Volatilization process of toluene from contaminated soil under consideration of co-existence of pore water

The volatilization process of contaminants has been shown to play an important role in remediation of VOC-contaminated soils. The aim of this paper is to study the volatilization characteristics of both toluene and water from soil, and to evaluate their interaction mechanism under different conditions. A test system is developed to measure mass loss of contaminants and water from soil by volatilization. It was found that basically the volatilization process could be divided into two stages in clay and one stage in sand. Two main influential mechanisms of water on the volatilization of toluene include molecules' competitive adsorption and blocking of volatilization channels. In addition, the evaporation process of water was restricted by volatilization of toluene. Volatilization rate of toluene would increase with the increase of water content when the water content was low. But it would decrease with the increase of water content when the water content was higher than 15% in clay. In addition, there existed an optimal water content (15%) under which the maximum volatilization rate could be achieved.