Mass transfer of organic compounds in dilute aqueous solutions into high density polyethylene geomembranes

Abstract

The mass transfer of ten organic compounds into high density polyethylene (HDPE) geomembranes is investigated using batch immersion tests with dilute aqueous organic compound solutions. For the concentration ranges tested, the linear model is suitable to explain the sorption of organic compounds. The HDPE-water (HDPE-W) partition coefficients of the organic compounds (KHDPE-W) have a good logarithmic linear relationship with their octanol-water partition coefficients and water solubility. The diffusion coefficients (D) of all organic compounds tested are on the order of 10(-9) cm(2)/s and decrease with the increase in their molecular diameters. The effects of the presence of other organic compounds, pH, ionic strength, temperature, and five-year aging of HDPE geomembranes on sorption are evaluated. All factors except the temperature are insignificant. As temperature increase, KHDPE-W values are not affected significantly, but D values increase. A mathematical model, together with the experimentally determined mass transfer parameters, is used to predict the mass flux of organic compounds through HDPE geomembranes.