SREL Reprint #2912

Describing chlorophenol sorption on variable-charge soil using the triple-layer model

Mara Cea1, J.C. Seaman2, Alejandra A. Jara3, M.L. Mora3, and M.C. Diez4

1Universidad de La Frontera, P.O. Box 54-D, Temuco, Chile
2Savannah River Ecology Laboratory, The University of Georgia, Drawer E, Aiken, SC 29802, USA
3Departamento de Ciencias Químicas, Universidad de La Frontera, P.O. Box 54-D, Temuco, Chile
4Departamento de Ingeniería Química, Universidad de La Frontera, P.O. Box 54-D, Temuco, Chile

Abstract: The sorption of 2,4-dichlorophenol, 2,4,6-trichlorophenol, and pentachlorophenol by a variable-charge soil from southern Chile was studied in a series of batch experiments. The chlorophenol sorption behavior was evaluated as a function of pH (pH range 4–8) at two different ionic strengths, 0.01 and 0.1 M KCl (25 °C). Chlorophenol sorption depended on pH and a downward shift in the soil PZC was observed with increasing chlorophenol concentration. Chlorophenol sorption decreased with increasing pH, suggesting that the undissociated species is sorbed more readily and that electrostatic repulsion may inhibit partitioning as pH increases. Data from the sorption experiments were fitted by the triple-layer model, in which monodentate outer- and inner-sphere complexes were formed between deprotonated organic molecules and active sites on the variable-charge soil.

Keywords: Variable charge soil; Chlorophenol; Surface complexation modeling

SREL Reprint #2912

Cea, M., J. C. Seaman, A. A. Jara, M. L. Mora, and M. C. Diez 2005. Describing chlorophenol sorption on variable-charge soil using the triple-layer model. Journal of Colloid and Interface Science 292:171-178.

This information was provided by the University of Georgia's Savannah River Ecology Laboratory (srel.uga.edu).