论文总字数：25948字

摘 要

根据国家发布的核电中长期发展规划，至2020 年，我国将建成运行4000万千瓦核电机组，此外，内陆核电厂的建设也已纳入国家的核电发展规划。核能的快速发展不可避免地会产生大量中低水平放射性废水，一旦处理不慎将会对环境和人体健康造成极大的危害。中、低水平放射性废水中通常含有的⁶⁰Co、¹³⁷Cs和⁹⁰Sr是比较常见的放射性核素。因此采用适当的方法去除中、低水平放射性废液中的⁶⁰Co、¹³⁷Cs和⁹⁰Sr成为研究者们的关注点。

中、低水平放射性废水的传统处理方法有化学沉淀法、蒸发浓缩法和离子交换法，这些方法都有各自的优点和缺点；而膜技术作为一种新兴的分离技术，因其具有能耗低、不需化学反应即可完成分离过程、分离效率高等优点而备受青睐。

本文采用钛锆复合陶瓷纳滤膜（MWCO=500 Da）去除模拟中、低放射性废水中的钴、铯和锶离子。主要考察了溶液pH、操作压力、初始离子浓度对Co² 、Cs 和Sr² 截留率和膜通量的影响，并研究了钛锆复合纳滤膜在中低放射性废水体系中的稳定性。通过实验发现，三种离子截留率随着操作压力的升高而增大，到P=0.9 MP时基本上不再变化；膜通量基本不受压力影响。pH变化时，截留率在一定pH范围内先降低后升高，等电点附近（pH=7）达到最小值；pH=3的情况下，三种离子的截留率均达到最高，Co² 和Sr² 的截留率均达到99%以上，Cs 达到75%，膜通量基本不变。三种离子截留率以及膜通量随着初始离子浓度的增加而降低，在初始离子浓度为200 ppm时膜通量骤减，这可能是因为膜表面形成了一层较完整的污染层，使得膜通量下降。考察钛锆复合纳滤膜在中低放射性废水体系中的稳定性时，发现随着运行时间的延长，三种离子的截留率及膜通量基本稳定。

关键词：陶瓷纳滤膜 表征 中低水平放射性废水 离子截留

Application of ceramic nanofiltration membrane for simulative radioactive effluent treatment

Abstract

According to Chinese medium and long-term development plan, to 2020, the capacity up to 40 million kW nuclear power plant will be built in our country. Moreover, the construction of the inland nuclear power plant have been considered into the national nuclear power development plan. The rapid development of nuclear power will inevitably produce a large number of low and medium level radioactive wastewater, which will cause great harm to environment and human health, in the absence of effective treatment. Low and medium level radioactive wastewater commonly contains Co² , Cs and Sr² radionuclides. So adopting an appropriate method to remove Co² , Cs and Sr² is attracting more and more intrest around the reseachers.

The traditionalmethods of low and medium level radioactive wastewater treatment include chemical precipitation, evaporation concentration and ion exchange. These methods have their own application scopes and weakness. As a new separation technology, membrane technology is gaining more attention for its energy consumption, no chemical reaction and high separation efficiency.

In this thesis, Ti/Zr composite nanofiltration membrane (MWCO=500 Da) was used to remove the cobalt ,cesium and strontium ions in the low-level radioactive wastewater. The influence of pH, operating pressure, initial concentration on membrane flux and retention rate as well as the stability were investigated. It’s demonstrated that: retention rate of three ions increased with the elevation of operating pressure. When the transmembrane pressure is equal to 0.9MPa, the membrane flux changed slightly. With the variation of pH, retention rate firstly rised but fell down in the range of the pH then. When pH=7( isoelectric point), retention rate was achieved. Under the condition of pH = 3, retention rates of three kinds of ions achieved the highest level. Co² and Sr² achieved up to 99%, and Cs was 75% respectly. Retention rate of three ions and membrane flux decreased with the increase

of initial concentration. There is a significant flux decline around the concentration of 200 ppm. It may due to the formation of the ions fouling layer in the membrane surface, which reduced the membrane flux. With the operation time extended, retention rates of three ions and the membrane flux are almost stable in a long running term by investigating the stability of Ti/Zr composite nanofiltration membrane in the system of low and medium level radioactive wastewater .

Keyword: Ceramic nanofiltration membrane; Characterization; Low and medium level radioactive wastewater; Ions retention

目 录

摘 要 I

Abstract II

第一章 文献综述 1

1.1 概述 1

1.2 陶瓷纳滤膜表征技术 1

1.2.1 显微镜法 1

1.2.2 溶质截留法 2

1.2.3 渗透孔度法 3

1.3 核电站放射性废水的来源及组成 3

1.3.1 放射性废水的来源 3

1.3.2 放射性废水的分类 5

1.3.3 核电站放射性废水中的常见核素 5

1.4 放射性废水处理方法的研究进展 6

1.4.1 化学沉淀法 6

1.4.2 蒸发浓缩法 6

1.4.3 离子交换法 7

1.4.4 膜分离 7

1.5 纳滤膜处理放射性废水的研究进展 8

1.6 研究目的及内容 9

第二章 钛锆复合纳滤膜的表征 10

2.1实验部分 10

2.1.1 实验材料及仪器 10

2.1.2 表征方法 10

2.2 结果与讨论 11

2.2.1 膜的微观形貌 11

2.2.2 膜的纯水通量及截留分子量 12

2.3 本章小结 13

第三章 钛锆复合纳滤膜在模拟放射性废水中的应用研究 15

3.1 实验部分 15

3.1.1 实验试剂及仪器 15

3.1.2 实验方法 15

3.1.3 实验流程 15

3.2 结果与讨论 16

3.2.1 钛锆粉体等电点的测定 16

3.2.2 pH值对模拟放射性废水处理效果的影响 17

3.2.3 压力对模拟放射性废水处理的影响 19

3.2.4 初始离子浓度对纳滤膜处理效果的影响 21

3.2.5 陶瓷纳滤膜在模拟放射性废水体系中的稳定性 22

3.3 本章小结 24

第四章 结论与展望 25

4.1 结论 25

4.2 展望 25

参考文献 27

致谢 29

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