Unveiling the innovation: Optimized biodiesel production from emerging Acer truncatum Bunge seed oil using novel and highly effective alkaline ionic liquid catalyst

Herein, three novel alkaline ionic liquids (ILs) with nitrogen-containing heterocycles were prepared via a two-step method, which were then utilized as excellent catalysts for biodiesel synthesis through transesterification of emerging Acer truncatum Bunge seed oil (ATBSO) and methanol. The alkaline ILs exhibited favorable catalytic performance, with 1-(2.3-dihydroxy)-propyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene) hydroxide ([DPTD][OH]) exhibiting the highest catalytic efficiency among them. Furthermore, the effect of the independent variables and their interactions on biodiesel yield were assessed and optimized using response surface methodology (RSM). Under the optimal parameters, which consisted of a reaction temperature of 71 °C, a reaction time of 137 min, a substrate molar ratio of methanol to ATBSO of 12:1, and a catalyst loading of 1.3 wt%, the biodiesel yield reached a maximum of 97.3 %. The catalytic transesterification of ATBSO for the preparation of biodiesel exhibited an activation energy (Ea), enthalpy (ΔH), entropy (ΔS) and the Gibbs free energy (ΔG) of 35.14 kJ·mol−1, 32.37 kJ·mol−1, −178.80 J·mol−1·K−1 and 93.70 kJ·mol−1 at 343 K, respectively. It is worth noting that, after the reaction, an automatic phase separation between biodiesel and the catalyst occurred, minimizing the processes of product isolation and purification. Additionally, [DPTD][OH] exhibited favorable reusability over the four reaction cycles, providing a sustainable and environmentally friendly approach for biodiesel production. The biodiesel obtained from ATBSO demonstrated excellent physicochemical properties, such as good cold flow property and flash point, which conform to the biodiesel standards outlined in ASTM D6751 and EN 14212.