| 中文题名： | 土壤不同组分对Sb(V)的吸附特征及分配预测模型 |
| 姓名： | |
| 保密级别： | 公开 |
| 论文语种： | 中文 |
| 学科代码： | 083002 |
| 学科专业： | |
| 学生类型： | 硕士 |
| 学位： | 工学硕士 |
| 学位类型： | |
| 学位年度： | 2022 |
| 校区： | |
| 学院： | |
| 第一导师姓名： | |
| 第一导师单位： | |
| 提交日期： | 2022-06-15 |
| 答辩日期： | 2022-06-06 |
| 外文题名： | ADSORPTION CHARACTERISTICS AND DISTRIBUTION PREDICTION MODEL OF ANTIMONY(V) BY DIFFERENT SOIL COMPONENTS |
| 中文关键词： | |
| 外文关键词： | Antimony ; Goethite ; Humicacid ; CD-MUSICmodel ; NOM-CDmodel ; Surfacecomplexationmodel ; RO- ; Soil |
| 中文摘要： |
锑能进行长距离迁移，是一种全球性的环境污染物。土壤矿物组分对Sb(V)的吸附是其在环境中保留的主要机制，而吸附反应会受到土壤理化性质和土壤组分的影响，但目前尚未明确影响其吸附的主要因素和机理。表面络合模型（Surface complexation model，SCM）可以用来探究吸附机理、主控因子和吸附物种的形态分布，为土壤Sb(V)污染的治理提供新思路。所以本文首先通过研究不同环境条件下, Sb(V)在单一土壤组分针铁矿上的吸附特征，并基于扩展X射线吸收精细结构（Extended x-ray absorption fine structure，EXAFS）等光谱学研究结论和宏观实验建立了适用的电荷分配-多点位表面配合模型（charge distribution multisite surface complexation model，CD-MUSIC）。以此为基础进一步探究了胡敏酸对土壤矿物组分针铁矿吸附Sb(V)的影响，并尝试将有机质的影响纳入到预测模型中。最后将天然有机质-电荷分配模型（Natural Organic Matter-Charge Distribution model， NOM-CD）和引入RO-（一种组分）的多表面形态模型（multi-surface speciation model，MSM）扩展应用到Sb(V)在不同类型土壤上的吸附行为预测上，通过批量吸附实验拟合参数，建立较为适用的预测模型，并揭示影响Sb(V)吸附的主控因子和机制，为锑污染防治提供理论和技术支持。主要结论如下：
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（1）单一针铁矿体系： 引入双齿双核和双齿单核络合反应的CD-MUSIC Model Ⅰ更适合预测Sb(V)在针铁矿上的吸附行为。Sb(V)在针铁矿表面更倾向于形成双齿共边和双齿共角络合物。双齿共边络合物是吸附过程中最主要的生成物，受pH的影响比较大；而含量较少的双齿共角络合物对Sb(V)初始浓度依赖性更强。通过改变环境因子（存在Ca2+和PO43-、不同离子强度），模型基本可以实现不同环境条件下针铁矿吸附Sb(V)的预测。高pH时Ca2+通过静电作用增大双齿共角络合物的百分比。而PO43-主要通过竞争表面位点抑制双齿共边络合物，从而促进双齿共角络合物百分比的增大。 （2）胡敏酸-针铁矿体系：随pH的增加，外源添加胡敏酸和GE-HA复合物体系中Sb(V)的吸附量都在逐渐降低，主要是由于静电引力变为静电斥力。针铁矿-胡敏酸复合物对Sb(V)吸附的抑制要远大于外源添加胡敏酸的。复合物体系中，存在团聚现象，造成空间位阻和降低可用吸附位点，抑制作用更强。拟合的NOM-CD模型的参数较适合，在一定范围内能较好地预测胡敏酸对针铁矿吸附Sb(V)的影响。整体上，随pH升高，复合物和外源添加胡敏酸体系中双齿单核络合物的占比始终处于下降，而双齿双核络合物的占比呈上升趋势。但胡敏酸的添加，改变了物种形态比例，由双齿单核络合物是最主要的生成物，转变为双齿双核络合物成为含量较高的生成物。 （3）土壤体系：在吸附平衡状态下，不同的酸碱性土壤的吸附容量存在明显差异，酸性中性土的吸附量明显大于强碱性土。分配系数Kd与pH呈显著负相关，与土壤黏粒含量、非晶型锰铝、游离铁锰铝均呈显著性正相关。进一步建立的经验分配模型，具有较好的模型性能，得到影响Sb(V)在土壤中吸附的主控因子是Mnox，Feox，pH，SOM。 （4）NOM-CD模型和引入RO-的MSM模型整体上合理地描述了不同土壤性质、不同溶液pH值和初始Sb(V)浓度下的实验数据。但高pH时，两个模型都存在拟合结果比实际值偏低的问题。有机质竞争是影响土壤环境中Sb(V)吸附平衡的关键因素，在预测Sb(V)行为时应特别考虑到这一点。RO-浓度与土壤中的非晶型铁含量和DOC含量呈正相关关系。HNOM则主要与吸附在矿物表面的有机质相关。 综上，我们通过递进原则，从研究单一土壤组分对Sb(V)的吸附过渡到土壤上，前者提供了模型参数基础，后者扩展应用，初步探索了较为适用的能预测Sb(V)在土壤上的吸附行为的模型。但建立的机理模型在考虑有机质的影响时都存在一个简化的过程，并且一些组分反应的参数也不确定，所以我们的模型都只是一个较为基础的探究，未来需要更深入的探究以得到最佳的预测模型。 |
| 外文摘要： |
Antimony can migrate over long distances and is a global environmental pollutant. The adsorption of Sb(V) by soil mineral components is the main mechanism for its retention in the environment, and the adsorption reaction will be affected by soil physicochemical properties and soil components, but the main factors and mechanisms affecting its adsorption have not yet been clarified. The surface complexation model (SCM) can be used to study the adsorption mechanism, the main controlling factor and the morphological distribution of adsorbed species, providing new ideas for the treatment of soil Sb(V) pollution. Therefore, this paper firstly studies the adsorption characteristics of Sb(V) on a single soil component goethite under different environmental conditions, and establishes a suitable charge distribution multisite surface complexation model (CD-MUSIC) based on the conclusions of spectroscopic studies such as Extended x-ray absorption fine structure (EXAFS) and macroscopic experiments. Based on this, the influence of humic acid on the adsorption of Sb(V) by goethite is further explored, and the influence of organic matter is tried to be included in the prediction model. Finally, the Natural Organic Matter-Charge Distribution (NOM-CD) model and the multi-surface speciation (MSM) model introduced with RO- (a component) are extended and applied to the prediction of the adsorption behavior of Sb(V) on different types of soil. By fitting parameters of batch adsorption experiment, a more suitable prediction model is established, and the main controlling factors and mechanisms affecting Sb(V) adsorption is revealed. The main conclusions are as follows:
