Diffusion of Volatile Organic Compounds through an HDPE Geomembrane

The diffusion of five volatile organic compounds was quantified in a 2mm thick high density polyethylene (HDPE) geomembrane commonly used in bottom landfill liners in Europe. The VOCs under study were benzene, toluene, dichloromethane (DCM), trichloroethylene (TCE) and 1,2-dichloroethane (DCA) that were mixed together. Glass diffusion cells were especially designed for this purpose. Blank tests were performed to quantify the sorption onto the cell during diffusion testing. Tests were performed in duplicates. The partitioning coefficient of the geomembrane was also determined using batch tests that lasted approximately 100 days. Values of the partition coefficient range between 2 and 101, with the order DCA=DCM<TCE=Benzene<<Toluene. The evolution of concentration with time in the source and receptor chambers of the diffusion cells were interpreted using the numerical code Pollute. Values of diffusion coefficients obtained range between 4.8 x 10^–13 and 1.2 x 10^–12 m²/s with the order benzene<TCE<DCA<DCM. Values of partitioning coefficients and diffusion coefficients are in the range of values obtained in the literature and resulting permeation coefficients are also consistent with data from the literature.