title: Evidence of micropore filling for sorption of nonpolar organic contaminants by condensed organic matter.
abstract: Although microporosity and surface area of natural organic matter (NOM) are crucial for mechanistic evaluation of the sorption process for nonpolar organic contaminants (NOCs), they have been underestimated by the N adsorption technique. We investigated the CO-derived internal hydrophobic microporosity () and specific surface area (SSA) obtained on dry samples and related them to sorption behaviors of NOCs in water for a wide range of condensed NOM samples. The is obtained from the total CO-derived microporosity by subtracting out the contribution of the outer surfaces of minerals and NOM using N adsorption-derived parameters. The correlation between or CO-SSA and fractional organic carbon content () is very significant, demonstrating that much of the microporosity is associated with internal NOM matrices. The average and CO-SSA are, respectively, 75.1 μL g organic carbon (OC) and 185 m g OC from the correlation analysis. The rigid aliphatic carbon significantly contributes to the microporosity of the Pahokee peat. A strong linear correlation is demonstrated between / and the OC-normalized sorption capacity at the liquid or subcooled liquid-state water solubility calculated via the Freundlich equation for each of four NOCs (phenanthrene, naphthalene, 1,3,5-trichlorobenzene, and 1,2-dichlorobenzene). We concluded that micropore filling ("adsorption") contributes to NOC sorption by condensed NOM, but the exact contribution requires knowing the relationship between the dry-state, CO-determined microporosity and the wet-state, NOC-available microporosity of the organic matter. The findings offer new clues for explaining the nonideal sorption behaviors of NOCs.
authors.forename: Yong
authors.initials: Y
authors.lastname: Ran
authors.forename: Yu
authors.initials: Y
authors.lastname: Yang
authors.forename: Baoshan
authors.initials: B
authors.lastname: Xing
authors.forename: Joseph J
authors.initials: JJ
authors.lastname: Pignatello
authors.forename: Seokjoo
authors.initials: S
authors.lastname: Kwon
authors.forename: Wei
authors.initials: W
authors.lastname: Su
authors.forename: Li
authors.initials: L
authors.lastname: Zhou
mesh_terms: D000327:Adsorption; D002244:Carbon / Q000737:chemistry; D012987:Soil; D012989:Soil Pollutants; D012995:Solubility
chemical_list: D012987:Soil; D012989:Soil Pollutants; D002244:Carbon