Influences of Waste Cooking Oil-Based Biodiesel Blends on PAH and PCDD/F Emissions from Diesel Engines in Durability Testing Cycle

Abstract

In this study, the 60,000-km durability tests were performed on two diesel engines (EURO IV and EURO II) by using B10 (10% waste cooking oil + 90% diesel) and B8 (8% waste cooking oil + 92% diesel), respectively, to determine the impacts on the emissions of polycyclic aromatic hydrocarbons (PAHs) and polychlorinated dibenzo-p-dioxins and dibenzofurans (PCCD/Fs). The above emissions were measured per 20,000-km testing intervals. The highest total PAH mass concentrations were 38.2 and 25.6 μg Nm^(-3) before durability test by operating the EURO IV and II engines, respectively, and decreased 51-55% after 60,000-km operation. The dominant congeners of PAH emissions were naphthalene (＞ 45%), pyrene, and phenanthrene, which belonged to the LM-PAHs. The total PAH BaP_(eq) had different emission trends between the two engines during the durability tests. The highest level was 2.17 μg BaP_(eq) Nm^(-3) from EURO II engine before the test and reduced 84% after a 60,000-km cycle, when the total-BaP_(eq) emissions of EURO IV tended to increase from 0.0894 to 0.154 μg BaP_(eq) Nm^(-3) after the same test. The most dominant congener to the toxicity emissions was benzo(a)pyrene (~70%). Additionally, the PCDD/F emissions were tested in EURO IV engine by using B10. The PCDD/F concentrations of mass and toxicity approached the highest levels, 167 ng Nm^(-3) and 3.69 pg WHO-TEQ Nm^(-3), after 60,000-km and 20,000-km running cycles, respectively. The main dominant congeners were OCDD (＞ 50%) for mass, 2,3,7,8-TeCDD (＞ 35%) and 1,2,3,7,8- PeCDD (＞ 18%) for toxicity. Consequently, the use of WCO-biodiesel might reduce the PAH mass and toxicity emissions in older engine but had no significant effect in PAH and PCDD/F emissions during the deterioration of a newer engine.