Surfactant recovery by liquid-liquid extraction and reverse micellar extraction

Abstract

This study aimed to investigate two extraction techniques namely liquid-liquid extraction (LLE) and reverse micellar extraction coupled with ultrafiltration process for tetrachloroethylene (PCE) removal and surfactant recovery purposes. Using surfactant solution to remediate NAPLs gains more attractions. Nevertheless, prior reusing surfactant, a decontamination of surfactant solutions is recommended. In this study, we imitated the surfactant solution similar to one pumped out of the contaminated site, which contains 4%AMA (anionic surfactant), 3%NaCl and 10,000 ppm solubilized PCE. The conventional LLE using five extracting solvents varying the equivalent alkane carbon number (EACN) was investigated to determine the partitioning of PCE from surfactant solution into solvent phase and the %PCE removal. The reverse micellar extraction is another extraction technique based on Winsor type II microemulsion formation, where the micelles break up, migrate into the solvent phase and re-aggregate to form reverse micelles. The released PCE during the micelles break up also partitions into the solvent phase. The result showed that the EACN of extracting solvent and the surfactant solution:solvent volumetric ratio were crucial parameters governing the extraction efficiency of LLE. In addition, other parameters such as molecular structure and functional groups of solvent also have an influence on the PCE partitioning and PCE removal in LLE technique. For reverse micellar extraction, the surfactant solution:solvent volumetric ratio (ranged from 40:1 to 5:1) used in this study did not show significant effects on the surfactant removal (84.9-86.9%) and PCE removal (96.7-98.4%). Furthermore, an ultrafiltration process was used as an additional downstream process after reverse micellar extraction to concentrate the surfactant