铀尾矿区铀在土壤中的吸附与迁移规律研究

发布时间：2018-05-07 04:30

  本文选题：土壤 + 铀污染　； 参考：《东华理工大学》2017年硕士论文

【摘要】：本文以南方某尾矿库周边土壤为研究对象,通过实验测定研究区周边土壤pH值、含水量、有机质、CEC等理化性质,通过静态吸附实验,考察了初始pH、初始铀浓度、吸附时间及有机质等因素对土壤吸附铀的影响,通过动态迁移实验,考察了不同淋滤量及pH值下铀在土壤中迁移转化及形态分布特征,并通过对实验数据拟合探讨土壤吸附铀的机理。主要结论如下:(1)研究区土壤样品pH为4.63,呈酸性;含水率为1.39%,含水率偏高;有机质含量为46.98g/kg;阳离子交换量(CEC)为46.98cmol/kg;总铀的含量为3.21μg/g,属于铀污染土壤。(2)静态吸附实验研究表明:初始pH、初始铀浓度、吸附时间、有机质、磷酸盐、土壤粒径这几种因素对土壤吸附铀的影响极其显著;重金属离子中Cu、Cd、Pb、Zn抑制土壤对铀的吸附,K基本不影响土壤对铀的吸附;在常温下,温度对土壤吸附铀的能力没有显著的影响。在吸附温度为25℃条件下,100目的土壤样品0.5g,在初始pH为5.0,吸附时间达8h以上,初始铀浓度为10mg/L的条件下,吸附率达到最大值,吸附率为96.36%,吸附量为0.1927mg/g。(3)动态迁移实验研究表明:经不同淋滤量及不同pH淋滤液淋滤后,淋滤量与pH的不同使铀在土壤中迁移不同的距离,铀在土壤中的形态分布规律为残渣态无定型铁锰氧化物/氢氧化物结合态碳酸盐结合态有机质结合态可交换态(包括水溶态)晶质铁锰氧化物/氢氧化物结合态,且土壤中残渣态铀及无定型铁锰氧化物/氢氧化物结合态铀均略高于原土壤,晶质铁锰氧化物/氢氧化物结合态铀含量占比均为最小,其余三种形态铀分布不均。(4)吸附机理分析研究表明:土壤样品吸附前后结构保持相对完整,土壤表面形貌特征发生一定变化,土壤表面存在着大量的C-N、C-O、C-H等带有负电荷的官能团,增强土壤对铀酰离子的静电吸附能力。土壤对铀的吸附过程以单分子层吸附为主,多分子层吸附、物理吸附和化学吸附并存,以Langmuir等温吸附模型(R2=0.9954)、准二级吸附动力学模型(R2=0.9977)来描述其吸附过程较为合适,且该吸附过程为放热过程可自发进行。
[Abstract]:In this paper, the physical and chemical properties of the soil around a tailings reservoir in the south of China were studied. The physical and chemical properties of the soil such as pH value, water content, organic matter CEC and so on were determined by experiments. The initial pH and initial uranium concentration were investigated by static adsorption experiment. The effects of adsorption time and organic matter on the adsorption of uranium in soils were studied by dynamic migration experiments. The migration, transformation and morphological distribution of uranium in soils with different leaching amounts and pH values were investigated. The mechanism of uranium adsorption by soil was discussed by fitting the experimental data. The main conclusions are as follows: (1) the pH of soil samples in the study area is 4.63, which is acidic, the moisture content is 1.39 and the water content is on the high side. The content of organic matter is 46.98 g / kg; the cation exchange capacity (CEC) is 46.98 cmol / kg; the total uranium content is 3.21 渭 g / g, belonging to uranium-contaminated soil. The static adsorption experiments show that: initial pH, initial uranium concentration, adsorption time, organic matter, phosphate, The influence of soil particle size on the adsorption of uranium is extremely significant, and the inhibition of adsorption of uranium by Cu ~ (2 +) CD ~ (2 +) Pb ~ (2 +) Zn in heavy metal ions has little effect on the adsorption of uranium by soil, while temperature has no significant effect on the ability of soil to adsorb uranium at room temperature. Under the conditions of adsorption temperature of 25 鈩，

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