Effect of sodium alginate and corn starch bio‐flocculants on the maximization of yield % of refined lubricant obtained by environmental friendly extractive–flocculative approach: A comparative optimization study

Abstract Long‐term usage of lubricating oil produces waste that poses a risk to the environment, human health, and the economy. To create a sustainable ecosystem, the waste oil must be treated and disposed of properly. The extraction flocculation procedure for recovering used engine oil is the focus of the current study. To maximize the percentage recovery of refined oil, a comparative evaluation and optimization research was conducted using two distinct bio‐flocculants (sodium alginate and corn starch). The quality of refined oil and its surface morphology, with integration of elemental analysis, has been extensively addressed using fuller's earth as an adsorbent. The optimal parameters assessed were: extraction time of 60 and 80 min; temperatures of 50 and 60°C; solvent to waste oil ratios of 4.98:1 and 3:1; and flocculant dosages of 2 and 1 g/kg of solvent, for 1‐butanol‐Corn starch and 1‐butanol‐sodium alginate, respectively. The yield of recovered oil with 1‐butanol‐sodium alginate was found to be higher (91.81%) than 1‐butanol‐corn starch (88.25%) due to its higher tendency for eradication of carbonaceous matter, as well as other oxidative products from waste oil. The physico‐chemical parameters of the refined oil, utilizing sodium alginate as a bio‐flocculant, were determined to be a viscosity of 17.32 cSt at 100°C, a flash point of 231°C, and a pour point of −32°C, which closely resembles that of fresh oil. The refined oil can effectively alleviate the oil crisis and foster a sustainable green atmosphere.