Adsorption of metals from recovered base oil using zeolite

Abstract

Extraction process of used lubricating oil produces organic sludge and recovered base oil. However, the base oil contains metal components as impurities. The metal components need to be removed in order to obtain a base oil that is suitable for the formulation of new lubricants. In this study, metals such as calcium, zinc, and lead from the recovered base oil were removed by using adsorption process. The parameters of adsorption such as zeolite/oil ratio, temperature, and time were investigated. The experiments were carried out using the Full Factorial Design (FFD) and Non-Factorial Response Surface Design (NFRSD) methods. The experimental results were analyzed and developed by Response Surface Methodology (RSM) to obtain empirical models. The models were the FFD no interactions, the FFD two way interactions, the linear main effects only NFRSD, the linear main effects+2ways NFRSD, the linear and quadratic main effects NFRSD, the linear and quadratic main effects+2ways NFRSD. The goodness for fit of the models were evaluated by the coefficient determination and the analysis of variances (ANOVA). The comparison study of those models shows that the linear and quadratic main effects+2ways NFRSD was the best model. Furthermore, this model was used to obtain the optimum condition of the calcium, zinc and lead removal. The results showed that the highest value of calcium removal was found to be 35.18 % at 39.9 °C, 6.2 minutes, and 0.06 g/ml of zeolite/oil ratio. The zinc removal was 35.86 % at 34.1 °C, 6.6 minutes, and 0.063 g/ml of zeolite/oil ratio. The lead removal was 86.17 % at 52.1 °C, 5.8 minutes and 0.05 g/ml of zeolite/oil ratio. The average errors of metal removal of the linear and quadratic main effects+2ways NFRSD model were 6.4 %, 15.2 %, and 4.0 %, for calcium, zinc, and lead, respectively.