Diffusive Transport of Phenolic Compounds Through Two Coextruded Geomembranes

This paper presents experimental results of a study of the diffusion of phenolic compounds through two High density polyethylene geomembranes (1 and 1.5 mm thick) with a coextruded ethylene vinyl-alcohol (EVOH) inner core. The partition and diffusion coefficients were quantified for 2,4,6-tricholophenol (2,4,6-TCP), 2,3,5,6-tetrachlorophenol (2,3,5,6 TeCP), and pentachlorophenol, which are known to be toxic even at very low concentrations. The concentration dynamics in the source and receptor chambers of the diffusion cells was interpreted with the help of the numerical code POLLUTE. For partition coefficients greater than those obtained under the same conditions for a high-density polyethylene (HDPE) geomembrane, the diffusion coefficients are smaller than those for the same HDPE geomembrane. As a result, the permeation coefficient of the two coextruded geomembranes is the same order of magnitude as that of a 2-mm-thick HDPE geomembrane. Therefore, in contrast to the case for volatile organic compounds, the EVOH inner core brings no significant improvement. These results are compared to those previously obtained with volatile organic compounds for HDPE geomembranes and coextruded geomembranes.