Use of Cationic Surfactants to Modify Aquifer Materials to Reduce the Mobility ofHydrophobic Organic Compounds. Environmental Research Brief

摘要

Cationic surfactants can be used to modify surfaces of soils and subsurfacematerials to promote sorption of hydrophobic organic compounds (HOC) and retard their migration. Batch and column experiments were performed to investigate these phenomena. The cationic surfactant was dodecylpyridinium (DP); the HOC were chlorobenzene homologs; competing metal ions were Pb(2+), Cd(2+), and Cu(2+); and sorbents were low-organic-carbon aquifer materials (Lula, EPA-12, Borden Sand) and pristine minerals (kaolinite, montmorillonite). The investigation covered three major topics (1) adsorption of DP to particle surfaces; (2) sorption of chlorobenzenes to DP-modified surfaces; and (3) adsortion competition between DP and the metal ions. The adsorption isotherms of DP were distinctly nonlinear, even at very low surface concentrations. A multisite adsorption model was developed to describe adsorption over a wide range of DP, NaCl, and CaCl2 concentrations. Two types of adsorption reactions were found to be significant; exchange of DP with a alkali-metal cation, and adsorption of pyridinium with chloride counter-ion.