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National Institute of Environmental Health Sciences

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Your Environment. Your Health.

Final Progress Reports: Texas A&M University: Chemical Intervention Strategies

Superfund Research Program

Chemical Intervention Strategies

Project Leader: Timothy D. Phillips
Grant Number: P42ES004917
Funding Period: 2000-2008
View this project in the NIH Research Portfolio Online Reporting Tools (RePORT)

Project-Specific Links

Final Progress Reports

Year:   2007  2004 

Previous research in this laboratory has shown that multifunctional clays can be tightly immobilized onto the surface of a solid support.  These porous composite sorbents are effective in the removal of toxic contaminants from groundwater.  In recent studies, several new composite sorbent materials were developed and tested to determine their effectiveness in the remediation of pentachlorophenol (PCP) and a variety of PAHs.  These included:  1) cetylpyridinium (CP) electrostatically bonded to sand; 2) CP-exchanged low pH montmorillonite clay (CP-LPHM) bonded to sand using the free acid form of carboxymethylcellulose (H-CMC) as an adhesive; 3) CP-LPHM bonded to granular activated carbon (GAC) using H-CMC as an adhesive; and 4) CP-LPHM bonded to silica beads using chitosan as an adhesive.  In addition, a commercially available product was also tested.  Field testing was conducted at a creosote-contaminated Superfund site in the northwestern United States.  Identical glass columns were filled with a volume of composite sorbent equal to that of 5 g of GAC and covered with sand and glass wool.  Effluent from an oil-water separator (OWS) was continuously eluted through the columns over a minimum of 20 h and collected as 1 L samples.   After 27 h of continuous flow, CP-LPHM bonded to sand reduced the contaminant load of phenanthrene from 16,731 ± 3,268 to 755 ± 270 ng/L and pyrene from 886 ± 416 to 19 ± 4 ng/L, while CP-LPHM bonded to GAC reduced phenanthrene to 2113 ± 938 and pyrene to 46 ± 15 ng/L.  Over the same time period, continuous flow through dried chitosan gel beads showed reduction in phenanthrene from 50,099 ± 8,179 to 1,800 ± 901 ng/L and pyrene from 983 ± 268 to 44 ± 13 ng/L.  The results demonstrate that although CP-LPHM-based composites are effective for PAH removal, they are more effective for those PAHs with higher molecular weights.  Given the extremely high concentrations, the composites were also very effective at removing PCP at this site.  Therefore, a composite of CP-LPHM bonded to silica beads with chitosan or bonded to sand with H-CMC may be useful as a pre-polishing step prior to GAC treatment, as part of an effective strategy for reducing high concentrations of PAHs and PCP in groundwater.  Pilot testing of this technology is tentatively planned for the summer of 2005.

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