Sorption of chlorinated benzenes on alluvial clays beneath a landfill site

Sorption of hydrophobic contaminants commonly present in landfill leachates (chlorobenzene, 1,4-dichlorobenzene and 1,2,4-trichlorobenzene) onto alluvial clays was studied by means of batch experiments. The alluvial clays, which constitute a naturally occurring low permeability barrier to leachate migration, were physically, chemically and mineralogically characterised. Sorption isotherms of chlorobenzene and 1,2,4-trichlorobenzene were adequately described by a linear model while 1,4-dichlorobenzene isotherm showed an appreciable non-linearity. 1,2,4-trichlorobenzene was found to be the compound most retained in the clay, followed by 1,4-dichlorobenzene and then chlorobenzene. The increased sorption of chlorobenzene with the organic carbon content of the alluvial clays indicates that sorption is controlled by the naturally occurring organic carbon. The sorption coefficients obtained in this study were up to 5 times smaller than the values calculated using empirical correlations and values typically reported for sediment and soil samples. This suggests a slightly less lipophilic character of the organic matter in the alluvial clays. The sorption coefficients followed a linear relationship to the indicators of hydrophobicity of the chlorinated benzenes.

• INTRODUCTION

• MATERIALS AND METHODS

• RESULTS AND DISCUSSION

• CONCLUSIONS

• ACKNOWLEDGEMENTS

• REFERENCES