HENRY’S LAW CONSTANTS OF CYCLODEXTRIN-TCE SYSTEMS AT VARIOUS CONCENTRATION AND TEMPERATURE CONDITIONS

Non-aqueous phase liquids (NAPLs) are common ground water contaminants found at numerous sites. Cyclodextrin enhanced flushing of NAPL contaminated aquifers has been demonstrated a viable alternative to conventional remediation methods. However, the presence of cyclodextrin in solution complicates the chemical analysis of volatile organic compounds, such as trichloroethylene (TCE). It also requires more effort to air-strip the TCE from the cyclodextrin solution. The main reason for these complications is the presence of TCE in three instead of two phases, i.e., the aqueous solution, the vapor phase, and complexed inside the cyclodextrin molecule. We examined aqueous TCE-cyclodextrin systems at various concentration and temperature conditions and determined their respective Henry’s law constants. The presence of cyclodextrin in the system caused lower Henry’s law constants of TCE, which indicates that a higher fraction of TCE remained in the liquid phase. Also, our results provided a model for the Henry’s law constant of NAPLs in cyclodextrin solution at variable temperature conditions. This model can be used, for example, to better predict the distribution of volatile contaminants in the unsaturated zone during cyclodextrin flushing and to permit more accurate engineering of the cyclodextrin-air stripping process.