Assessing the efficacy of three bio‐based flocculants in the reclamation of spent lubricating oil

Abstract

The current study encompasses a comprehensive assessment of three biopolymeric flocculants on the overall performance of recycling waste lubricating oil to achieve a higher percentage recovery, flocculation efficacy, and better quality of recovered base oil. The findings reveal that with experimental conditions such as (i) mixing time of 80 min; (ii) agitation speed of 400 rpm; (iii) reaction temperature 50°C; (iv) solvent to waste oil ratio 3:1 g/g; and (v) flocculant dosage 1 g/ kg of solvents, 1‐butanol and sodium alginate gives highest percentage yield of 91% followed by corn starch of 89.10% and xanthan gum of 87.18% as bio‐polymer flocculant. The effects of various process parameters of bio‐flocculants on flocculation efficiency are expounded. With the process parameters of (i) initial pH of 5.9, 6.0, and 6.2; (ii) mixing time − 59, 60, and 63 min; and (iii) solution temperature of 59, 60, and 62.2°C, maximum flocculation efficacy (% sludge removal) of 16.24%, 13.01%, and 14.09% were attained for the cases of refined oil treated with sodium alginate, corn starch, and xanthan gum, respectively. Results also reveal that the physicochemical properties of refined base oil treated with 1‐butanol and sodium alginate as bio flocculant are almost close to the virgin lubricating oil. The optimum recovery of high‐quality base oil with the adoption of green technology and solvent–bio flocculant combination can mitigate the environmental impact of waste oil and create an energy‐efficient sustainable condition for the regeneration of re‐refined base oil.