Gas Phase Effective Diffusion Coefficient of Gasoline and Characteristic Components in Dry Fine Sand

Soil vapor extraction (SVE) is an economic and effective in situ remediation technology for contaminated soil. The effective diffusion coefficient of VOCs in porous medium is one of the most important parameters in SVE and directly affects the remediation efficiency and remediation phase classification. Column experiments were conducted with the gas phase diffusion of gasoline and characteristic components which included benzene series and N-alkanes (pentane to dodecane). The gas phase effective diffusion coefficients of the characteristic components were studied. The experiments performed indicate that the components detected are primarily hydrocarbons with fewer carbons in the initial stage of diffusion. The effective diffusion coefficient increases along the distance possibly resulting from the steam partial pressure of gas-phase gasoline. The diffusion of characteristic components is time-ordered and the detected components diffuse steadily with little interaction. The factors of the gas phase effective diffusion coefficient include molecular mass, matter structure, mineral component and water content. The characteristic components fall into four categories and the classification feature is similar to plate theory of gas chromatography.