A novel biodegradable nanoparticle as a robust biodiesel antioxidant, and fuel additive for improvement of diesel engine performance and exhaust emission

Pomegranate peel carbon quantum dots were synthesized through a hydrothermal process. This innovative green nanoparticle underwent characterization using UV–visible spectroscopy, TEM, FT-IR, XRD, CHN, and N2 adsorption–desorption isotherms. The effects of pomegranate peel carbon quantum dots on greenhouse gas emissions from diesel engines and the efficiency of diesel engines were assessed by utilizing wasted frying oil biodiesel with a B20 volumetric concentration. Different concentrations of pomegranate peel CQDs (100, 300, and 600ppm) were tested for each fuel blend. The results indicated that when compared to D100 fuel, the optimal concentration of carbon quantum dots (600 ppm) led to significant improvements in torque, power, CO, UHC, and NOx levels by 12.113 %, 18.606 %, 14.12 %, 33.85 %, and 26 %, respectively. Furthermore, the oxidation stability of biodiesel was examined using the Rancimat technique, revealing that biodiesel derived from wasted frying oil exhibited low oxidation stability (6 h). To enhance the stability, three antioxidants were tested: pomegranate peel carbon quantum dot, synthetic antioxidant BHA, and alcoholic extract of pomegranate peel. Accelerated tests using the Rancimat technique demonstrated a substantial increase in the storage stability of wasted sunflower oil biodiesel when mixed with pomegranate peel carbon quantum dot (92.21 h), BHA (36.5 h), and alcoholic extract of pomegranate peel (12.48 h) at a concentration of 7000 ppm. Overall, these findings suggest that pomegranate peel carbon quantum dots serve as effective antioxidants for biodiesel and as alternative fuel additives to enhance diesel exhaust emissions and engine efficiency.