Abstract:
Surfactant phase behavior data are presented for dense nonaqueous phase liquids (DNAPLs).
The experimental procedures and results published in this paper led to the successful
selection of a surfactant formulation that was used in a field demonstration at a site
contaminated with DNAPL rich in trichloroethene (TCE). Experiments were conducted to
investigate the effects of temperature, electrolyte, cosolvent, xanthan gum polymer and
surfactant hydrophobe length on surfactant phase behavior. Experimental results are
presented for a field degreasing solvent that is a DNAPL from Operable Unit 2 (OU2) of
Hill Air Force Base, Utah. These experiments show that procedures previously developed
and reported only for pure component DNAPLs such as TCE can be useful for selecting
suitable surfactants for complex field DNAPLs. In addition to the usual criteria of
large increases in contaminant solubilization and lowering of interfacial tensions, we
identify rapid formation of microemulsions with acceptably low viscosities as an
additional requirement for surfactant screening. Our results indicate that the best
surfactant formulations equilibrate to low viscosity microemulsions within a few hours.
Extensive soil column studies have shown that such behavior leads to DNAPL recoveries
exceeding 99% without significant problems such as pore plugging and high surfactant
retention.
Reference:
V. Dwarakanath, and G.A. Pope, "Surfactant Phase Behavior with Field Degreasing
Solvent," Environmental Science & Technology, 34 (22) 4842, 2000.
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Last updated: April 25, 2002