title: Quantitative high-resolution mapping of phenanthrene sorption to black carbon particles.
abstract: Sorption of hydrophobic organic contaminants such as polycyclic aromatic hydrocarbons (PAHs) to black carbon (BC) particles has been the focus of numerous studies. Conclusions on sorption mechanisms of PAH on BC were mostly derived from studies of sorption isotherms and sorption kinetics, which are based on batch experiments. However, mechanistic modeling approaches consider processes at the subparticle scale, some including transport within the pore-space or different spatial pore-domains. Direct evidence based on analytical techniques operating at the submicrometer scale for the location of sorption sites and the adsorbed species is lacking. In this work, we identified, quantified, and mapped the sorption of PAHs on different BC particles (activated carbon, charcoal and diesel soot) on a 25-100 nm scale using scanning transmission X-ray microscopy (STXM). In addition, we visualized the pore structure of the particles by transmission electron microscopy (TEM) on the 1-10 nm-scale. The combination of the chemical information from STXM with the physical information from TEM revealed that phenanthrene accumulates in the interconnected pore-system along primary "cracks" in the particles, confirming an adsorption mechanism.
authors.affiliation: Center for Applied Geoscience, Eberhard Karls University Tuebingen, Hölderlinstr 12, 72074 Tuebingen, Germany.
authors.forename: Martin
authors.initials: M
authors.lastname: Obst
authors.forename: Peter
authors.initials: P
authors.lastname: Grathwohl
authors.forename: Andreas
authors.initials: A
authors.lastname: Kappler
authors.forename: Oliver
authors.initials: O
authors.lastname: Eibl
authors.forename: Nicola
authors.initials: N
authors.lastname: Peranio
authors.forename: Tilman
authors.initials: T
authors.lastname: Gocht
mesh_terms: D000327:Adsorption; D002244:Carbon / Q000737:chemistry*; D017348:Microscopy, Electron, Scanning Transmission; D010316:Particle Size; D010616:Phenanthrenes / Q000737:chemistry*; D011084:Polycyclic Aromatic Hydrocarbons / Q000737:chemistry; D012989:Soil Pollutants / Q000737:chemistry*; D053260:Soot / Q000737:chemistry*; D001335:Vehicle Emissions
chemical_list: D010616:Phenanthrenes; D011084:Polycyclic Aromatic Hydrocarbons; D012989:Soil Pollutants; D053260:Soot; D001335:Vehicle Emissions; C031181:phenanthrene; D002244:Carbon