title: Matrix-immobilized organoclay for the sorption of polycyclic aromatic hydrocarbons and pentachlorophenol from groundwater.
abstract: Sorbent materials consisting of organoclay immobilized onto the surface of a solid support were evaluated for use in pentachlorophenol (PCP) and polycyclic aromatic hydrocarbon (PAH) remediation of groundwater at a creosote-contaminated Superfund site. Cetylpyridinium-exchanged low pH montmorillonite clay (CP-LPHM) was bonded to either sand (CP-LPHM/sand) or granular activated carbon (GAC) (CP-LPHM/GAC) using the free acid form of carboxymethylcellulose as an adhesive. Effluent from an oil-water separator was eluted through equal bed volumes of composite (4 g 3:2 CP-LPHM/GAC or 13 g CP-LPHM/sand), affinity-extracted, and quantitatively analyzed by GC/MS. PCP, naphthalene, fluorene, phenanthrene, pyrene, and total PAHs were initially reduced by both CP-LPHM/GAC (> or =99%, 61%, 99%, > or =99%, 97%, and 94%, respectively) and CP-LPHM/sand (90%, 70%, 94%, 95%, 93%, and 86%, respectively). Complete breakthrough of naphthalene occurred after approximately 15 h of elution through 3:2 CP-LPHM/GAC and 22 h through CP-LPHM/sand. PCP showed complete breakthrough following 18 h of elution through 3:2 CP-LPHM/GAC and 26 h through CP-LPHM/sand. However, 50% breakthrough was not attained for higher molecular weight PAHs, as fluoranthene, pyrene, benzo[a]anthracene, and chrysene continued to be greatly reduced with both 3:2 CP-LPHM/GAC (98%, 95%, 94%, and 95%, respectively) and CP-LPHM/sand (75%, 73%, 76%, and 78%, respectively) after 48 h of continuous elution. Results confirm prior studies, indicating that these organoclay-containing composites have a high capacity for contaminants found in wood preserving waste. Further, results suggest that the inclusion of CP-LPHM may be useful as part of an effective strategy for groundwater remediation of high concentrations of PCP and PAHs, in particular high molecular weight and carcinogenic PAHs.
authors.affiliation: Intercollegiate Faculty of Toxicology, Department of Veterinary Anatomy and Public Health, College of Veterinary Medicine, Texas A&M University, College Station, TX 77843-4458, USA.
authors.forename: Melinda C
authors.initials: MC
authors.lastname: Wiles
authors.forename: Henry J
authors.initials: HJ
authors.lastname: Huebner
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: McDonald
authors.forename: Kirby C
authors.initials: KC
authors.lastname: Donnelly
authors.forename: Timothy D
authors.initials: TD
authors.lastname: Phillips
mesh_terms: D000327:Adsorption; D001546:Bentonite / Q000737:chemistry*; D001673:Biodegradation, Environmental; D002266:Carboxymethylcellulose Sodium; D002594:Cetylpyridinium / Q000737:chemistry; D003902:Detergents / Q000737:chemistry; D004785:Environmental Pollutants / Q000032:analysis*; D005374:Filtration; D008401:Gas Chromatography-Mass Spectrometry; D010416:Pentachlorophenol / Q000737:chemistry* / Q000302:isolation & purification; D011084:Polycyclic Aromatic Hydrocarbons / Q000737:chemistry* / Q000302:isolation & purification; D014881:Water Supply / Q000032:analysis*
chemical_list: D003902:Detergents; D004785:Environmental Pollutants; D011084:Polycyclic Aromatic Hydrocarbons; D001546:Bentonite; D002594:Cetylpyridinium; D010416:Pentachlorophenol; D002266:Carboxymethylcellulose Sodium