Single-phase microemulsification of a complex light-nonaqueous-phase-liquid: Laboratory evaluation of several mixtures of surfactant/alcohol solutions

Journal Article · Sun Aug 01 04:00:00 EDT 1999 · Journal of Environmental Quality

DOI:https://doi.org/10.2134/jeq1999.00472425002800040012x· OSTI ID:20012696

Rhue, R D; Rao, P S.C.; Annable, M D

A recent advance in conventional pump-and-treat technology for aquifer remediation involves the use of surfactant-alcohol mixtures that will form a clear, transparent, thermodynamically stable oil-in-water microemulsion on contact with a residual non-aqueous-phase-liquid (NAPL). An initial screening of 86 commercial-grade surfactants for aqueous solubility resulted in selection of 58 that were further tested in batch experiments to evaluate the capacity to solubilize a complex NAPL waste collected from a Superfund site (Operable Unit OU-1) at Hill AFB, UT. The selected group of 58 surfactants represented six classes of anionic, nine classes of nonionic, and one class of amphoteric surfactants. Batch studies on NAPL solubilization identified a number of surfactants suitable for use in the field demonstration phase of the project; a further criterion in surfactant selection was that the flushing solution had a viscosity <2 cp. The best surfactants among this group had HLB (hydrophilic-lipophilic balance) values between 12 and 13, and solubilized 10 to 20 g L{sup {minus}1} of the OU-1 NAPL when the surfactant concentration was 3%. Column tests using NAPL-coated glass beads showed that the more efficient surfactants could remove >90% of the NAPL after flushing with <10 pore volumes. Brij 97, an ethoxylated alcohol ether surfactant, showed a high capacity for solubilizing the OU-1 NAPL. In a column test using contaminated Hill AFB aquifer material, flushing with a mixture of 3% Brij 97 and 2.5% n-pentanol removed essentially all of the mass of nine target analytes in the NAPL after flushing with <10 pore volumes without mobilizing the NAPL or destabilizing aquifer colloids.

• Research Organization: Univ. of Florida, Gainesville, FL (US)
• OSTI ID: 20012696
• Journal Information: Journal of Environmental Quality, Journal Name: Journal of Environmental Quality Journal Issue: 4 Vol. 28; ISSN JEVQAA; ISSN 0047-2425
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
AQUIFERS
IN-SITU PROCESSING
ORGANIC COMPOUNDS
PERFORMANCE TESTING
REMEDIAL ACTION
SURFACTANTS
VOLATILE MATTER