Real-World Emissions and Formation Mechanism of IVOCs from Biodiesel-Fueled Agricultural Machinery

The use of biodiesel as an alternative to diesel remains controversial because of its potential impact on organic matter emissions. Herein, intermediate-volatility organic compounds (IVOCs) from five agricultural machines (AMs) using three types of fuels (pure diesel (B0), diesel mixed with 5 and 20% biodiesel (B5 and B20), respectively) were collected and analyzed. The following results were obtained: (1) Reasonable biodiesel ratios reduced IVOC emissions. The average emission factors of IVOCs (EF_IVOCs) of B5-fueled AMs were 485.8 ± 272.9 mg/kg fuel, 24.2% reduction from that of B0-fueled AMs. (2) The chemical compositions and secondary organic aerosol formation potentials (SOAFPs) of IVOCs changed during AMs fueled by different biodiesel blend ratios. The highest EF_IVOCs values for B5- and B20-fueled AMs were within the Bin12 interval. Consequently, the SOAFPs of n-alkanes for B5-fueled AMs were lower than those for B0. (3) The oxygen contents of B5 and B20 increased their combustion efficiency, and long-chain carbons in biodiesel were pyrolyzed and fragmented. However, high-viscosity biodiesel inhibited engine performance because more volatile organic matter was condensed and adsorbed on unburned fuel. In the future, some technologies should be developed to reduce the viscosity of biodiesel.