Surfactant Foam Selection for Enhanced Light Non-Aqueous Phase Liquids (LNAPL) Recovery in Contaminated Aquifers

Foam is promising for the remediation of non-aqueous phase liquids (NAPL) source zones; however, the production of foam and its behavior in porous media are poorly understood. A methodology for the selection of surfactants suitable for foam production applied to NAPL remediation was developed. Two criteria were initially used for surfactant selection: foamability as evaluated by the Ross-Miles test and interfacial tension reduction measured with the pendant drop method. Three promising surfactants were identified and used in sand column tests: Genapol LRO because it produced the highest foam height in the Ross-Miles test, Ammonyx Lo which exhibited the lowest interfacial tension with p-xylene and had the second highest foam height, and Tomadol 900 because it showed intermediate results in both tests. Viscosity was found to be proportional to foamability. Genapol LRO produced a foam so viscous that it destabilized by the end of the experiment. Ammonyx Lo produced a less viscous foam but with a stable front. Tomadol 900 produced an unstable foam with poor viscosity. Results from column tests gave indications of optimal conditions needed to produce a stable and viscous foam front.