Investigation of the effect of moisture on the sorption and desorption of chlorobenzene and toluene from soil

Abstract

The sorption isotherms of chlorobenzene and toluene on a standard EPA soil at different relative humidities were measured using a dynamic technique based on frontal analysis chromatography. At 0% relative humidity, the isotherms were BET (Brunauer-Emmett-Teller) type II isotherms, indicating monolayer coverage of the surface followed by multilayer coverage. As the relative humidity increased, the shape of the isotherm became progressively a type III isotherm, indicating weaker adsorbent/adsorbate interactions. The presence of water greatly reduced the organic uptake by soil, especially at low organic concentrations. The effect of humidity was attributed to adsorptive displacement of the organic by water. A mechanistic approach was considered to evaluate the contribution of the possible sorption mechanisms to the total sorption