Volatile organic compounds emission from contaminated soil during surfactant washing

The emission characteristics of aromatic and aliphatic volatile organic compounds (VOCs) produced by two kinds of surfactants, nonionic Triton X-100 (TX-100) and cationic domiphen bromide (DB), washing high and low soil organic matter (SOM) soils were evaluated with two mass-balance equations. The influential factors on volatilization mass were primarily related to the affinity of the VOCs to the soils and to the surfactant solutions. The results show that the VOC emissions are a function of Koc, the surfactant properties and the S-w and P of the VOC. Nonionic surfactants could more effectively wash the VOCs away from the soil, leading to relatively higher emissions. When the surfactant concentrations exceeded the critical micelle concentrations (CMCs), VOC partitioning into the surfactant sorbed on the soil surface to reduce the VOC emissions. Whether the VOC can freely dissolve in the solution is the key point in determining the volatilization parameters. The emission of dissolved VOC is dependent on K-OL and S-w. The P is the major parameter governing the emission of VOCs in an insoluble state. The solution properties can strongly affect the emissions of low S-w compounds due to solubility enhancement effects. The main effects on higher S-w compound emissions were the amounts of the surfactants adsorbing on the soil surface.