Emissions of particulate-bound elements from biodiesel and ultra low sulfur diesel: Size distribution and risk assessment

► Particulate emissions from diesel, biodiesel and their blends were characterized. ► More ultrafine particles were emitted from biodiesel compared to those from diesel. ► Toxic elements (Zn, Cr and Ni) were present in higher concentrations in biodiesel exhaust. ► A significant proportion of these elements was found in ultrafine particles. ► Exposure to particulate emissions from waste cooking oil-derived biodiesel exhaust is of health concern.

Use of waste cooking oil derived biodiesel (WCOB) as an alternative fuel in diesel engines has increased significantly in recent years. The impact of WCOB on particulate emissions from diesel engines needs to be investigated thoroughly. This study was conducted to make a comparative evaluation and size-differentiated speciation of the particulate bound elements from ultra low sulfur diesel (ULSD) and WCOB and a blend of both of the fuels (B50). Particle mass and their elemental size distributions ranging from 0.01-5.6 μm were measured. It was observed that more ultrafine particles (UFPs, < 100 nm) were emitted when the engine was fueled with WCOB. Fifteen particulate-bound elements such as K, Al, Mg, Co, Cr, Cu, Fe, Mn, Cd, Ni, As, Ba, Pb, Zn and Sr were investigated and reported in this study. Potential health risk associated with these particulate bound elements upon inhalation was also evaluated based on dose-response assessments for both adults and children. The findings indicate that the exposure to PM of the B100 exhaust is relatively more hazardous and may pose adverse health effects compared to that of ULSD. Also, investigations on human health risk due to exposure to UFPs indicate that UFPs contribute a major fraction (>70%) of the total estimated health risk.