From ethyl biodiesel to biolubricants: Options for an Indian mustard integrated biorefinery toward a green and circular economy

International audience; This work aims to analyze whether Indian mustard can be harnessed within a biorefinery system to generate energy carriers and high value-added products. Within this objective, two options of harnessing Indian mustard seed oil (IMSO) were investigated, the first for the production of ethyl biodiesel (IMSOEEs) and the second for the production of a biolubricant (IMSO2E1HEs) by transesterification of the unpurified IMSOEEs with 2-ethyl-1-hexanol (2E1H). Furthermore, low cost and environmentally-friendly conversion processes were targeted. The biofuel was obtained under mild conditions of ethanolysis (35 °C, atmospheric pressure, ethanol to oil molar ratio of 8, 1.1 wt% KOH, and 50 min) carried out in two-stages separated by addition of recycled glycerol, and followed by dry-purification with Indian mustard stems-based adsorbent. In order to enhance biolubricant yield, reactive distillation with optimized operating pressure was selected (0.05 bar, 70 °C, 2 wt% KOH, 2E1H to IMSOEEs molar ratio of 2, 65 min), followed by bubble-washing (assisted with citric acid) and then vacuum distillation (inferior to 0.01 bar). The produced IMSOEEs met the basic biodiesel properties with a satisfactory ester content (95.8 wt%). Similarly, a high conversion of IMOEEs (93 wt%) was reached for the biolubricant, leading to an IMSO2E1HE product that exhibited satisfactory properties, and thus has the potential to act as a biolubricant. Nevertheless, these results could be improved with a pre-treatment of the departure IMSO to remove species that are not glycerides, such as glucosinolates. Thereby, ensuring that the produced ethyl biodiesel conforms strictly to industry specifications.