PAH emission from a gasoline-powered engine

A gasoline powered engine operated on a dynamometer was used to investigate the PAH (Polycyclic Aromatic Hydrocarbons) emission. A 95-leadfree gasoline (95-LFG) and a premium leaded gasoline (PLG) were used as power-fuels. The engine was simulated for the idling condition and for the cruising speeds at 40, 80 and 110 km/hr. The concentrations of 21 individual PAHs in the engine exhaust, gasolines, and the ambient air were determined. Engine exhaust samples were collected by a PAH sampling system, while the ambient air sample was collected by using a standard PS-1 sampler. Twenty one individual PAHs were analyzed primarily by a gas chromatography/mass spectrometer (GC/MS). Naphthalene (Nap) has the highest concentration in the liquid phase of both 95-LFG and PLG, in which it accounts for respectively 98.3% and 76.6% of the total PAH. In term of the mean fraction of the total PAHs entering the 95-LFG and PLG engines, the ambient air contributed less than 0.108% and 0.012%, respectively. Gasoline is the major PAH supplier for the automobile engine. By monitoring the PAH output/input mass ratios, the fuel combustion was found to be a generation process for ii PAHs - Flu, Ant, FL, Pyr, CYC, Bag CI-IR, BbF, BkF, BaP and BeP; and a depletion process for the rest 10 PAHs - Nap, AcPy, Acp, Pq PER, MD, DBA BbC, BghiP and COR, in both 95-LFG and PLG powered engines. The mean emission factors of BaP were 2.92 and 2.47 mu g/km for 95-LFG and PLG powered engines, respectively.