Estimation of diffusion coefficients and solubilities for organic solvents permeation through high-density polyethylene geomembrane

Experiments on the permeation of several chlorinated and aromatic hydrocarbons through high-density polyethylene (HDPE) geomembranes were conducted using the ASTM F-739 standard test method. The diffusion coefficients were estimated by a one-dimensional diffusion equation based on Fick's second law, and the solubilities of the solvents in HDPE were determined by the steady state permeation rates. The one-dimensional transient model was able to simulate the permeation concentrations and implied that equilibrium partition between organic solvent and HDPE geomembrane was not achieved during the initial permeation. The solubilities of organic solvents in the HDPE geomembranes obtained by immersion tests or weight gain methods of permeation experiments were not an appropriate boundary condition for the model simulation of permeation. It was found that the diffusion coefficients and solubilities of organic solvents correlated well with their molecular weights and dipole moment, respectively. The present work provides information on the extent of organic compounds permeations through HDPE geomembranes as applied in hazardous waste landfills.