Surface Functionalization of Synthesized Sodium Alginate from Brown Algae for Maximizing the Yield of Re-Refined Used Lubricating Oil Using Extraction-Flocculation-an Environment-Friendly Approach

This study aims at efficient, economically feasible, and environmentally friendly regeneration of waste lubricant by surface-functionalized bio flocculant via extractive-flocculative technique for maximization of yield. Further, optimization has also been escalated for designing the optimal process parameters (such as reaction time, solvent to waste oil ratio, and bio-flocculant concentration) for enhancing the quality and cost effectiveness of the regenerated product. FTIR, SEM, and TGA analysis were used to characterize the synthesized bio-flocculant. GC-MS, FTIR, and NMR analysis were used to characterize the chemical composition, chemical nature, and functional group of virgin, used, and re-refined lubricant. Experimental findings showed that a grafting efficacy of 76% can be achieved with optimal conditions of reaction temperature of 70 degrees C, irradiation time of 6 min, 2.5 wt. % monomer concentration and 800 W microwave radiation. Maximum yield of 94% can be obtained with optimal process constraints such as reaction time of 60 min, refining temperature of 80 degrees C, the ratio of solvent and waste oil of 3:1 g/g and 1 g/kg of solvent flocculant dosage, grafting % of 76. Fuel characterization studies reveal that the fuel characteristics of re-refined lubricant are analogous to those of fresh oil.