Impact of DNAPL contact on the structure of smectitic clay materials.
Smectitic clays have a flexible structure that may be impacted by contact with dense nonaqueous phase liquids (DNAPLs) present at hazardous waste sites. Measurements of the basal spacing of air-dry clays contacted with pure chlorinated solvents and chlorinated DNAPL wastes showed that the intraparticle spacing is similar to that in air. Basal spacings of water-saturated clays contacted with pure chlorinated solvents are similar to those in contact with water, even after extended equilibration times (300 d). In contrast, contact with chlorinated DNAPL wastes reduced the basal spacing of water-saturated sodium smectites in a relatively short time frame, resulting in cracks that were as large as 1mm in aperture. The penetration of these wastes into the intraparticle spacing of clay and the resultant cracking may contribute to the accumulation of chlorinated compounds in clay layers observed in the field and the extended remediation times associated with this mass storage.
Environmental and Water Resources Engineering, 1351 Beal Ave., University of Michigan, Ann Arbor, MI 48109-2125, United States.
Derya
D
Ayral
Margarita
M
Otero
Mark N
MN
Goltz
Avery H
AH
Demond
D000538:Aluminum Silicates / Q000737:chemistry; D000077215:Clay; D008956:Models, Chemical; D017640:Silicates / Q000737:chemistry*; D012997:Solvents / Q000737:chemistry; D013750:Tetrachloroethylene / Q000737:chemistry*; D014241:Trichloroethylene / Q000737:chemistry*; D064091:Waste Disposal Facilities; D014874:Water Pollutants, Chemical / Q000737:chemistry*
D000538:Aluminum Silicates; D017640:Silicates; D012997:Solvents; D014874:Water Pollutants, Chemical; D014241:Trichloroethylene; C033214:Smectite; D000077215:Clay; D013750:Tetrachloroethylene
Basal spacing; Chlorinated organic solvents; Clay; DNAPL; Hazardous waste; X-ray diffraction