The effects of system variables on soil-vapor extraction of benzene and p-xylene in an unsaturated desert soil
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PublisherThe University of Arizona.
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AbstractWater-unsaturated column experiments using benzene and p-xylene were performed with a desert soil sample (fc = 0.001) to simulate the removal of volatile organic compounds (VOC) by soil-vapor extraction. Higher flow rates of air were found to facilitate quicker VOC removal but lower flow rates were more efficient. Initial concentrations had no effect on the rate of VOC removal. Sorption of both compounds by the solid phase at 18 and 10 percent wetness was similar to that reported for saturated systems. At these moisture contents, Kp the for benzene averaged 0.03 cm 3/g and that for p-xylene averaged 0.61 cm 3/g. At the driest soil condition, higher than predicted sorption of benzene (Kp = 0.12 cm3/g) is attributed to VOC sorption on dry mineral sites. Mechanisms that limited transport of both compounds are assumed to be intra-aggregate aqueous diffusion and desorption. (Abstract shortened with permission of author.)