Recycling calcium oxide nanoparticles for sustainable biodiesel production from nonedible feedstock Argemone mexicana L.

Biodiesel, seen as a key alternative to fossil fuels, has drawn significant attention. In this study, we synthesised calcium oxide (CaO) nanoparticles and assessed their catalytic efficiency for biodiesel production from the nonedible seed oil of Argemone mexicana L. The nanoparticles were thoroughly characterised using scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared (FT-IR), and thermogravimetric analysis (TGA) techniques. ASTM standard procedures were used to evaluate the fuel properties of biodiesel. Qualitative and quantitative analysis of biodiesel was conducted using gas chromatography –mass spectrometry (GC-MS), FT-IR, nuclear magnetic resonance (¹H-NMR), and nuclear mangnetic resonance (¹³C-NMR). For biodiesel synthesis, the transesterification method was followed. The synthesised nanoparticles have a size of 28 nm, and the feedstock contains 43% oil content. Optimal biodiesel yield (96%) was achieved with a 1:9 oil to methanol ratio, 15 mg of catalyst, a temperature of 55 °C, and a reaction time of 50 min. Notably, the catalytic activity of CaO nanoparticles was diminished with repeated use. Most fuel properties were confirmed to the ASTM standard ranges. The results suggest the viability of the feedstock for large-scale biodiesel production.