【作者】 张海龙；

【导师】 李梦耀；

【作者基本信息】 长安大学 ， 应用化学， 2014， 硕士

【摘要】 Mn2+（阳离子）﹑Cr(Ⅵ)（阴离子）和2,4-二氯苯酚（分子）是存在形式不同的环境污染物，具有生物毒性高，残留时间长、挥发性低，无降解或难降解等特性。宁夏中宁县地处黄土高原带，是我国重要的锰生产基地，分布着众多铬加工企业，化工企业排放的污水中有2,4-二氯苯酚存在。研究Mn2+﹑Cr(Ⅵ)和2,4-二氯苯酚等三种污染物在黄土性土壤中的吸附、运移、转化规律，对理解不同污染物在黄土性土壤中的物理化学行为和归宿，对预测它们在宁夏中宁黄土地区对土壤及地下水潜在污染有着重要的理论及现实意义。本文在中宁不同地点采集理化性质差异较大的两个黄土为黄土性土壤样品，测定了其矿物组成和重要的理化性质，采用静态与动态实验相结合的方法，研究了黄土性土壤吸附Mn2+﹑Cr(Ⅵ)和2,4-二氯苯酚的动力学与热力学规律，测试了吸附过程焓、熵、吉布斯自由能等重要热力学状态函数的变化，确定了吸附模型；采用淋渗实验和一维土柱实验分别研究了Mn2+﹑Cr(Ⅵ)和2,4-二氯苯酚在黄土性土壤中的迁移转化规律，建立了Mn2+在饱水介质中的一维迁移转化数学模型，实验测定了模型参数，将Mn2+在黄土性土壤中的时空分布值与模型计算值对比，验证了模型的可靠性。论文取得的重要研究结论如下。1.黄土性土壤对存在形式不同的Mn2+﹑Cr(Ⅵ)和2,4-二氯苯酚等三种污染物的吸附存在着较大差异。①黄土类土壤对三种污染物的吸附能力为：Mn2+＞2,4-二氯苯酚＞Cr(Ⅵ)，对于同一污染物的吸附能力：TM-1＞TS-2；根据Laμgmuir方程计算出TM-1和TS-2D对Mn2+的平均最大吸附量分别为：1250mg/kg和714mg/kg；②Mn2+、2,4-二氯苯酚在两种土壤中的吸附自由能△G0均为负数，这说明吸附过程可以自发进行；焓变△H0也都为负数，表明两种土壤中Mn2+、2,4-二氯苯酚吸附都为放热反应；两种土壤吸附2,4-二氯苯酚的△S则皆为负值，表明其吸附使微观分子趋于有序排列；土壤对Mn2+吸附时△S为正值，表明比反应体系中混乱度增加。2. Mn2+﹑Cr(Ⅵ)和2,4-二氯苯酚等三种污染物在黄土性土壤中的迁移速率不同。Mn2+、2,4-二氯苯酚和Cr(Ⅵ)在黄土中的吸附和迁移与土壤本身有关，同一污染物在TS-2中迁移速度大于TM-1；对于同一土壤迁移速度为：Mn2+＜2,4-二氯苯酚＜Cr(Ⅵ)，土壤对Mn2+的净化能力远大于2,4-二氯苯酚和Cr(Ⅵ)。3. Mn2+在黄土性土壤中的迁移转化受到了水动力弥散、吸附与解吸的共同作用，Mn2+在较高浓度下（200mg/L）的吸附遵从亨利线性模型q=Kdc，实验测得其在TM-1土样吸附系数K=5.15cm3/g；迟滞因子R=25.75；弥散系数D=0.00618m2/d；平均流速V=2.08m1/min； TS-2吸附系数Kd2=2.41cm3/g、迟滞因子R2=18.64、弥散系数D2=0.00368m2/d、平均流速V2=2.3ml/min；建立了Mn2+在地上水中时空分布的数学模型，并将模拟值与实验实测值进行对比，发现二者重合性较好，表明该水动力弥散模型可很好的模拟和预测Mn2+在地下水多孔介质中的时空分布。更多还原

【Abstract】 Mn2+(cation)﹑Cr (Ⅵ)(anion) and2,4-dichlorophenol (numerator) are environmentalpollutants with existence of different forms. They have a high toxicity, long residual time, lowvolatility, and other non-degradable or biodegradable characteristics. Zhongwei region islocated in the Loess Plateau. Loess soil is an important venue in the area of agriculture,industry, forestry, animal husbandry and urban construction, the area is an importantproduction base of manganese,and there are many processing enterprises of chromium and2,4–dichlorophenol here.Study of the adsorption, transport, transformation rules of Mn2+﹑Cr(Ⅵ) and2,4-dichlorophenol in Loess soil, can provide important theoretical and practicalvalue for predicting their potential contamination in Zhongning loess soil and groundwater.We selected two differences soils(TM-1and TS-2) from Zhongwei for the study, Analyzed thecomposition and basic physical and chemical properties of the two soils. Studied the kineticsand thermodynamics laws of the loess soil adsorpiting the Mn2+﹑Cr (Ⅵ) and2,4-dichlorophenol. Tested the adsorption enthalpy change process, entropy, Gibbs freeenergy and other important thermodynamic state function and determined the adsorptionmodels. Throμgh the one-dimensional diffusion test, established a mathematical model ofMn2+transport and transformation in saturated loess soil, Determining the modelparameters.Moreober, the results determined form those modes has a well coherence with theexperiments,which indicated that the diffusion modes can be used to simulate of Mn2+in theloess soil well. Specific results are as follows:1.There is a big difference of the loess siol adsorpiting the Mn2+﹑Cr (Ⅵ) and2,4-dichlorophenol.①The adsorption capatiy of the loess soil is Mn2+>2,4–dichlorophenol> Cr (Ⅵ). Forthe same pollutants,the adsorption capacity is TM-1>TS-2. Calculated by Langmuir equationthe average absorption quantity of lossial soil to Mn2+is1250mg/kg to TM-1and714mg/kgto TS-2.②Both△G0and△H0are negative, so the adsorption of2,4-dichlorophenol and Mn2+inloess belongs to an exthernal spontaneous rection.and it also says the adsorption can beautomatically.△S of the2,4-dichlorophenol is negative, indicating that the adsorbed molecules tend to make micro-ordered; earth△S of the Mn2+is positive, indicating anincrease of the degree of disorder in the reaction system.2.The migration rate of Mn2+﹑Cr (Ⅵ) and2,4-dichlorophenol in the loess soil isdifferent. The migration of Mn2+,Cr (Ⅵ) and2,4–dichlorophenol in loessial soil relate toThe soil itself. The order of migration are TS-2>TM-1, Mn2+<2,4–dichlorophenol<Cr (Ⅵ).The soil purification capacity to Mn2+is much greater than2,4-dichlorophenol and Cr (Ⅵ).3.The Mn2+vertical migration in loess soil by the hydrodynamic dispersion, adsorptioninteraction.For the TM-1, the adsorption coefficient Kdl=5.15cm3/g, retardation factor R1=25.75,diffusion coefficient D1=0.00618m2/d, the average velocity V1=2.08m1/min; adsorptioncoefficient Kd2=2.41cm3/g, retardation factor R2=18.64, diffusion coefficient D2=0.00368m2/d, the average velocity V2=2.3ml/min. The establishment of a mathematicalmodel of Mn2+ground water distribution in space and time, and the simulated andexperimental measured values are compared and found that both coincide better, indicatingthat the hydrodynamic dispersion model can simulate and predict good Mn2+in groundwaterin porous media the spatial and temporal distribution.更多还原