures of 25 (298K) and 50 (323K). Percentage oil losses showed a significant decrease as the solvent to oil ratio and extraction temperatures were increased. The best results were obtained with Methyl-ethyl-ketone. The base oil samples regenerated with three solvents were tested for flash point, pour point, cloud point, kinematic viscosity and specific gravity and the results were compared with virgin lubricating oil. The base oil was regenerated from solvent-oil mixtures by treating each mixture under vacuum distillation. Key Words: Contaminated lubricating oil, Solvent extraction, regenerating used oil, extraction temperature INTRODUCTION Lubricating oil having good properties plays a vital role in terms of reduction in heat transfer and friction. Lubricants employed automobile engines can be deteriorated by different factors, such as operating conditions, quality of fuel and ambient conditions [1]. In the absence of proper treatment, the contaminated oil would be wasted that pollutes the atmosphere [2]. The contaminated lubricating oil becomes ineffective for further applications because of the degradation and impurities introduced during the usage. Degradation encompasses alterations in the aimed properties of oil as a consequence of variation in the structure of lubricating oil that results due to several processes that occur at high temperatures i.e. cracking, isomerization and polymerization reactions. During degradation about 50% of the lubricating oil is consumed [3]. Lately, different methods have been suggested for reuse of contaminated lubricating oil among which solvent extraction has been proved as a competent process because it is widely considered as the cheapest method as the solvent can be recovered for reuse [4-6]. In solvent extraction method, contaminated oil and specific solvents are usually mixed in preferred amounts to make sure that the base oil gets highly miscible within the employed solvent. The additives and contaminants that contain carbon are usually present in contaminated oil needs to be discarded by the employed solvent. These contaminants settle down and flocculate due to gravity. The solvent is then separated by the process of vacuum distillation for reuse [7]. The recovered solvent still contains minimal amount of oil, which can be separated by re-distillation to get pure solvent. Solvent extraction method can remove 10-14% impurities of the contaminated oil. This method removes maximum amount of sludge however, little amount of base oil may also be lost in sludge [8]. The purpose of this study is to reduce the oil losses by extraction with a suitable solvent. Parameters such as the amount of solvent and oil, extraction conditions and quality tests are graphically studied to determine the best possible solvent and figure out the conditions for the optimum results. The process has been explained previously in literature is used to regenerate contaminated lubricating oil by solvent extraction method [9]. The choice of solvents plays a vital role in solvent extraction and minimizing percentage oil losses. Different solvents have been used for extraction process [8, 9]. The process involves mixing procedures to ensure complete miscibility of the solvent in oil mixture. Solvent extracts the base oil, leaving low proportions of oil in the sludge phase. Extracted solvent-oil mixture is then passed through a process of vacuum distillation in order to recover the pure base oil. The base oil samples regenerated with three solvents were tested for different properties, i.e. flash point, pour point, cloud point, kinematic viscosity and specific gravity and the results were compared with virgin lubricating oil. EXPERIMENTAL WORK In this study, the retrieval of contaminated lubricating oil by solvent extraction is carried out by using only three solvents i.e. 2-propanol, 1-butanol and methyl-ethyl-ketone (MEK) as a solvent [8]. The process [10] employs the use of lubricating oil obtained from a vehicle running on a motor oil. The lubricating oil was first treated in a batch distillation unit at a temperature of 200 to remove water contents and lower hydrocarbons. The oil was then filtered to remove large impurities. After the initial steps the lubricating oil was mixed with three solvents in different ratios. The different solvent to oil ratios (vsol/voil) were varied at (0.8, 1, 1.2, 2, 3, 4 and 5). The homogenous mixtures were formed with the help of an electronic homogenizer operating at 1520 rpm for 25 minutes and at extraction temperatures of 25 and 50 in 500 ml beakers. Each mixture after mixing was transferred to the separating funnel and left for a period of 24 hours to settle under the action of gravity. After 24 hours the mixture of solvent and oil was separated from the sludge. The sludge being heavy was concentrated at the bottom of the funnel. The sludge was removed from the bottom and collected in a separate beaker where it was weighed as and termed as wet sludge. The wet sludge was heated for a duration of 15 min at 100 to evaporate any dissolved solvents. The dry sludge was left behind the weight of which was reported as . The percentage oil losses were then calculated using the formula: ()