Quantitative structure‐activity relationships for evaluating the influence of sorbate structure on sorption of organic compounds by soil

Qinhong Hu, Xiaojiang Wang, Mark L. Brusseau

Research output: Contribution to journalArticlepeer-review

27 Scopus citations

Abstract

The purpose of this work was to investigate the effect of sorbate structure, by using the quantitative structure‐activity relationship (QSAR) approach, on sorption of organic compounds by two soils with different amounts of organic matter. Miscible displacement experiments were performed with several organic contaminants representing six classes of nonpolar, nonionizable organic chemicals, including chlorinated aliphatics, chlorobenzenes, polycyclic aromatic hydrocarbons (PAHs), n‐alkylbenzenes, methylated benzenes, and polychlorinated biphenyls (PCBs). The breakthrough curves were analyzed by using a bicontinuum model wherein sorption is assumed to be instantaneous for a fraction of the sorbent and rate limited for the remainder. The QSAR approach was used to investigate the dependency of both equilibrium and nonequilibrium sorption coefficients on topological descriptors representing structural properties of the solutes. For both equilibrium and nonequilibrium parameters, the first‐order valence molecular connectivity (1Xv) was found to be the best topological descriptor. Most of the rate‐limited sorption behavior could be explained by accounting for the size and structure of the solute molecule, as indicated by the good correlation between the rate coefficient and 1Xv. This supports the contention that rate‐limited sorption in these systems is controlled by a physical diffusion mechanism, consistent with the polymer diffusion model. Based on this model, the calculated diffusion‐length ratios for the Borden and Mt. Lemmon soils, which have a large difference in organic‐matter contents, compare favorably to the values determined from the measured rate data.

Original languageEnglish (US)
Pages (from-to)1133-1140
Number of pages8
JournalEnvironmental Toxicology and Chemistry
Volume14
Issue number7
DOIs
StatePublished - Jul 1995

Keywords

  • Organic compounds
  • QSAR
  • Solute structure
  • Sorption

ASJC Scopus subject areas

  • Environmental Chemistry
  • Health, Toxicology and Mutagenesis

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