Comparison of batch and double compartment tests for measuring voc transport parameters in geomembranes

Abstract

Partition and diffusion coefficients for volatile organic compounds (VOCs) and geomembranes obtained using batch and double compartment (DC) tests are compared. Tests were conducted with a high-density polyethylene (HDPE) geomembrane and solutions containing five common VOCs ranging in hydrophobicity. Batch tests were conducted in equilibrium and kinetic modes using solutions with single or multiple solutes. The findings indicate that competitive sorption between solutes is negligible for the concentrations examined, except for the most hydrophobic compounds, and that partition coefficients obtained from equilibrium and kinetic batch tests cannot be distinguished statistically. DC tests yield larger partition coefficients, and smaller diffusion coefficients, due to losses in the DC apparatus. Kinetic batch tests are recommended to simultaneously obtain partition and diffusion coefficients for VOCs and geomembranes. The kinetic batch test method is relatively simple and expedient, the partition and diffusion coefficients are reliable, and the data can be analyzed using an analytical solution programmed in a spreadsheet application. Empirical relationships are recommended to estimate the partition coefficient, diffusion coefficient, and permeation coefficient for VOCs and HDPE geomembranes using common chemical properties.