Process design, kinetics, simulation, and techno-economic analysis of biodiesel production from Pongamia pinnata seed oil using a magnetically recyclable acidic ionic liquid catalyst

Abstract

A magnetically recyclable polymeric acidic ionic liquid nanocatalyst was fabricated in response to the demand for economical and eco-friendly one-pot conversion of inexpensive oils to biodiesel. To achieve this, Fe3O4–SiO2 nanocomposites with Fe3O4 as the core and SiO2 as the shell were prepared, and polymeric acidic ionic liquid (PAIL) was grafted over the core–shell nanocomposite (Fe3O4-SiO2) to produce Fe3O4–SiO2–PAIL nanocatalyst. The characterization results demonstrated that Fe3O4–SiO2–PAIL nanocatalyst had a strong saturation magnetization of 19.16 emu/g, a large surface area of 13.067 m2/g, and a high acid loading of 6.1 mmol/g. The Fe3O4–SiO2–PAIL was used as a heterogeneous catalyst to transesterify Pongamia pinnata seed oil (PPO) into fatty acid methyl esters (FAME). The biodiesel yield was 94.89% under optimized reaction conditions of 6.14 % (w/w) catalyst loading, methanol:oil molar ratio of 12:12, 57.37 °C, and 1.67 h. The produced FAME complied with the ASTM specifications for biodiesel. The transesterification reaction exhibited a low activation energy of 28.298 KJ/mol with pseudo-first-order kinetics. The positive values of ΔH° and ΔG° indicated that the transesterification reaction was endothermic, endergonic, and non-spontaneous. The negative value of ΔS° illustrated that the reaction is less disordered. Furthermore, the reusability studies of the heterogeneous nanocatalyst was investigated. The Fe3O4-SiO2-PAIL nanocatalyst was successfully retrieved swiftly by magnetic force, with no discernible mass loss, and employed at least six additional times without significantly losing its catalytic activity. The techno-economic analysis was executed to investigate the technical and economical feasibility of 15 metric tonne/batch biodiesel production from Pongamia pinnata seed oil using the Fe3O4–SiO2–PAIL nanocatalyst. The economic reports demonstrated a positive NPV of 20,736,000 $/year, a gross margin of 9.41%, and a biodiesel minimum selling price of 0.926 $ with a payback period of 1.88 years. This work paves the way for the sustainable use of P. pinnata as a feedstock for biodiesel production using the Fe3O4–SiO2–PAIL nanocatalyst under specified circumstances.