Effects of graphene oxide nanoparticles on the performance and emissions of marine microalgae-derived biodiesel-diesel blends in a diesel engine

The search for cleaner fuels has intensified as the world faces climate change, air pollution, and shrinking fossil reserves. Among renewable options, marine microalgae offer a promising pathway due to their high lipid content, rapid growth, and non-competition with food crops. This study evaluates the performance and emission behavior of a diesel engine operating on Ulva fasciata biodiesel-diesel blends (B5-B25), with a focus on the role of graphene oxide (GO) nanoparticles as a combustion enhancer. Baseline experiments identified B25 as the most effective blend, striking a balance between efficiency and emission control. To further enhance performance, Graphene oxide nanoparticles was dispersed in B25 at concentrations ranging from 35 to 75 ppm, stabilized with sodium dodecyl sulfate. The fuel tests, including analyses of its physicochemical properties, FTIR, GC–MS, XRD, and zeta potential, showed that the nanofuel was both stable and reactive. Engine tests revealed that B25 with 55 ppm GO delivered the best results: brake thermal efficiency rose by 7–10 %, torque increased by up to 35 %, and fuel consumption decreased by 8–12 % compared with neat B25. At the same time, emissions of CO, HC, PM, and NO_x dropped by 12–18 %, 14 %, 15–18 %, and 6–8 %, respectively, with all improvements statistically significant (p < 0.05). These results show that GO not only offsets biodiesel’s drawbacks but also unlocks new performance and environmental benefits, positioning GO-enriched marine algal biodiesel as a scalable, sustainable fuel for cleaner diesel engine operation.