[Characteristics and influencing factors of trichloroethylene adsorption in different soil types]

Adsorption plays an important role in the transport and the fate of trichloroethylene (TCE) in soil. Six types of soil, including two types of natural soil with different organic carbon content and four types of soil with the low aggregation of "soft carbon" pre-treated by hydrogen peroxide or with all organic carbon removed by high temperature ignition from the original soil, were adopted as adsorbents. The effects of parameters (organic carbon content and composition, minerals, the initial TCE concentration, solution pH, moisture content and ionic strength) on TCE adsorption capacity were examined. The results showed that the soil adsorption isotherm was non-linear within the experimental range. The TCE adsorption capacity was increased and the contribution rate of the minerals to the sorption was reduced with the increase of the organic carbon content. The adsorption of TCE in the soil was the result of the combined action of both organic carbon and minerals, in which organic carbon played a major part, whereas the role of minerals could not be neglected. As the initial TCE concentration increased, the contribution rate of the minerals to the sorption went down. The adsorption isotherm of "soft carbon" was linear, while the "hard carbon" was non-linear. Moreover, the adsorption capacity was increased by increasing the ionic strength. In contrast, neither pH nor moisture content had any influence on TCE adsorption.