论文总字数：38679字

摘 要

重金属污染是环境污染的突出方面。土壤对地下水中的重金属元素具有富集作用，重金属元素在土壤中积累，对动植物和人类的生存和健康造成了极其负面的影响。为了探讨不同酸碱性环境下的饱和土离子沉淀效应，本文对高岭土在不同酸碱性环境下的压缩固结特性和锌离子运移规律进行了试验研究。通过一组压缩固结试验和一组一维扩散试验，探究不同氢氧化锌沉淀量对土壤压缩固结特性的影响和锌离子在不同酸碱性高岭土柱中的运移规律。

试验证明：

1）氢氧化锌沉淀量会对土壤的压缩性产生影响，高岭土的压缩系数、压缩指数随沉淀量的增加而减小，而压缩模量随沉淀量增大而增大，这说明氢氧化锌沉淀会使土壤的压缩性降低，使高岭土更不易压缩；

2）氢氧化锌沉淀也会对高岭土的固结特性产生影响，大多数情况下，氢氧化锌沉淀会使高岭土固结系数增大，固结速度变快，但是也有例外的情况，0.005mol/L氢氧化锌悬浊液制备的高岭土在400kPa荷载条件下时固结系数比素高岭土和无沉淀的0.05mol/L硝酸锌制备的高岭土都更小，固结速度更慢，不过这一结果的准确性还需要进一步的试验验证；

3）碱性环境会在一定程度上促进锌离子在土柱中的运移，并且使锌离子生成氢氧化锌沉淀，因为碱性土柱会使锌离子反应沉淀，促进了土柱对锌离子的吸收。PHREEQC模拟表明，在碱性土柱中的氢氧化锌饱和指数SI有大于0的时期，说明该时期内土柱中的锌离子趋向于沉淀。

关键词 锌离子；酸碱性；离子运移；高岭土；饱和

Abstract

Heavy metal pollution is a serious environmental pollution. The soil has an enrichment effect of heavy metals in groundwater. Heavy metals can be accumulated in the soil, resulting in an extremely negative impact on wildlife and human survival and health. In order to explore the ion precipitation effect of saturated kaolin soil in different pH environment, experiments were done at different pH environment to study the consolidation characteristics and zinc ion migration. The experiment proves that the precipitation has great influence on soil consolidation characteristics, but has less effect on compression characteristics; alkaline environment will promote zinc ion in soil column in a certain extent.

Experiments have proved, that

1) the amount of zinc hydroxide precipitation effects soil compressibility. The compression coefficient and compression index decrease with the increase of amount of precipitation, and the compressive modulus increases with precipitation, indicating that zinc hydroxide precipitate decreases the soil compressibility and makes the kaolin more difficult to be compressed.

2) zinc hydroxide precipitation will affect the consolidation behavior of kaolin. In most cases, zinc hydroxide precipitation will increase the coefficient of consolidation of kaolin. As a result, consolidation speed becomes faster. But there are exceptions, 0.005mol/L zinc hydroxide suspension of kaolin under 400kPa load has a larger consolidation coefficient than plain kaolin and precipitation of 0.05 mol /L nitrate kaolin and its consolidation speed is slower, but the accuracy of the results need further experimental verification

3) alkaline environment will promote the migration of zinc in the soil column in a certain extent, and the zinc ions will form zinc hydroxide precipitation, because the alkaline soil column will make reaction of zinc ion precipitation, promote the soil column of zinc ion absorption. PHREEQC simulations show that there is a period in alkaline soil column when hydroxide zinc saturation index (SI) is larger than 0, which shows that in the period zinc in the soil column tend to form precipitation.

Key words Zinc ion, pH, Ion transport, Saturated kaolin

目录

摘要 I

Abstract II

第一章 绪论 1

1.1 研究背景和研究意义 1

1.2 研究现状分析 2

1.3 目前存在的问题和本文研究的主要内容 3

1.4 试验技术路线 4

1.5 可行性分析 4

第二章 试验材料与方案 5

2.1 概述 5

2.2 试验材料 5

2.2.1高岭土 5

2.2.2 氢氧化钠 6

2.2.3硝酸锌 6

2.2.4氯化氢 7

2.3 试验内容与方法 7

2.3.1 密度、含水率试验 7

2.3.2 固结试验 8

2.3.3 扩散试验 9

2.3.4 PHREEQC模拟 10

2.4本章小结 10

第三章 压缩固结试验结果 11

3.1土样基本性质 11

3.2 固结试验结果 11

3.2.1 压缩特性 11

3.2.2 固结性质 13

3.3 本章小结 17

第四章 扩散试验结果 18

4.1 土样基本性质 18

4.2 扩散试验结果 19

4.2.1 概述 19

4.2.2 电导率变化规律 19

4.2.3 pH值变化规律 20

4.2.4 锌离子浓度变化规律 21

4.3.5 PHREEQC模拟结果 22

4.3 本章小结 24

第五章 分析与讨论 25

5.1 氢氧化锌沉淀对高岭土压缩与固结性质的影响 25

5.2 锌离子在不同pH值高岭土柱中的运移规律 25

5.3 本章小结 26

第六章 结论 27

6.1 试验结论 27

6.2 本试验的不足和需要进一步研究的问题 27

致谢 29

参考文献 30

附录 31

1. 数据 31

1.1 固结试验数据 31

1.2扩散试验参数 35

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