Un. Choori et al., REMOVAL OF VOLATILE ORGANIC-COMPOUNDS HORN SURFACTANT SOLUTIONS BY FLASH VACUUM STRIPPING IN A PACKED-COLUMN, Ground water monitoring & remediation, 18(4), 1998, pp. 157-165
Volatile organic compounds (VOCs) can be removed from contaminated gro
und water and subsurface media by surfactant-enhanced remediation proc
esses. For the process to be economically competitive it is necessary
to recover and reuse the surfactant from this concentrated solution. T
he VOC can be removed from this concentrated solution by flash vacuum
stripping, leaving the surfactant solution for reuse. In this study, t
he flash vacuum stripping of trichloroethylene (TCE) from an anionic s
urfactant solution in a co-current packed column was studied under rou
gh vacuum conditions. The presence of surfactants lead to a reduction
in the overall liquid phase volumetric mass transfer coefficient (MTC)
of 40 to 95%, depending on flow rate and surfactant concentration at
50 degrees C and 16 kPa. At liquid loading rates of less than 13 cm(3)
/cm(2)min, the MTC of TCE decreases rapidly with an increase in liquid
loading rate, and at liquid loading rates above that, the MTC decreas
es slightly with an increase in the liquid loading rate. This trend ma
y have been due to foaming. At surfactant concentrations above the cri
tical micelle concentration, the effect of surfactant concentration wa
s not significant at liquid loading rates less than 13 cm(3)/cm(2)min.
However, beyond that rate, the MTC of TCE decreased drastically with
an increase in surfactant concentration. The MTC of TCE increased with
an increase in temperature. A large pressure drop (3 to 4 kPa/m) was
observed across the packed bed due to foaming.