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J Hazard Mater

Title:		Slow desorption of volatile organic compounds from soil: evidence of desorption step limitations
Author(s):		Raihala TS; Wang Y; Jackman AP;
Address:		"Department of Chemical Engineering and Materials Science, University of California, Davis 95616-5294, USA"
Journal Title:		J Hazard Mater
Year:		1999
Volume:		65
Issue:		3
Page Number:		247 - 265
DOI:		10.1016/s0304-3894(98)00266-0
ISSN/ISBN:		0304-3894 (Print) 0304-3894 (Linking)
Abstract:		"Transient adsorption and desorption of 1,2 dichloroethane and toluene on dry Yolo silt loam soil were studied by continuously measuring the composition of the effluent from a soil-packed chromatography column with a mass spectrometer. After obtaining complete breakthrough at approximately 30% relative saturation of one chemical in nitrogen, pure nitrogen feed was initiated and maintained for several hours. Of the material adsorbed at breakthrough, 9.7% of the 1,2 dichloroethane and 14.2% of the toluene were highly resistant to desorption and remained sorbed on the soil even after 5 h of nitrogen flow. When a second chemical with a higher adsorption affinity was introduced into the soil column (water following toluene or toluene following 1,2 dichloroethane), the majority of the first chemical was quickly desorbed and began leaving the soil column before breakthrough of the second chemical. Conversely, when a second chemical with a smaller adsorption affinity was introduced into the soil column, only a small amount of the first chemical was displaced and began leaving the soil column after breakthrough of the second chemical. The results of this study indicate that the desorption step itself may be the rate-limiting step for sorbate which remains after prolonged exposure to sorbate-free gas"
Keywords:		Adsorption Ethylene Dichlorides/*analysis/chemistry Gas Chromatography-Mass Spectrometry Partial Pressure Soil/*analysis Time Factors Toluene/*analysis/chemistry Water;
Notes:		"MedlineRaihala, T S Wang, Y Jackman, A P eng 2 P42 ES04699/ES/NIEHS NIH HHS/ Research Support, U.S. Gov't, P.H.S. Netherlands 1999/05/25 J Hazard Mater. 1999 Mar 19; 65(3):247-65. doi: 10.1016/s0304-3894(98)00266-0"