Simultaneous removal of chlorinated contaminants by pervaporation for the reuse of surfactant

Abstract

Surfactants are widely used for the remediation of groundwater contaminated with chlorinated solvents. The reuse of surfactants is quite important for the economic feasibility of the remediation process. Pervaporation with a polydimethylsiloxane membrane was conducted to simultaneously separate trichloroethylene (TCE) and tetrachloroethylene (PCE) from waste solution of the non-ionic surfactant Tween 80. The effects of key process variables on the removal efficiency were investigated. Membrane thickness between 200 pm and 300 mu m did not affect the pervaporation performance. Organic flux did not increase above the flow rate of 100 mL/min. The increase of feed concentration and temperature led to large organic flux. Selectivity was reduced significantly with temperature due to the increase in thermal motion of polymer. The reduction of flux was small below 1.0 wt% surfactant (Tween 80) in feed solution. Flux and selectivity of TCE were higher than those of PCE because an extramicellar portion of TCE was higher than that of PCE. In simultaneous pervaporation of TCE and PCE, flux and selectivity declined due to the competitive sorption of TCE and PCE. However, the reduction percentage in flux and selectivity was less than 10% with 1:1 ratio of TCE/PCE. With operation during 100 h, over 95% of TCE and 90% of PCE were simultaneously removed from 0.5 wt% of Tween 80 solution with TCE and PCE of 1,000 ppm. From the present results, which gave a high efficiency in the simultaneous removal of chlorinated solvents, this process could be a practical alternative for surfactant reuse.