Polychlorinated dibenzo-p-dioxins (PCDDs) and certain polyaromatic hydrocarbons (PAHs) pose significant risks for humans due to their carcinogenic and mutagenic properties. Sorption processes are dominant for these solutes because of their low aqueous solubility.  Recent years have shown that black carbon is a potentially dominant phase in the attenuation of hydrophobic organic contaminants with sorption coefficients several orders of magnitude greater than those for partitioning into amorphous organic carbon.  In this study, aqueous sorption of two classes of solutes (PCDDs and PAHs) on black carbon and related 'contrasting' geosorbents is presented.  Solutes included PCDDs (dibenzo-p-dioxin and two chlorinated congeners) and naphthalene as a representative PAH.  Geosorbents included Cs-saponite, a muck soil, an organoclay, and granular activated carbon (GAC).  In addition to aqueous sorption isotherms, vibrational spectroscopy and molecular dynamics simulations were used to explore the mechanisms of surface interaction. The weakly hydrated clay minerals showed a higher-than-expected affinity of PCDDs and a considerably lower affinity for naphthalene.  In contrast, naphthalene showed a surprisingly high affinity for GAC despite the fact that it had the greatest aqueous solubility of the solutes studies.  Sorption mechanisms of the two solute classes on the four geosorbents are examined in this study.

Spectroscopic, molecular dynamics and sorption studies of PCDDs and PAHs interactions with black carbon and contrasting geosorbents

246th National Meeting (2013)

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