| Sorption of organic pollutants by soilsk/sediments plays an important role in their transport, fate and bioavailability in natural environment. In response to the serious pollution of soils and groundwater, it is interested to understand and evaluate the sorption behaviors of organic pollutants on soils/sediments, and to control the sorption behaviors. Surfactants, in natural environment, effect the sorption behaviors of organic pollutants onto soils/sediments, which offers a potential way to protect soils/ground-water or to remediate the polluted soils/groundwater. In this dissertation, the sorption behaviors and mechanisms of organic pollutants and surfactants onto soils/sediments were investigated; the control methods on the sorption of surfactants and even organic pollutants onto soils/sediments by mixed surfactants were disscussed detailedly. The main original conclusions of this dissertation are:(1) It is observed that soil/sediment organic matter is response to the sorption nonlinearity of nonpolar or polar organic pollutants on soils/sediments. Partition coefficients and adsorption coefficients for organic pollutants are both linear with the soil/sediment organic carbon content, rather than the clay content and the surface area. The partition coefficients and adsorption coefficients normalized by organic carbon content are relatively constant, and linear with the solubilities of organic pollutants by a negative way. Then, a model was developed to calculate the nonlinear sorption of organic pollutants on soils/sediments by tow parameters (the soil/sediment organic carbon content and the water solubility of organic pollutants) only.(2) The importance of soil/sediment organic matters and clay minerals on their sorption of Triton X-100 was investigated by the multi-component statistic analysis. It is indicated that sorption of Triton X-100 on soils or sediments is the combined contribution of soil/sediment organic matters and clay minerals, which depended on both the contents of soil/sediment organic matters and the types and contents of clay minerals. The sorption power of soil/sediment composition for Triton X-100 conforms to an order of montmorillonite > organic carbon > illite >1.4nm minerals (vermiculite + chlorite + 1.4 nm intergrade mineral)?kaolinite.(3) Losses of anionic surfactant on soils/sediments is attribute to the precipitation between anionic surfactanta ions and soil/sediment divalent cations. The cation exchange between soil/sediment and Na+ leading to the release of Ca2+ and subsequent precipitation of anionic surfactants (SDBS) in solutions, are the mechanisms of precipitation. Precipitation exists in solution but not happens in the interlayer of clay such as montmorillonite.(4) Desorption of phenanthrene from soil to water are more efficiency by mixed Triton X-100 and SDBS solutions than by the individual surfactants. For example, theminimizing losses of surfactants at the mass ratio 1:9 of Triton X-100 and SDBS, the highest desorption efficiency of phenanthrene from soil is observed. The enhanced desorption by mixed anionic-nonionic surfactants is primarily due to the minimizing losses of surfactants. Mixed micelle formation, which inhibits the adsorption of Triton X-100 on soil and the precipitation of SDBS with Ca2+, is responsible for the minimizing losses of Triton X-100 and SDBS in their mixed systems. A model is suggested to calculate the critical washing concentrations from the losses and the critical micelle concentrations of surfactants.(5) The sorption of organic pollutants onto soils/sediments is enhanced by the co-existed nonionic or cationic surfactant, and will be significantly enhanced by their mixtures. The sorption capability of sediment for nitrobenzene is enhanced 50, 9.1 and 70 times by CPC, Triton X-100 and their mixtures, respectively. The organic matter content enhanced by the cosorption of nonionic and cationic surfactant, is response to the enhanced sorption capability of soil/sediment.
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