A molecular dynamics study of nanoparticle-formation from bioethanol-gasoline blend emissions

Aerosol components and nanoparticles deriving from fuel combustion represent a class of exhaust emissions with critical relevance to environmental studies. In particular, the formation of nanoparticles is an important theme for environmental assessments of new fuel blends. Here, a set of computer simulations is carried out to study the behaviour of acetaldehyde-phenanthrene nanoparticles in relation to the influences to the three major atmospheric components CO2, O-2, N-2. The results show that phenanthrene and acetaldehyde quickly generate nanoparticles with dimensions of 2-5 nm in vacuum. The formed particles are stable in atmospheric conditions and interestingly absorb CO2 from the atmosphere-gas simulations but not O-2 and N-2. The probability of absorption of CO2 in the formed nanoparticles results as 10-20-fold compared to N-2 and O-2. Furthermore, acetaldehyde appears to localize on the surface of the formed nanoparticles, and seemingly acts with the planar geometry of phenanthrene as a facilitator for CO2 absorption. The results provided show also the properties of formed nanoparticle with higher concentrations of acetaldehyde and lower of phenanthrene, where phenanthrene forms the core of the nanoparticle, while acetaldehyde interacts with the surface and subsurface area in making their chemistry hydrophilic with a dense aromatic core. The study is important for further assessing bioethanol and fuel blends, and also introduces a methodology for studying interactions of gases and particles at the molecular level, with macroscopic significance. The study reports on growth of nanoparticles by CO2 absorption, introduces a new issue for blending fuels, with implications towards pollution profiles. (C) 2016 Elsevier Ltd. All rights reserved.