Aromatic hydrocarbons emissions in diesel and biodiesel exhaust

Regulated emissions of biodiesel blends are reasonably well documented in several works, non-regulated emissions, on the contrary, lack research. In this work, mono- and polycyclic aromatic hydrocarbons (MAHs and PAHs, respectively) emission tests were performed with a heavy-duty diesel engine, fueled with pure diesel (D) and biodiesel blends (v/v) of 2% (B2), 5% (B5) and 20% (B20%). The main objective of this study is to investigate the effect of the biodiesel addition on the emission profile of MAHs and PAHs. The tests were conducted using a six cylinder heavy-duty engine, typical of the Brazilian fleet of urban buses, in a steady-state condition under 1500 rpm. The PAHs were sampled with Teflon filters and XAD-2 cartridges and were identified by gaseous chromatograph coupled to a mass spectrometer (GC/MS) and quantified by flame ionization detection (GC/FID). The MAHs were sampled with active charcoal cartridges and analyzed by GC/FID. Both MAHs and PAHs filters and cartridges were extracted with dichloromethane in an ultrasonic bath. Ten PAHs and eight MAHs were identified and the average reduction of MAHs was 4.2% (B5), 8.2% (B5), and 21.1% (B20). The average reduction for PAHs was 2.7% (B2), 6.3% (B5), and 17.2% (B20). However, some PAHs and MAHs emissions increased because of/due to the biodiesel blends like phenanthrene, ethyl benzene, and trimethyl benzenes.