PARENT SESSION
SA6 - Sorption of Hydrophobic Pollutants
Chair: Koelmans, Albert Bart1, 1 P.O. Box 8080, Wageningen, Wageningen, The Netherlands
8:00 AM to 12:00 PM - Sunday, 17 November 2002
Room Ballroom B
(056) Carbon-immobilized organoclay for the removal of toxic contaminants from groundwater.
Wiles, Melinda*,1, Ake, Charles1, Phillips, Timothy1, Donnelly, Kirby1, Burghardt, Robert1, Autenrieth, Robin1, McDonald, Thomas1, 1 Texas A&M University, College Station, Texas, USA
ABSTRACT- Previous research in this laboratory has shown that multifunctional clays can be tightly immobilized onto the surface of a solid support. These porous composite materials are effective in the removal of toxic contaminants from groundwater. In this study, cetylpyridinium-exchanged low pH montmorillonite clay (CP-LPHM) was bonded to granular activated charcoal (GAC) at 5%, 10%, and 20% concentrations of clay by weight. Bench studies were conducted to determine bedlife by combining varying amounts of CP-LPHM/GAC composite with lab-generated, creosote-contaminated water. Water samples were extracted by affinity using a binary solid phase and quantitatively analyzed by GC/MS. These initial studies suggest that 10% coverage of GAC with CP-LPHM is required for maximum binding of polycyclic aromatic hydrocarbons (PAHs). Field studies were conducted at a creosote-contaminated Superfund site in the northwestern United States using identical glass columns packed with 10 g and 20 g amounts of each composite. Effluent from an oil-water separator was continuously eluted through the columns containing CP-LPHM/GAC composite over a 7-hour period and collected as 1 L samples. These samples were extracted and analyzed by affinity as described above and quantitatively analyzed for pentachlorophenol (PCP) and PAHs by GC/MS. At all concentrations of clay tested, the CP-LPHM/GAC composite reduced the contaminant load of total PAHs from a maximum of 9,000 ppb to <15 ppb. PCP was reduced from a maximum of 1,665 ppb to <32 ppb. These results demonstrate that immobilization of clay onto GAC as a solid support can be an effective strategy for reducing high concentrations of PAHs and PCP in groundwater. (Supported by NIEHS P42-ES04917 and TAES H6215.)
Key words: organoclay, carbon , composite, groundwater