Synergistic approach to nanoparticle and carbon reduction via bioresource-derived fuel blends and two-stage electrostatic precipitation

• Dual-strategy cuts diesel gaseous and ultrafine emissions using green fuel and ESP. • COME from agro-waste enhances efficiency and supports sustainable fuel solutions. • CuO nanoparticles boost combustion while reducing NOx without harming BTE. • Two-stage ESP captures post-combustion nanoparticles with high efficiency. • Integrated approach aligns with global emission goals in environmental technology. The growing concern over ultrafine particle emissions from diesel engines, coupled with the need to reduce carbon output, demands integrated solutions. This study presents a dual-intervention approach that couples bioresource-derived fuel modification with two-stage electrostatic precipitation (ESP). Cottonseed oil methyl ester (COME) was blended with diesel at 15% and 30% v/v; the 30% blend was further doped with 100 ppm CuO to enhance combustion. Tests on a single-cylinder CI engine showed that DF30COME+CuO delivered the highest thermal-performance gain (BTE +11%) and reduced BSFC by 8% at full load. Across operating loads, HC declined by 29–46% and CO by 28–43% compared with diesel. NOx was effectively unchanged versus diesel (about +1%) yet 7–8% lower than DF30COME, reflecting CuO-assisted control of biodiesel-driven NOx. To target post-combustion particulates, a custom-engineered two-stage ESP featuring punched-hole electrodes was developed and integrated into the exhaust system. SEM/EDX/XRD/FTIR of CuO before use and after ESP capture confirmed morphological and crystallographic transformations and verified nanoparticle retention. This integrated fuel-aftertreatment framework offers a scalable, low-cost pathway toward cleaner diesel operation and advances environmental process engineering for simultaneous gaseous and nanoparticulate control.