Diffusion Coefficients of Organics in High Density Polyethylene (HDPE)

Abstract

Only limited data are available on the diffusion of volatile organic solvents through flexible membrane liners (FMLS) used for lining impoundments and landfills. To expand this database, a rapid, inexpensive method is needed to measure the diffusion coefficients of volatile organic solvents through FML materials. An absorption method has been developed to determine the diffusion coefficients of volatile organic solvents through FML materials. The method is based on the depletion of an organic compound from an aqueous solution due to absorption by a submerged sample of FML. A numerical solution of Fick's second law of diffusion was used to develop a graph which can be used to determine the diffusion coefficient from the time dependent concentration data. The diffusion coefficients obtained from the absorption tests were validated by comparing them with coefficients determined using a two chamber diffusion cell. The diffusion coefficients determined for toluene and xylene in high density polyethylene (HDPE) were 5.1 × 10-9 cm2s-1 and 1.0 x 10-9 cm2s-1 by the two methods, respectively. The data indicate that the coefficient of distribution (Kd) between the FML and the organic solution, a value which is needed to calculate the diffusion coefficient from the data, can be estimated from the log of the octanol-water partition coefficient (Kow), a commonly measured and reported value for many chemicals.

Geomembrane applications for controlling diffusive migration of petroleum hydrocarbons in cold region environments

“…Diffusion of a vapour or aqueous organic compound through a geomembrane occurs over three steps: adsorption, diffusion and desorption (Park and Nibras, 1993;Prasad et al, 1994;Sangam and Rowe, 2001;Pierson and Barroso, 2002;Stark and Choi, 2005) and the overall process is referred to as permeation. During adsorption, the contaminant partitions between the source medium (whether liquid or vapour) and the adjacent surface of the geomembrane.…”

A review of the performance of geosynthetics for environmental protection

“…A number of studies on the use of GMs have focused on the diffusion of VOCs through virgin HDPE GMs (Park and Nibras, 1993;Prasad et al, 1994;Müller et al, 1998;Sangam and Rowe, 2001;Park et al, 2012) virgin PVC, linear lowdensity polyethylene (LLDPE) GMs with and without a coextruded ethylene vinyl-alcohol (EVOH) inner core (McWatters andRowe, 2008, 2010;Eun et al, 2014), fluorinated HDPE GMs (Sangam and Rowe, 2005), and aged HDPE GMs (Rowe et al, 2003;Islam and Rowe, 2009). The diffusion coefficients of VOCs in virgin HDPE GMs are 0.37 Â 10 À13 and 22.8 Â 10 À13 m 2 /s for benzene and DCM, respectively, with partition coefficients ranging from 1.8 to 189.…”

Diffusion and solubility coefficients determined by permeation and immersion experiments for organic solvents in HDPE geomembrane

“…The immersion method is a simple and expedient gravimetric test [6,11]. In contrast to the ASTM F739 method, both surfaces of geomembrane sample are in contact with the tested chemical for immersion method.…”

“…Many industrial wastes, such as organic solvents, are currently dumped into landfills, especially for developing countries. Even though, polymeric geomembranes are non-porous materials and are impermeable to liquids, the waste chemicals or landfill leachate may still permeate through geomembranes by diffusion [1][2][3][4][5][6].…”