A Batch-Type Testing Method for Determination of Adsorption of Gaseous Compounds on Partially Saturated Soils
As part of this study, a laboratory batch-type testing method has been developed for determination of the adsorptive characteristics and equilibrium adsorption coefficients for gaseous chemical species on partially saturated soils. The testing procedure was originally developed in support of in-situ tests at radioactive waste disposal sites in which relatively inert tracer gases are injected into the soil as a means of characterizing and monitoring the diffusive migration of gaseous species from a disposal site. The adsorptive capacity of various soils for the tracer gases has been determined at different water contents. Studies show that the testing procedure is practical for the determination of adsorptive capacity of partially saturated soils for volatile organic pollutants. Adsorption coefficients for trichloroethylene (TCE) have also been determined. A wide range of grain-size distribution was investigated. The available adsorption data indicate that soil surface area available for adsorption was of primary importance in the amount of adsorption that occurred for the different soil types. The available surface area for adsorption was decreased by increasing the water content of the soil. The laboratory testing procedure provides a simple and rapid method of assessing the adsorption coefficients, and the results are very reproducible. The testing method can be used to determine the relative adsorptive characteristics of various soil types for essentially any gaseous chemical species whose concentration can be accurately measured.