VOC removal from water and surfactant solutions by pervaporation: a pilot study

The removal of VOCs from aqueous solutions via pervaporation is an establis hed technology that has been successfully demonstrated at the full scale. T he purpose of this research was to measure the effect of an anionic surfact ant (DOWFAX 8390) on pervaporation system performance and mass transfer of 1.1.1 trichloroethane (TCA) and toluene. This aqueous surfactant applicatio n of pervaporation targets the recovery and reuse of surfactant from SEAR ( surfactant enhanced aquifer remediation) process fluids. In this Study. a p ilot scale pervaporation unit with 4 spiral wound modules was used to condu ct 75 eight hour runs. Process variables included temperature (30, 40. 50, 60 degreesC), permeate pressure (15, 25. 55 Torr), flow rate (0.25-2.0 gpm) . and VOC feed concentration (17-265 mg/l TCA and 5-200 mg/l toluene). Surf actant addition reduced the removal of VOCs 0.7-29% depending on the system flowrate, feed temperature, and VOC. The reduced VOC flux resulting from t he addition of surfactant was found to be attributed to an increase in the liquid viscosity due to the addition of the surfactant (10-13%, increase) a nd partitioning of the VOC into the surfactant micellar phase (63-68%, of T CA and 73-78%, of toluene was in micellar form) under experimental conditio ns. Though the addition of surfactant causes a decrease in the VOC removal efficiency, this study demonstrates that pervaporation can be used to remov e VOCs from surfactant solutions without affecting the surfactant. permitti ng surfactant recycle. (C) 2001 Elsevier Science B.V. All rights reserved.