皂角苷对土壤中稀土元素淋洗效果的实验研究

发布时间：2018-06-06 10:17

本文选题：生物表面活性剂 + 皂角苷　；参考：《江西理工大学》2017年硕士论文

【摘要】：近年来,由于稀土资源的大规模开发,以及农用稀土的使用,导致稀土元素矿区及周边土壤环境中累积,由于植物吸收利用导致农产品稀土超标,并且通过食物链传递引起人体健康风险。目前污染土壤治理技术中,土壤淋洗具有见效快、彻底移除污染物等优点,使其在污染土壤的治理领域具有良好的应用前景。淋洗剂的选择与开发是土壤淋洗技术应用最关键的问题,生物表面活性剂具有低毒性、可生物降解、对土壤破坏小等优点,成为土壤淋洗技术研究重点。本文以La、Ce、Y和Eu为目标污染物,探讨皂角苷对土壤中稀土元素的淋洗效果及作用机理。采用振荡淋洗实验,探讨皂角苷浓度、淋洗液pH、土液比、淋洗时间等因素对淋洗效果的影响。通过土柱淋洗实验,探讨皂角苷对土壤中稀土元素La、Ce、Y和Eu的动态淋洗效果。通过分析皂角苷在土壤中的吸附行为、红外光谱分析、离子交换平衡实验等探讨皂角苷与稀土元素的作用机理。主要研究结论如下:(1)通过振荡淋洗实验,得出淋洗污染土壤中La、Ce、Y和Eu的最适条件:皂角苷浓度为25 g·L-1、pH=5.5、土液比为1:40、淋洗时间为6h、无电解质共存,皂角苷对La、Ce、Y和Eu的淋洗率分别为58.05%、57.78%、64.43%、91.97%。(2)土柱淋洗实验的结果表明,皂角苷对土壤中的稀土有较好的淋洗效果。25g·L-1皂角苷溶液对La、Ce、Y和Eu的淋洗效率分别为35.26%、26.07%、31.48%和30.85%,累积淋洗量分别为58.60 mg·kg-1的La、51.16 mg·kg-1的Ce、24.66mg·kg-1的Y和34.47 mg·kg-1的Eu。四种元素的土柱淋洗效果均低于振荡淋洗效果。通过淋洗前后土壤中稀土元素形态分析,皂角苷淋洗主要去除稀土的弱酸可提取态,其次为可还原态。淋洗后土壤中的稀土从与土壤结合较松散的形态转化为土壤结合较紧密的结合形态,增加了土壤的稀土元素的稳定性,降低了稀土在土壤中的生物利用性及其潜在危害。(3)通过对比皂角苷与稀土元素反应前后的红外光谱图,证明了皂角苷与稀土元素通过皂角苷分子中的羧基基团与稀土离子反应生成了新的配位化合物,并通过离子交换平衡法测定了皂角苷与La、Ce、Y、Eu生成了配位比为1:1的配位化合物。皂角苷吸附土壤中稀土元素的机理可以被归纳为降低界面张力、增溶、配位等多种作用的结合。
[Abstract]:In recent years, the large-scale development of rare earth resources, as well as the use of rare earth in agriculture, has led to the accumulation of rare earth elements in the mining area and the surrounding soil environment. Because of the absorption and utilization of the plants, the rare earth of the agricultural products is exceeding the standard, and the health risk of the human body is transmitted through the food chain. The selection and development of the leaching agent is the most important problem in the application of soil leaching technology. The bioactive agent has the advantages of low toxicity, biodegradation and small damage to soil, which has become the key point of soil leaching technology. This paper is based on La, Ce, Y. And Eu as the target pollutant, the effect and mechanism of the leaching of rare earth elements in soil by saponins were discussed. The influence of factors such as the concentration of saponins, pH, soil liquid ratio and leaching time on the leaching effect were investigated by oscillatory leaching experiment. The dynamic drenching of La, Ce, Y and Eu in soil was investigated by soil column leaching experiment. The main research conclusions are as follows: (1) the optimum conditions for La, Ce, Y and Eu in contaminated soil are obtained by oscillating leaching experiments: the concentration of saponin is 25 g. L-1, pH=5.5, and soil. The liquid ratio is 1:40, the leaching time is 6h, no electrolyte coexist, the leaching rate of saponins to La, Ce, Y and Eu are 58.05%, 57.78%, 64.43%, 91.97%. (2) soil column leaching experiment results show that saponin has better leaching effect on rare earth in soil.25g. L-1 saponins solution to La, Ce, Y and Eu leaching efficiency is 35.26%, 26.07%, 31.48% respectively. And 30.85%, the cumulative leaching amount is 58.60 mg. Kg-1 La, 51.16 mg. Kg-1 Ce, 24.66mg. Kg-1 Y and 34.47 mg. Kg-1 Eu. four elements of the soil column washing effect is lower than the oscillation leaching effect. Original state. After leaching, the rare earth in soil is converted from a loose combination with the soil into a compact combination of soil combination, which increases the stability of the rare earth elements in the soil and reduces the bioavailability and potential hazards of rare earth elements in the soil. (3) by comparing the infrared spectra before and after the reaction of saponins and rare earth elements, it is proved that A new coordination compound was formed by the reaction of saponin and rare earth elements through the carboxyl groups of saponin molecules with rare earth ions. The coordination compounds of saponins with La, Ce, Y and Eu were determined by the ion exchange equilibrium method. The mechanism of the adsorption of rare earth elements in soil by saponins can be induced to reduce the interface. The combination of various functions, such as tension, solubilization, coordination and so on.
【学位授予单位】：江西理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：X53

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