Indigenous kaolinite ore as cost effective adsorbent for re-refining of used lubricating oil

Abstract

Present study evaluates efficiency of indigenous kaolinite ore as environment friendly and low cost adsorbent for re-refining of used lubricating oil. Thermo gravimetric analysis was used to find the mass variation with rise in temperature. Different characterizing techniques such as XRD, SEM and EDS were used to see the physical and chemical changes, composition and available volume of pores before and after activation. Indigenous kaolinite ore was activated at 600 °C for one hour to increase pore size to surface area ratio. Adsorption was carried out by passing exhausted lube oil with commercial grade n-hexane in a fixed 1:2 v/v ratio over the surface of activated kaolinite in a glass column with length to diameter ratio of 16:1. The improvement in the quality of lube oil was determined by comparing quality parameters of used and refined lube oil. The process gave 95 % yield of good quality transparent pale-yellow oil having colour index of 2 with 99 % of metal reduction. Maximum capability of kaolinite ore to adsorbed oil was found to be 160 g of refined oil/200 g of kaolinite. Used adsorbent was regenerated and utilized again for the adsorption of more oil. Regenerated ore provided 150 g refined oil/200 g Kaolinite. The solvent was recovered through rotary evaporator under vacuum. Recovery of solvent and adsorbent regeneration suggest that proposed method for purification of lube oil is environment friendly and cost effective.

Keywords

• re-refining
• waste lube oil
• used lube oil
• adsorption
• indigenous kaolinite