Extraction and Characterization of Pyrolysis Oil from E-Waste Plastics with SiO₂ Nano-Additives for Enhanced Performance in CI Engines

This study investigates the performance and emission characteristics of a common-rail direct injection (CRDI) diesel engine fueled with E-waste plastic oil (WPO) blended with silicon dioxide (SiO₂) nanoparticles. Pyrolysis-derived WPO was mixed with diesel at a 20% volumetric ratio (WPO20), with SiO₂ nanoparticles added at concentrations of 40, 80, and 120 ppm (denoted as WPO20 + SiO40, WPO20 + SiO80, and WPO20 + SiO120). Engine tests under variable load conditions revealed that SiO₂ additives improved combustion efficiency, yielding a 1.8–4.3% increase in brake thermal efficiency (BTE) and a 3.5–6.9% reduction in brake-specific fuel consumption (BSFC) compared to unmodified WPO20. Emissions analysis showed 12–18% lower CO, 9–14% reduced HC, and 11–19% decreased smoke opacity relative to baseline diesel, attributed to SiO₂’s catalytic oxidation and enhanced air-fuel mixing. However, NOx emissions rose by 2.1–5.7% due to elevated in-cylinder temperatures from accelerated combustion. Contaminant mitigation strategies, including dual-stage filtration and surfactant-assisted ultrasonication, ensured stable nanoparticle dispersion in WPO blends. While WPO + SiO₂ blends exhibited marginally lower BTE gains than conventional biodiesel they demonstrated superior CO/HC reduction potential, positioning waste plastic oil as a viable, sustainable alternative fuel. The findings underscore the role of nanoadditives in optimizing pyrolyzed fuels for diesel engines, though NOx control and long-term injector compatibility require further investigation.