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Environ Sci Technol

Title:		Hindered gas-phase partitioning of trichloroethylene from aqueous cyclodextrin systems: implications for treatment and analysis
Author(s):		Kashiyama N; Boving TB;
Address:		"Department of Geosciences, University of Rhode Island, Kingston, Rhode Island 02881, USA"
Journal Title:		Environ Sci Technol
Year:		2004
Volume:		38
Issue:		16
Page Number:		4439 - 4444
DOI:		10.1021/es049956q
ISSN/ISBN:		0013-936X (Print) 0013-936X (Linking)
Abstract:		"Chemically enhanced flushing has shown great promise for attenuating subsurface nonaqueous phase liquid (NAPL) contamination. One particular chemically enhanced remediation technology is cyclodextrin enhanced flushing (CDEF). CDEF has been demonstrated as a viable alternative to conventional and innovative remediation methods. However, the presence of cyclodextrin (CD) in solution complicates the treatment and analysis of volatile organic compounds, such as trichloroethylene (TCE). The principal reason for the complications is the presence of TCE in three compartments instead of two, i.e., the aqueous solution, the vapor phase, and complexed inside the soluble CD molecule. Aqueous TCE-CD systems were examined at various concentration and temperature conditions and their respective Henry's law constants were measured. The presence of CD significantly decreased Henry's law constant of TCE. On the basis of these results, a quantitative model was developed to predict the additional effort that becomes necessary when air-stripping TCE from CDEF flushing solution. The modeling results demonstrate that the presence of CD requires significantly higher gas flow rates or longer residence times of the flushing solution inside an air stripper. Similarly, current gas chromatographic purge-and-trap methods for TCE analysis in CD solution appear to underestimate the aqueous phase TCE concentration if the CD concentration of the sample is not accounted for. Although this model was developed specifically for CD-TCE systems, it is likely that these results have implications for other VOCs and other solubilization enhancing agents, such as surfactants or cosolvents"
Keywords:		"Cyclodextrins/*chemistry *Models, Theoretical Solubility Solvents/*chemistry/isolation & purification Temperature Trichloroethylene/*chemistry/isolation & purification Volatilization;"
Notes:		"MedlineKashiyama, N Boving, T B eng Research Support, Non-U.S. Gov't 2004/09/24 Environ Sci Technol. 2004 Aug 15; 38(16):4439-44. doi: 10.1021/es049956q"