TREATMENT OF WASTE ENGINE OIL USING OPTIMIZED ACID/CLAY REFINING METHOD

Abstract

This paper addresses treatment of waste engine oils (WEO) treated by acid/clay refining method using glacial acetic acid. An optimization of the process parameters in terms of settling time, stirring speed and mixing temperature of method was developed to improve the process efficiency and oil recovery. The quality of the treated WEO was evaluated in terms of viscosity index and flash point value. The comparable properties of the treated oil to that fresh engine oil were achieved with 95% similarity at process conditions of setting time of 24 hours, temperature of 50 °C and mixing speed of 150 rpm respectively. The optimization study found that settling time plays the most significant parameters of the process followed by mixing temperature. Compared to previous study with the same method, this study improved the efficiency of the process by 84% in terms of viscosity index and flash point of treated oil. Four brands of WEO (Liqui Moly, Castrol, Shell and Pennzoil) were further compared at optimized conditions. It is found that the method is generally suitable to treat most of the WEO. The sludge collected at optimum treatment conditions which were analyzed using EDS and FESEM, showing the identified rough heteregenous shaped particles as carbon (97%), calcium (1.12%), zinc (0.74%), sulphur (0.73%) and phosphorus (0.29%). The finding from this study provide the information on the best process condition for treating WEO as well as to provide knowledge on particles presence in WEO.