F. Dierkes et al., LOW-TEMPERATURE MICROEMULSIONS FOR THE IN-SITU EXTRACTION OF CONTAMINANTS FROM SOIL, Colloids and surfaces. A, Physicochemical and engineering aspects, 141(2), 1998, pp. 217-225
A complex microemulsion system using rape oil-methyl ester as the oil
component, anionic and non-ionic surfactants and brine was developed f
or the in situ extraction of hydrophobic contaminants at temperatures
of about 10 degrees C. The phase behaviour at different compositions o
f quaternary, quinary and hexanary systems was studied. The behaviour
was governed by the anionic surfactant. The concentration of brine str
ongly influences the phase behaviour. In addition, increasing the salt
concentration leads to the suppression of liquid crystals. The additi
on of a third, very bulky surfactant further suppresses the formation
of liquid crystals for equal mass fractions of oil and brine. Equal am
ounts of oil and water are necessary to avoid the formation of liquid
crystals. A system with low surfactant concentration was chosen to det
ermine the viscosity and surface tension. First column experiments wer
e performed in order to determine the flow behaviour and the amounts o
f microemulsion components adsorbed onto soil. In a batch experiment,
the extraction efficiency of the microemulsion system was investigated
at 10 degrees C for polychlorinated biphenyls from a doped soil. It w
as better than the efficiency of the toluene extraction. Microemulsion
systems seem to be excellent media for the in situ remediation of hyd
rophobic contaminants from soil. (C) 1998 Elsevier Science B.V. All ri
ghts reserved.