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J Contam Hydrol

Title:		Experimental method for characterizing CVOC removal from fractured clays during boiling
Author(s):		Liu X; Tan T; Falta RW; Murdoch LC;
Address:		"Department of Environmental Engineering and Earth Sciences, Clemson University, Clemson, SC 29634-0905, USA. lxlttb@gmail.com"
Journal Title:		J Contam Hydrol
Year:		2013
Volume:		20130627
Issue:
Page Number:		44 - 59
DOI:		10.1016/j.jconhyd.2013.06.006
ISSN/ISBN:		1873-6009 (Electronic) 0169-7722 (Linking)
Abstract:		"Conventional remediation methods that rely on contact with contaminants can be ineffective in fractured media, but thermal methods of remediation involving CVOC stripping at boiling temperature show promise. However, limited experimental data are available to characterize thermal remediation because of challenges associated with high temperature. This research reports an experimental method using uniformly contaminated clay packed into two types of experimental cells, a rigid-wall stainless steel tube and a flexible-wall Teflon tube in a pressurized chamber. Both tubes are 5 cm in diameter and approximately 25 cm long. This laboratory apparatus was developed as a 1D physical model for contaminant transport in a cylindrical matrix towards a fracture, which is represented by one end of the cylinder and serves as the outlet of vapor and contaminant. The clay was contaminated with dissolved 1,2-dichloroethane (DCA) and bromide, and the columns were heated to more than 100 degrees C and then the top end was depressurized to atmospheric pressure to induce boiling. The outflow was condensed and analyzed for contaminant mass. The flexible-wall cell was confined to 100 kPa (gage), allowing equilibrium boiling temperatures of approximately 120 degrees C to be maintained. The clay was sampled before and after heating and extracted to determine the DCA distribution along the length of the column. During a typical test in the rigid-wall cell, internal temperatures and pressures along the column during heating reached the saturated vapor pressure curve. DCA concentrations in the recovered condensate were up to 12 times of the initial pore concentration in the clay. Less than 5% of non-volatile bromide was recovered. Significant removal of DCA and water occurred along the entire length of the clay column. This suggests that boiling was occurring in the clay matrix"
Keywords:		"Aluminum Silicates/*chemistry Clay Hot Temperature Hydrocarbons, Chlorinated/*chemistry Volatile Organic Compounds/*chemistry Boiling Chlorinated volatile organic compound (CVOC) Fractured clay Thermal remediation;"
Notes:		"MedlineLiu, Xiaoling Tan, Tianwu Falta, Ronald W Murdoch, Lawrence C eng Research Support, U.S. Gov't, Non-P.H.S. Netherlands 2013/07/23 J Contam Hydrol. 2013 Sep; 152:44-59. doi: 10.1016/j.jconhyd.2013.06.006. Epub 2013 Jun 27"