【作者】 马月姣；

【导师】 毕二平；

【作者基本信息】 中国地质大学(北京) ， 地下水科学与工程， 2012， 硕士

【摘要】 汽油类污染物对土壤和地下水的污染日益严重。土壤作为污染物的主要污染场所，研究其不同组成介质对污染物的吸附以及污染物在其介质中的运移规律有着重要意义。本文选取典型汽油组分苯、甲苯和甲基叔丁基醚( Methyl tert-butyl ether，MTBE )作为目标污染物，利用室内静态吸附批实验和动态土柱实验，模拟它们在典型饱水孔隙介质中的吸附和运移过程，研究得到如下结论：(1)选取某采油厂不同有机碳含量的表层土壤作为吸附剂，用批实验方法对苯和甲苯的单组分吸附和双组分竞争吸附行为进行研究。结果表明：单组分溶液中，苯和甲苯在土壤中的吸附符合线性规律，吸附能力与土壤有机碳含量成正比；双组分溶液中，苯和甲苯存在竞争吸附，土壤对它们的吸附能力小于单组分时的情况，竞争吸附的结果表明，介质表面点位对苯和甲苯的吸附也起着重要的作用。(2)选取高岭土和磁河土壤为吸附剂，用柱实验方法对MTBE、苯和甲苯的吸附运移过程进行研究。结果表明：高岭土中，MTBE穿透曲线呈现对称现象，表面吸附为主要吸附机理。磁河土壤中，由于土壤有机质的存在，MTBE会与其发生化学吸附作用，穿透过程表现解吸阶段缓慢下降，表面吸附和分配作用共存。(3)典型汽油组分到达穿透曲线峰值的时间顺序依次为：MTBE、苯、甲苯，即不同饱水孔隙介质对甲苯的吸附能力最强，甲苯的竞争吸附能力最强。由于分子量大、溶解度低，苯和甲苯在孔隙介质中的解吸滞后现象较明显。(4)模拟土壤溶液CaCl2浓度的增大时，提高了颗粒之间相互碰撞吸附几率，吸附点位增多，吸附能力增大，使得有机污染物的洗脱流出液相对浓度降低。而磁河土壤中，CaCl2浓度的升高时，由于有机质易于与Ca2+形成络合物，阻碍污染物与土壤介质接触，使有机物苯和甲苯的迁移速率加快，洗脱流出液相对浓度增大。(5)非线性Freundlich模型在平衡和非平衡状态下均能对典型汽油组分在饱和孔隙介质中的运移进行较好的模拟。两点非平衡模型( TSM )对典型汽油组分在磁河土壤中的运移模拟效果较好，而高岭土中则相对较差。因此，汽油类污染物在不同饱水孔隙介质中的吸附运移过程主要受到非线性吸附的影响。随着孔隙介质土壤有机质百分含量的增加，污染物的运移过程也受到化学非平衡吸附的影响。更多还原

【Abstract】 Gasoline contaminants have caused serious pollution problems in soil andgroundwater. It is of significance to study the sorption and migration of oragnicpollutants in different components of the soil, because soil is a main sink of pollutants.Inthis thesis, benzene, toluene and methyl tert-butyl ether ( MTBE ) were selected as thetarget pollutants. Batch experiments and column experiments were used to study theadsorption and transport of organic pollutants in typical saturated porous media.Conclusions were summarized as follows:(1) Batch experiments were carried out to investigate the sorption and competitivesorption between benzene and toluene to soils of different organic carbon content.Single-solute solution experiments showed that sorption of single compound to soils canbe described by a linear sorption isotherm, and the sorption capacity is proportional tosoil organic carbon content. In bi-solute solution experiments, competitive sorption ofsolutes was observed and caused a decrease of sorption capacity of target compoundwhen compared to that of single-solute cases. The competitive sorption results indicatedthat sorption of organic compounds to specific sites on the solid surface probably playedan important role.(2) Column experiments were carried out to investigate the sorption and migrationin kaoline and Cihe soil columns. The breakthrough curves ( BTCs ) of MTBE showedthe symmetrical phenomenon. But in Cihe soil, the BTCs of MTBE slowly declined indesorption stage, with a long tail in the desorption stage, so the mainly adsorptionmechanism is chemical adsorption, because there are soil organic carbons in soil.(3) The order of typical gasoline components reaching the peak time of BTCs isMTBE, benzene and toluene. Due to the large molecular weight and low solubility ofbenzene and toluene, the desorption hysteresis of benzene and toluene in porous media ismore obvious. (4) With the increase of the concentration of CaCl2, kaoline crystals within the filmlayer spacing increases, adsorption point increase, the adsorption capacity increases. InCihe soil, complexation organic matter with Ca2+, hinders pollutants contacting withCihe soil. Therefore, the leaching rate of benzene and toluene became faster, and theleaching concentration increased if the CaCl2concentration increased in the solution.(5) The transport of typical gasoline components in saturated porous media can bewell simulated by the Freundlich model. The transport of typical gasoline components inCihe soil can be better simulated by the two-site model with CXTFIT than in kaoline.Therefore, the adsorption of the organic pollutants in the saturated porous mediumtransport processes was affected by nonlinear adsorption. With the soil organic carboncontent increases, the organic pollutants were also affected by chemical non-equilibriumadsorption.更多还原