Waste engine oil

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Waste engine oil is a high pollutant material that requires responsible management. Waste engine oil may cause damage to the environment when dumped into the ground or into water streams including sewers. This may result in groundwater and soil contamination . Recycling of such contaminated materials will be beneficial in reducing engine oil costs.

significant positive impact on the environment . The conventional methods of recycling of waste engine oil either requires a high cost technology such as vacuum distillation or the use of toxic materials such as sulfuric acid. These methods also produce contaminating by-products which have highly sulfur levels, especially in the Kurdistan region/Iraq. Lubricant oils have been used primarily for reducing friction between moving parts of various machinery or equipment, minimize material wear, improve the efficiency of equipment /machinery and for fuel and energy savings. Access to lubricants is essential to any modern society and not only does lubrication reduce friction and wear by interposition of a thin liquid film between moving surfaces, but it also removes heat, keeps equipment clean, and prevents corrosion. One of its important applications includes gasoline and diesel engine oils . Waste lubricating oil refers to the engine oil, transmission oil, hydraulic and cutting oils after use. It is also refers to the degradation of the fresh lubricating components that become contaminated by metals, ash, carbon residue, water, varnish, gums, and other contaminating materials, in addition to asphaltic compounds which result from the bearing surface of the engines . These oils must be changed and removed from the automobile after a few thousand kilometers of driving because of stress from serious deterioration in service. The amount of lubricating oils that is collected annually in Europe and USA is very large, approximately 1.7 to 3.5 million tons. This large amount of waste engine oils has a significant impact on both economical and environmental aspects. They cost millions of dollars to manufacture and represent a high pollutant material when disposed of. If discharged into the land, water or even burnt as a low grade fuel, this may cause serious pollution problems because they release harmful metals and other pollutants into the environment . A recommended solution for this issue is the recovery of the lubricating oil from the waste oil. Recycling processes using nontoxic and cost effective materials can be an optimum solution. Acid-clay has been used as a recycling method for used engine oil for a long time. This method has many disadvantages; it also produces large quantity of pollutants, is unable to treat modern multigrade oils and it is difficult to remove asphaltic impurities [8]. Solvent extraction has replaced acid treatment as the method of choice for improving the oxidative stability and viscosity/temperature characteristics of base oils. The solvent selectively dissolves the undesired aromatic components (the extract), leaving the desirable saturated components, especially alkanes, as a separate phase (the raffinate) . In one study  a mixture of methyl ethyl ketone (MEK) and 2-propanol was used as an extracting material for recycling used engine oils. Although the oil resulting from this process is comparable to that produced by the acid-clay method, its cost is high. Expensive solvents and vacuum distillation are required to carry out this method . Recently  propane was used as a solvent. Propane is capable of dissolving paraffinic or waxy material and intermediately dissolved oxygenated material. Asphaltenes which contain heavy condensed aromatic compounds and particulate matter are insoluble in the liquid propane. These properties make propane ideal for recycling the used engine oil, but there are many other issues that have to be considered. Propane is hazardous and flammable therefore this process is regarded as a hazardous process. Also, the extraction involves solvent losses, and highly skilled operating maintenance. In addition, extraction occurs at pressures higher than 10 atm and requires high pressure sealing systems which makes solvent extraction plants expensive to construct, operate and the method also produces remarkable amounts of hazardous by-products . Membrane technology is another method for regeneration of used lubricating oils. In this method three types of polymer hollow fiber membranes [polyethersulphone (PES), polyvinylidene fluoride Energies 2013, 6 1025 (PVDF), and polyacrylonitrile (PAN)] were used for recycling the used engine oils. The process is carried out at 40 °C and 0.1 MPa pressure. The process is a continuous operation as it removes metal particles and dusts from used engine oil and improves the recovered oils liquidity and flash point. Despite the above mentioned advantages, the expensive membranes may get damaged and fouled by large particles .Vacuum distillation and hydrogenation are two other methods that can be used for recycling used engine oil . The Kinetics Technology International (KTI) process is a combination of vacuum distillation and hydrofinishing. This method removes most of the contaminants from the waste oil. The process starts with atmospheric distillation to eliminate water and light hydrocarbons. This is then followed by vacuum distillation at a temperature of 250 °C. The final stage is hydrogenation of the products to eliminate the sulphur, nitrogen and oxygenated compounds. This stage is also used to improve the color and odor of the oil. The product can be of quality standard with a yield of approximately 82% and minimized polluting by-products. The disadvantage of this method is the high investment cost. In this research glacial acetic acid was used for recycling used engine oils. The method provides a lower cost process in comparison with the conventional methods due to the low cost of the acid and the moderate conditions of the process. The recycled oil obtained by this method has been shown to have potential for reuse as an engine lubricant

Thanks and regards

Chris Brown

 Associate Managing Editor

 Email: wastemanag@scholarlypub.com

 Twitter: @advancerecycle