PaperID: AJERD0502-01; Pages: 1-10
Optimization of Diesel-like Fuel Production from Spent Lubricating Oil Using adsorbent Treatment
Author(s): Adamu Ibrahim ADAMU, Saidat Olanipekun GIWA, Usman Aliyu EL-NAFATY
Abstract: This research was aimed at optimizing an adsorption process used to treat spent engine oil to obtain a product that has properties similar to fresh diesel. In order to achieve this, some kaolin clay was obtained locally and made to undergo some pretreatment steps prior to sulphuric acid activation. Also, the spent engine oil used for the study was pretreated through filtration, acid/base neutralization and drying before the main treatment step. Thereafter, the face centered central composite method of response surface methodology was employed to generate thirteen runs with activated clay dosage and adsorption time as independent factors and three physical properties of the treated oil (density, flash point and viscosity) as the responses. Accordingly, adsorption experiments were carried out and the treated oil was analysed to obtain the aforementioned dependent variables. Regression analyses were carried out to obtain models that would represent the relationship between the independent variables and each of the responses. Results obtained showed that the predictors-density, viscosity and flash point data were best represented by linear, two-factor interaction and quadratic models respectively, based on their p-values which was less than 5% on 95% confidence level. Also, the coefficient of determination value for all the response was fairly close to unity. In addition, analysis of variance results showed that adsorption time and/or adsorbent dosage significantly affected the treatment process as p-value of factorial terms in all the models were significant. Density model being affected by adsorbent dosage alone can be attributed to mass transfer between the adsorbent and the adsorbate. The treated oil with best physical properties (840 kg/m3, 76 oC and 5.5 mPa.s of density, flash point and viscosity respectively) was achieved experimentally at 10 wt% adsorbent dosage and 60 min adsorption time. This optimum result was close to predicted one obtained as 842.436 kg/m3, 76.3818 oC and 5.4785 mPa.s at 9.86 wt% and 59.76 min from the numerical optimization. The optimum results revealed that the recycled spent oil has properties that are similar to diesel. Since the best properties obtained are within the standard values for diesel oil, the recycled oil can be blended with fresh diesel. The use of treated oil in diesel engine is very promising but further work needs to be done to ensure thermodynamic stability of the oil.