Advance recovery approach for efficient recovery of waste lubricating oil by different material formulations

Abstract

The rapid growth of population with increased facilities for comfort nowadays leads to a drastic depletion of natural resources. The present work emphasizes the re-refining process of waste lubricating oil by the solvent-extraction flocculation process. Re-refining is considered by many as a preferred option in conserving resources, minimizing waste, and reducing environmental hazards to a great extent. The effect of various parameters like refining time, refining temperature, solvent to waste oil ratio, flocculant dosage, adsorbent to distilled oil ratio has been elaborately studied, and the optimum yield percent was obtained at 33 °C of refining temperature, 20 min of refining time with a solvent to waste oil ratio of 5:1 (w/w). Various solvents like iso-butanol and n-butanol were used, and iso-butanol was found to produce a higher yield of 72%, which is 2% higher than the solvent n-butanol. Calcium hydroxide was used as a flocculant, and a concentration of 2 kg of flocculant per kg of solvent was optimum. The flashpoint, ash content, and viscosity index of re-refined oil were 210 °C, 0.25 g, and 175, respectively, comparable to virgin lube oil. The purity and the existence of oxidation products were elaborately analyzed by FTIR and GC–MS analysis. Thus, the refined oil obtained can effectively mitigate the ever-growing oil crisis and help create a healthy and pollution-free environment.