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Chemical factors influencing colloid-facilitated transport of contaminants in porous media

February 27, 1997

The effects of colloids on the transport of two strongly sorbing solutesa hydrophobic organic compound, phenanthrene, and a metal ion, Ni2+were studied in sand-packed laboratory columns under different pH and ionic strength conditions. Two types of column experiments were performed as follows:  (i) sorption/mobilization experiments where the contaminant was first sorbed in the column under conditions where no colloids were released and mobilized under conditions where colloids were released as a result of ionic strength reduction in the influent; and (ii) transport experiments where the contaminant, dissolved or sorbed on colloids, was injected into columns packed with a strongly sorbing porous medium. In the first type of experiment, contaminant mobilization was significant only when all releasable colloids were flushed from the column. In all other cases, although high colloid particle concentrations were encountered, there was no marked effect on total contaminant concentrations. In the second type of experiment, colloid deposition efficiencies were shown to control the enhancement of transport. The deposition efficiency was a function of the pH (for a high organic content sand) and of the contaminant concentration (for a charged species such as Ni2+).

Citation Information

Publication Year 1997
Title Chemical factors influencing colloid-facilitated transport of contaminants in porous media
DOI 10.1021/es9600643
Authors Sujoy B. Roy, David A. Dzombak
Publication Type Article
Publication Subtype Journal Article
Series Title Environmental Science & Technology
Index ID 70185300
Record Source USGS Publications Warehouse
USGS Organization Toxic Substances Hydrology Program