Enhancement of <i>Sapindus trifoliatus</i> (soapnut) biodiesel yield, engine performance, and reduce emissions using Mg-doped CaO nanocatalyst

The use of biodiesel can reduce dependence on diesel, and the compression ignition (CI) engine's performance with is substantially low but could be improved by emulsifying nano-additives. Biodiesel production in CI engines using a homogeneous catalyst less efficient, expensive, time-consuming. In this research article, magnesium-doped calcium oxide (Mg–CaO), novel heterogeneous nanocatalyst, was synthesized then used to generate from Sapindus trifoliatus seed oil. surface characterization analyzed imaging method, energy dispersive x-ray analysis, diffraction Fourier-transform infrared spectroscopy. Then, nanocatalyst (30 ppm Mg–CaO) emulsified its nano form (STBD) at B25 (STB25% + diesel75%) blend investigated engine. highest yield 91.75% achieved 58 °C, 73 min, 4% concentration (w/w), 15:1 methanol:oil molar ratio. results were obtained STBD25, STBD25 blended CaO nano-additives (STBD25 30 CaO) Mg-doped 30ppm are compared baseline values diesel. From comparison, it revealed that Mg–CaO has greater influence combustion, performance, emission characteristics as follows: (i) in-cylinder pressure increased 3.22%, 6.24%, 9.02%, (ii) heat release rate 1.68%, 16.69%, 32.5%, (iii) brake thermal efficiency found 4.56%, 8.23%, 11.79%, (iv) hydrocarbon (HC) decreased 21.12%, 6.06%, 11.43%, (v) carbon monoxide (CO) 0.04%, 0.01%, (vi) smoke 22.61%, 8.11%, 14.25%, CaO, full load conditions. Oxides nitrogen (NOx) released while STBD25+Mg-doped engine observed decrease STBD25+CaO (by 10.72% 18.64%) an increase diesel 8.64%).