DESORPTION OF TRICHLOROETHYLENE IN AQUIFER MATERIAL - RATE LIMITATION AT THE GRAIN SCALE

Soil-gas venting for the removal of sorbed trichloroethylene (TCE) was studied in columns packed with either wet or oven-dry Santa Clara aquifer material. After the wet columns were vented up to 1 h, the removal rate was independent of the flow rate and limited by slow intra-particle mass transfer. In contrast, removal of TCE from columns filled with oven-dry material was proportional to the flow rate after 20 days of venting. This suggests that intraparticle pore water limits mass transfer from the internal sorption sites. Desorption was modeled using an intraparticle diffusion model assuming homogeneous porous spheres. The model was calibrated in batch sorption studies using the apparent diffusion rate constant as a fitting parameter.