High-Purity Fatty Acid n‑Octyl Esters from Housefly (Musca domestica L.) Larval Lipids, a Potential New Biolubricant Source

• Published in: Energy & fuels 2017-10, Vol.31 (10), p.10966-10974
• Main Authors: Cai, Zi-zhe, Wu, Sheng-qing, Sun, Guo, Niu, Yi, Zheng, Dong, Peng, Shi-yi, Yang, Wen-zhe, Wang, Yong, Yang, Depo
• Format: Article
• Language: English
• ISSN: 0887-0624; 1520-5029
• DOI: 10.1021/acs.energyfuels.7b01996

With the cost of traditional lipid feedstocks constituting 70% of the total cost of biolubricant production, it is urgent to find a new lipid source for the biodiesel and biolubricant industry. With the elevated acid value (61.8 mg of KOH/g) of housefly larval lipids, converting the free fatty acid (FFA) into a biolubricant could serve as a value-added approach to the larval diesel industry, other than pretreatment by acid-catalyzed esterification for biodiesel production. This study developed a method of producing high-purity fatty acid n-octyl esters (FAOEs) from housefly (Musca domestica L.) larvae. The housefly larva free fatty acids (HLFFAs) from the larva lipids were obtained by wipe-film short-path distillation. FAOEs were produced by esterifying n-octanol with HLFFAs (catalyzed by benzenesulfonic acid under the following conditions: catalyst loading, 2 wt %; molar ratio of n-octanol to FFA, 3:1; temperature, 100 °C; time, 2 h). Excess n-octanol was effectively removed by high-vacuum (80 Pa) distillation at 90 °C. The unreacted FFAs were neutralized using demethylated crude glycerin, which is a byproduct of biodiesel production. A practical method of producing high-purity fatty acid n-octyl esters (99.19 wt %) derived from housefly larva lipids was thus developed, and the product could serve as a replacement for certain low-viscosity mineral lubricants such as liquid paraffin, polyalphaolefin 6, and SN 500.