Modelling maximum adsorption capacities of soot and soot-like materials for PAHs and PCBs

P.C.M. van Noort, M.T.O. Jonker, A.A. Koelmans

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52 Citations (Scopus)

Abstract

Recent studies have shown that not partitioning but adsorption is the main mechanism for sorption of hydrophobic organic compounds to soot and soot-like materials. For compounds that adsorb by van der Waals forces only, variation in soot-water distribution coefficients will result from differences in these forces for adsorption, as well as the maximum number of accessible sites. This maximum number of accessible sites may a priori be expected to vary due to differences in both sorbent characteristics and sorbate dimensions. In this modeling study, variation in maximum adsorption capacities is explained from sorbent and sorbate properties. Maximum adsorption capacities were calculated using (a) literature values for soot-water distribution coefficients for polycyclic aromatic hydrocarbons and polycholorobiphenyls on 10 different soot and soot-like materials and (b) Langmuir affinities for adsorption at a carbonaceous surface estimated using a recently reported method
Recent studies have shown that not partitioning but adsorption is the main mechanism for sorption of hydrophobic organic compounds to soot and soot-like materials. For compounds that adsorb by van der Waals forces only, variation in soot-water distribution coefficients will result from differences in these forces for adsorption, as well as the maximum number of accessible sites. This maximum number of accessible sites may a priori be expected to vary due to differences in both sorbent characteristics and sorbate dimensions. In this modeling study, variation in maximum adsorption capacities is explained from sorbent and sorbate properties. Maximum adsorption capacities were calculated using (a) literature values for soot-water distribution coefficients for polycyclic aromatic hydrocarbons and polychlorobiphenyls on 10 different soot and soot-like materials and (b) Langmuir affinities for adsorption at a carbonaceous surface estimated using a recently reported method. The variation in maximum adsorption capacities could be explained by the variation in sorbent specific surface area, sorbent organic carbon content, and the sorbent-sorbate contact area. Furthermore, increasing sorbate thickness was related to a decrease in maximum adsorption capacities, which points to adsorption in micropores. Maximum adsorption capacities decreased by 1-2 orders of magnitude as the contact area increased by 50%. This points to adsorption sites being hardly larger than sorbates.
Original languageEnglish
Pages (from-to)3305-3309
JournalEnvironmental Science and Technology
Volume38
Issue number12
DOIs
Publication statusPublished - 2004

Keywords

  • aromatic hydrocarbons
  • polycyclic hydrocarbons
  • adsorption
  • sorbates
  • hydrophobicity
  • organic compounds
  • monitoring
  • water quality
  • water bottoms
  • polycyclic aromatic-hydrocarbons
  • hydrophobic organic-chemicals
  • partition-coefficients
  • aqueous solubilities
  • black carbon
  • sorption
  • water
  • sediment
  • extraction
  • biphenyls

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