Surfactant-enhanced regeneration of gas phase application ganular activated carbon and XAD-4 polymeric resin

Abstract

This research work presents the regeneration of trichloroethylene (TCE)-saturated adsorbents (granular activated carbon (GAC) and polymeric resin) with a surfactant, sodium dodecyl sulfate (SDS), in an aqueous solution in a column contactor. The effects of bed height and various parameters (i.e. water flushing, flow rate of regenerant solution, concentration of SDS in regenerant solution, flow rate of water during flushing step) on the effectiveness of regeneration were investigated. Results indicated that the minimum bed height of GAC providing a full length of breakthrough curves for both fresh and regenerated GAC was 3.6 cm corresponding to 9 g of GAC. More than 95% of TCE was desorbed from both adsorbents. However, only 15% and 60% of fresh GAC and fresh polymeric resin adsorption capacity could be recovered. For the investigation of parameters influencing effectiveness of regeneration, the water flushing can improve their adsorption capacity by the factor of two. The regenerant solution flow rate and concentration of SDS in regenerant solution did not affect the removal of TCE for GAC whereas they affected the polymeric resin. Therefore, the removal of TCE is limited by mass transfer for GAC while it is limited by equilibrium for the resin. The water flow rate during the flushing did not affect the removal of SDS. Results from the thermal gravimetric analysis (TGA) confirmed that TCE and SDS residual remain on both adsorbents surface.