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(1) Single goethite system: The CD-MUSIC Model incorporating bidentate binuclear and bidentate mononuclear complexation reactions is more suitable for predicting the adsorption behavior of Sb(V) on goethite. Sb(V) tends to form bidentate edge- and corner-sharing complexes on the goethite surface. The bidentate edge-sharing complexes are the most important products in the adsorption process, which are greatly affected by pH; while the bidentate corner-sharing complexes with less content have a stronger dependence on the initial concentration of Sb(V). By changing the environmental factors (existence of Ca2+ and PO43-, different ionic strength), the model can basically realize the prediction of Sb(V) adsorption by goethite under different environmental conditions. At high pH, Ca2+ increases the percentage of bidentate corner-sharing complexes through electrostatic interaction. While PO43- inhibits bidentate edge-complexes mainly by competing for surface sites, thereby promoting the increase of the percentage of bidentate corner-complexes. (2) Humic acid-goethite system: With the increase of pH, the adsorption amount of Sb(V) in the exogenous addition of humic acid and GE-HA composite system gradually decreased, mainly due to the change of electrostatic attraction to electrostatic repulsion. The inhibition of Sb(V) adsorption by goethite-humic acid complex is much greater than that of exogenous addition of humic acid. Because in the complex system, there is agglomeration phenomenon, which causes steric hindrance and reduces the available adsorption sites, and the inhibitory effect is stronger. The parameters of the fitted NOM-CD model are more suitable and can predict the effect of humic acid on the adsorption of Sb(V) on goethite within a certain range. On the whole, with the increase of pH, the proportion of bidentate mononuclear complexes in the complex and exogenously added humic acid system always decreased, while the proportion of bidentate binuclear complexes showed an increasing trend. However, the addition of humic acid changed the proportion of species morphology, from the bidentate mononuclear complex is the most important product, into the bidentate binuclear complex. (3) Soil system: In the adsorption equilibrium state, the adsorption capacity of different acid-alkaline soils is obviously different, and the adsorption capacity of acidic and neutral soils is significantly greater than that of strong alkaline soils. The partition coefficient Kd was significantly negatively correlated with pH, and positively correlated with soil clay content, amorphous MnAl and free Fe, MnAl. The empirical distribution model established further has good model performance. The main controlling factors affecting the adsorption of Sb(V) in soil are Mnox, Feox, pH, and SOM. (4) Nom-CD model and RO-introduced MSM model can reasonably describe the experimental data under different soil properties, different solution pH values and initial Sb(V) concentration. However, at high pH, the fitting results of both models are lower than the actual values. Organic matter competition is a key factor affecting the adsorption balance of Sb(V) in the soil environment. This point should be taken into account when predicting Sb(V) behavior, and RO- concentration is positively correlated with the content of amorphous iron and DOC in the soil. HNOM is mainly related to organic matter adsorbed on mineral surface. To sum up, we have transitioned from studying the adsorption of Sb(V) by a single soil component to the soil through the progressive principle. The former provides the basis for model parameters, and the latter extends its application, and preliminarily explores a more suitable method that can predict the adsorption behavior of Sb(V) on soil. However, the established mechanism models have a simplified process when considering the influence of organic matter, and the parameters of some component reactions are also uncertain, so our models are only a relatively basic exploration, and more in-depth exploration is needed in the future to obtain the most best predictive model. |
| 参考文献总数： | 115 |
| 馆藏号： | 硕083002/22010 |
| 开放日期： | 2023-06-15 |
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