title: Remediation of elemental mercury using in situ thermal desorption (ISTD).
abstract: In situ thermal desorption (ISTD) is a soil heating method that simultaneously applies heat and vacuum to the subsurface at temperatures up to 600 degrees C. As the soil is heated, the vapor pressure of the contaminant increases allowing mass transfer to the gas phase and extraction from the soil using vacuum wells. The overall goal of this research is to assess the feasibility of using ISTD to remove elemental mercury from soils. The initial phase of research included design of a laboratory soil column apparatus and preliminary soil column experiments with surrogate nonaqueous phase liquids (perfluorocarbons) to test the apparatus and investigate the effects of air flow rate and temperature on the ISTD process. Following the preliminary experiments, a mercury off-gas treatment system was added and mercury experiments were conducted. Experiments performed using elemental mercury showed greater than 99.8% removal of the mercury from Ottawa sand. These results show that ISTD can remove mercury from soil at temperatures well below its boiling point and that perfluorodecalin can be used as a surrogate for elemental mercury in laboratory experiments. A flow and transport simulator was used to model the results from both the perfluorocarbon and the mercury experiments.
authors.affiliation: Department of Civil, Architectural, and Environmental Engineering, ECJ 8.6, University of Texas, Austin, Texas 78712, USA.
authors.forename: Anna M
authors.initials: AM
authors.lastname: Kunkel
authors.forename: Jeremy J
authors.initials: JJ
authors.lastname: Seibert
authors.forename: Lucas J
authors.initials: LJ
authors.lastname: Elliott
authors.forename: Ricci
authors.initials: R
authors.lastname: Kelley
authors.forename: Lynn E
authors.initials: LE
authors.lastname: Katz
authors.forename: Gary A
authors.initials: GA
authors.lastname: Pope
mesh_terms: D005466:Fluorocarbons / Q000737:chemistry; D008628:Mercury / Q000302:isolation & purification*; D013696:Temperature
chemical_list: D005466:Fluorocarbons; D008628:Mercury