Sorption of polyaromatic compounds by organic matter-coated Ca2+- and Fe3+-montmorillonite

Tamara Polubesova, Yona Chen, Catalin Stefan, Michael Selle, Peter Werner, Benny Chefetz*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

8 Scopus citations

Abstract

Sorption of organic contaminants to soil is of growing concern due to the potential risk associated with their persistence in soil and leaching to groundwater. The objective of this study was to evaluate sorption of non-polar (phenanthrene and pyrene) and polar (1-naphthol) polyaromatic compounds on montmorillonite saturated with either Ca2+ or Fe3+ and coated with natural organic matter, i.e. humic acid (HA), or cuticular waxes. The amount of carbon in both wax and HA-coated montmorillonite was greater for Fe3+-montmorillonite than for Ca2+-montmorillonite. For all systems, the order of sorption affinities was: pyrene > phenanthrene > 1-naphthol, corresponding to the order of their hydrophobicity. The HA-clay complexes adsorbed 80 to 93% of the added amounts of phenanthrene and pyrene. Sorption affinities (KOC) of phenanthrene and pyrene to HA-clay were higher than those to wax-clay for all tested systems. In contrast to the HA-clay systems, cation did not significantly affect affinity of phenanthrene to wax-clay surfaces. Sorption of polar 1-naphthol was significantly affected by the type of exchangeable cation. For Ca2+-clays, sorption of 1-naphthol was higher on wax-montmorillonite than on HA-montmorillonite. The opposite trend was observed for Fe3+-montmorillonite. Calculations eliminating sorbate-water interactions suggested similar changes in chemical potential of molecules of phenanthrene and pyrene upon transfer from pure liquid phase to sorbent, and that neither phenanthrene nor pyrene crystallized during its sorption.

Original languageAmerican English
Pages (from-to)36-41
Number of pages6
JournalGeoderma
Volume154
Issue number1-2
DOIs
StatePublished - 15 Dec 2009

Bibliographical note

Funding Information:
This research was supported by the Young Scientists Exchange Program (YSEP) of the German Federal Ministry of Education and Research (BMBF) in the framework of German–Israeli Cooperation in Water Technology Research.

Keywords

  • Exchangeable cations
  • Humic acid
  • PAH
  • Plant cuticle
  • Waxes

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