Knowledge Resource Center for Ecological Environment in Arid Area
| 高分子在重金属污染土壤修复和保水治沙方面的应用 | |
| 其他题名 | Application of polymer in the remediation of heavy metal contaminated soil and water conservation on sandy soil |
| 尹铮 | |
| 出版年 | 2016 |
| 学位类型 | 博士 |
| 学位授予单位 | 中国科学院大学 |
| 中文摘要 | 随着我国工业化和城市化的飞速发展，我国所面临的土壤问题也日益严峻。其中土壤重金属污染和土壤荒漠化是两类非常严重的土壤问题，已引起人们的密切关注。原位钝化法和保水剂添加法分别是治理重金属污染土壤和土壤荒漠化的常用方法，但是传统的钝化修复剂和保水剂通常存在成本高，难降解，容易造成二次污染等缺点，在实际应用中会给土壤造成许多不良影响。针对上述问题，本工作使用了低成本、可降解、低毒性的高分子─二硫代氨基甲酸壳聚糖（DTC-CTS）和聚乙烯醇（PVA）来分别作为土壤修复剂和保水剂，探究了这两类材料在治理重金属污染土壤和增强沙土保水能力方面的效果。具体内容如下：1. 合成了一种含有强螯合基团的壳聚糖衍生物─二硫代氨基甲酸壳聚糖，用红外光谱（IR）、核磁光谱（1H NMR）、X射线衍射光谱（XRD）和元素分析等对产物进行了表征，验证了产物的成功的制备。2. 温室盆栽法的结果表明，在较低的添加量的情况下（0.016%-0.16%)，DTC-CTS可以显著改善污染土壤中拟南芥的生长状况：植物中的Cd含量最高可以降低 50%，生物量和叶绿素的含量也可以恢复到正常条件下的水平。3. 用X射线吸收精细结构谱（X-Ray Absorption fine structure，XAFS）探究了二硫代氨基甲酸壳聚糖（DTC-CTS）与重金属Cd（II）的络合机理。结果表明对于DTC-CTS系列吸附样品，主要是二硫代氨基甲酸基团中的S与Cd（II）发生络合反应，生成了Cd-S键，晶体构型为四面体，Cd（II）在DTC-CTS的表面与DTC-CTS形成了双齿单核的内层复合产物。通过比较不同硫含量的DTC-CTS 与Cd（II）吸附产物的结构参数，可以推测出DTC-CTS 对的Cd（II）的吸附机理不受DTC-CTS含硫量和基团分布密度的影响。4. 选取了不同醇解度的聚乙烯醇（PVA）作为沙土保水剂，并且合成了传统的保水剂—聚丙烯酰胺 (PAM) 作为对照材料，检测了不同的保水剂增强沙土保水性和改善沙土中植物生长状况的效果。结果表明PVA与传统的保水剂PAM一样，都可以起到提高沙土的保水能力，改善沙土中植物的生长状况的效果。同时探究了PVA的醇解度对其提高沙土保水性的影响规律。结果表明，中等醇解度的PVA1795和PVA1797的保水效果最好。通过实验结论，提出了一种需要同时考虑吸水性、在沙土中保持能力和降解性的选择理想高效的治沙保水剂的新标准。 |
| 英文摘要 | The rapid development of industrialization and urbanization has led to serious soil problems in China. Chemical immobilization and adding water retaining agent are common methods for treatment of heavy metal contaminated soils and desertification. However, the traditional chemical additives and water retaining agents usually have disadvantages such as high cost and difficult to degrade, and they may have potential risks to the environment and human. In view of the above problems, we used low-cost, low-toxic and degradable polymer—dithiocarbamate chitosan (DTC-CTS) and poly (vinyl alcohol) (PVA) as soil remediation agent and water retaining agent, respectively. The effect of these two kinds of materials on the treatment of heavy metal contaminated soil and the improvement of the water holding capacity of sandy soil was explored. Details are as follows: 1. Dithiocarbamate chitosan (DTC-CTS) was synthesized by the reaction of carbon disulfide and chitosan, as a new amendment for remediation of cadmium contaminated soils. Its structure was confirmed by FT-IR, 1H NMR, XRD and elemental analysis.2. DTC-CTS was mixed with Cd polluted soils in order to immobilize Cd. Arabidopsis thaliana was planted in the Cd polluted soils as a model plant. The results showed that when DTC-CTS was in low additions（0.016%-0.16%), it could effectively improve the growth of Arabidopsis thaliana. The amount of Cd up taken by Arabidopsis thaliana could be decreased by as much as 50% compared with that grown in untreated Cd contaminated soil samples. The chlorophyll content and the aerial biomass of Arabidopsis is also increased substantially and eventually returned to a level comparable to plants grown in non-contaminated soils, with the addition of DTC-CTS.3. Microscopic structures of Cd（II）surface complexes adsorbed at DTC-CTS were studied using X-ray absorption near edges structure (XANES) spectroscopy and extended X-ray absorption fine structure (EXAFS) spectroscopy. The results showed that Cd adsorption occurs by formation of Cd-S bond with S atom in dithiocarbamate groups in DTC-CTS. The crystal configuration is tetrahedral and Cd（II）interacts with S atoms on the microbial surface by forming a bidentate mononuclear inner-sphere complex. The mechanism of Cd（II）surface complexes adsorbed at DTC-CTS was not affected by the change of sulfur content in DTC-CTS.4. Poly (vinyl alcohol) (PVA) was used as a low-cost and degradable water retention agent in combating with drought and desertification. The commonly used cross-linked hydrogel, polyacrylamide (PAM), was used for comparison. The results showed that PVA was the same as PAM, which could effectively enhance the water retention capacity of sandy soil and the growth of plants in it. The relationship between PVA’s degree of hydrolysis and its water retention performance in sandy soil was also studied. It was found that the middle degree of hydrolysis-PVA 1795 and 1797 had the best performance. Through this study, a few criteria were proposed for the selection of better water retention agent, considering their water absorbency, interaction with sandy soil and degradability. |
| 中文关键词 | 土壤重金属污染 ; 二硫代氨基甲酸壳聚糖 ; 土壤荒漠化 ; 聚乙烯醇 |
| 英文关键词 | Cadmium polluted soil Dithiocarbamate chitosan Desertification Poly (vinyl alcohol) |
| 语种 | 中文 |
| 国家 | 中国 |
| 来源学科分类 | 高分子化学与物理 |
| 来源机构 | 中国科学院化学研究所 |
| 资源类型 | 学位论文 |
| 条目标识符 | http://119.78.100.177/qdio/handle/2XILL650/287729 |
| 推荐引用方式 GB/T 7714 | 尹铮. 高分子在重金属污染土壤修复和保水治沙方面的应用[D]. 中国科学院大学,2016. |
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