A comparative assessment of volatile organic compound (VOC) sorption to various types of potential GCL bentonites

Abstract

The potential improvement in the sorption of volatile organic compounds (VOCs) to bentonite used in Geosynthetic Clay Liners (GCLs) is examined for mixtures of bentonite and several organoclays or activated carbon. Results of batch tests performed with dichloromethane (DCM), 1,2-dichloroethane (1,2-DCA), trichloroethylene (TCE), benzene and toluene are reported. It is shown that all organoclays could potentially increase VOC sorption to GCLs by several orders of magnitude but activated carbon generally appears to provide the most improvement for the samples tested. The engineering relevance of this potential improvement is assessed with respect to design of municipal solid waste landfill liner systems by performing contaminant transport modeling. It is shown that only slight changes in contaminant migration will occur, despite the large potential increases in GCL sorption. This suggests that increased costs associated with modifying GCLs may outweigh the benefit of such additives to GCLs for municipal solid waste landfill applications for the conditions examined herein.