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Biodiesel Production from Animal Fats Using Blast Furnace Geopolymer Heterogeneous Catalyst: Optimisation and Kinetic Study

2025; Springer Science+Business Media; Linguagem: Inglês

10.1007/s13369-024-09895-6

2193-567X

Pascal Mwenge, Aaron Luboya, Salvation Muthubi, Hilary Rutto, Tumisang Seodigeng,

Thermal and Kinetic Analysis

Abstract Biodiesel is a sustainable fuel alternative that is typically produced through a transesterification process that primarily employs homogeneous catalysts. However, they generate significant amounts of wastewater and are often non-\recyclable. This study aims to investigate the application of heterogeneous blast furnace slag geopolymer catalyst for biodiesel production from animal fat. Central composite design was employed to optimise the transesterification process, considering four key variables: the methanol-to-oil ratio (20–50 wt.%), reaction time (3–7 h), reaction temperature (30–70 °C) and catalyst-to-oil ratio (3–15 wt.%). The heterogeneous geopolymer catalyst was characterised using Fourier transform infrared spectroscopy, scanning electron microscopy, and X-ray diffraction. These analyses confirmed the geopolymerisation of the blast furnace slag and revealed no modifications to the geopolymer structure following the transesterification reaction. RSM optimisation resulted in 97.436% biodiesel yield, which was achieved at a constant stirring rate of 450 RPM, a reaction time of 6.254 h, a catalyst ratio of 9.996 wt.%, a methanol-to-animal fat ratio of 33.435 wt.%, and a reaction temperature of 50.509 °C, which was experimentally validated. The transesterification process followed pseudo-first-order reaction kinetics, with an activation energy of 43.76 kJ/mol. These findings demonstrate the potential of animal fat as a low-cost feedstock for biodiesel production catalysed by blast furnace slag geopolymer, offering a more sustainable and environmentally friendly alternative to traditional homogeneous catalysts.