论文总字数：19227字

摘 要

陶瓷膜相比于有机膜具有较大机械强度，稳定的化学性质，良好的耐高温和抗生物能力，被广泛运用于食品、医药、军事和水处理等众多领域。随着膜分离技术在脱盐领域需求的增加，尤其是在造纸、印染、医用和生活废水等许多苛刻条件下脱盐或离子分离，使得对高精度分离膜的需求日益增加，于此同时孔道中离子传输行为的机理模型也急需建立起来，以指导实际的应用体系。

膜孔径在2-10nm之间的TiO₂超滤膜具有较好的离子选择性以及良好的稳定性在膜过滤领域具有很大的应用前景。本课题以溶胶凝胶法制备2nm左右孔径的TiO₂超滤膜来探究离子在纳米孔道中的传输行为。

离子在纳米级孔道内的传递行为，受其表面荷电性影响显著，因此对其介电性质进行准确表征，对探究离子在孔道中传输行为的探究有巨大的指导意义。电化学阻抗谱（EIS）是一种简单无破坏的分析膜层介电性质的方法，并且能在线检测不同盐溶液体系中离子在魔抗中的传递。本章测试了不同浓度的NaCl溶液及MgCl₂溶液在膜中的导电性，并用EIS对各溶液 膜进行阻抗分析，结果表明，由于不同离子在膜层中传输行为的不同，因而在Nyquist图中在高频区出现了膜层的容抗弧。而在电容频率图中，离子在体系中的传递可以分为扩散极化，膜层控制，诱导效应和溶液控制等几个区域。

2nm左右的膜，对其二价离子既有较好的截留性，但对一价离子选择性较差，且随溶液离子浓度增加，截留性能逐渐下降。受到生物离子孔道中，产生一个活性电势来加快或抑制某种离子的传递，本文通过外加电场来调控离子在膜孔道中的传输行为，根据离子价态及其溶液中水合半径的不同，其场效应强度不同，来实现对高价离子的门控效应，以实现对一二价离子的完全分离。本文采用高浓度的混合盐溶液（0.4 M MgCl₂ 0.8 M NaCl）为处理液，通过膜两端施加外电场，Na 和Mg² 在膜孔中的传递通量减小(无论电场方向并且不考虑孔内双电层影响)，并在 2v（定义：膜面侧接正极为正电压）时，Na 由于较小的水合半径和核电荷数数优先占据纳米孔道，阻止了Mg² 的透过，实现了对Mg² 的门控效应。

关键词： 二氧化钛膜 溶胶凝胶法 离子传输 电化学阻抗谱

Abstract

Compared to the organic membranes, Ceramic membranes have advantages on hydrothermal nature, chemical stability, mechanical strength and anti-biological capability, is widely applied in food, medicine, water treatment and military industries. With the increasing demands of membrane separation technology in the field of desalination, especially in many harsh conditions, the desalination or ions separation of papermaking, printing, medical and domestic wastewater，this current stimulates the demand for high precision separation membrane. At the same time, ion channels transmission model and mechanism also need setting up to guide the actual application system.

TiO₂ ultrafiltration membrane with the pore of 2-10nm has a great application potential in the field of membrane separation, because of its great ions selectivity and stability. This work explores ions transmission behavior in nano-channel by preparing TiO₂ ultrafiltration membrane via sol-gel route.

Ion transmission behavior in the charged membrane is closely related to the dialectic parameter of the membrane. Hence, it has great significance on directing the transmission mechanism to characterize its dialectic performance. EIS was simple and non-damaging method to analyze the dialectic performance of the membrane. Through testing the conductivity of NaCl and MgCl₂ solutions with different concentrations and using the IES to analyze the membrane-solution system impedance, a new lobe occurred in the Nyquist diagram of the membrane-solution system because of the difference between Na and Mg² transport behavior in the membrane pore.

The membrane with a pore size about 2nm is favored the monovalent ion transmission and rejected the divalent ions. However，the selectivity decreases gradually with increasing ionic concentration and membrane defects. Illuminated by biological channels where the ion transport can be enhanced or inhibited by generating an active potential，an extra electric field was used to regulate the ion transmission behavior in the nano-channel to realize the gating-effect of high valence ions and perfectly separate the mixed salt solution. In this work, the treating fluid is 0.4 M MgCl₂ 0.8 M NaCl mixed solution. Due to adding an extra electric field (Unconcerned with the direction of the electric field and irrespective of the channel electric double layer )，both of Na and Mg2 transport rate decrease，and with 2 V electric field（ Defined: the membrane face connected to positive pole as positive electric field direction ）, Na ions take over the channels firstly because its smaller hydrated ionic radius and charge number，stop the transmission of Mg2 . In this situation, the gating-effect of Mg2 is realized.

Keywords：TiO₂ membrane；Sol-gel route；Ion transmission；IES ；

目录

摘 要 1

Abstract 2

第一章 文献综述 1

1.1 引言 1

1.2 介孔TiO₂的结构和性质 2

1.3 TiO2膜的运用前景 3

1.4 电场作用下膜的应用 4

1.4.1 电渗析的发展与运用 4

1.4.2 电滤膜 4

1.5离子在纳米孔道内的传输 4

1.5.1 离子在纳米孔道中里的作用力 4

1.5.2 电场作用下离子在纳米孔道中的传输 6

1.6 电场调控离子传输的瓶颈 8

1.7 本课题项目的目的和内容 8

1.7.1 研究目的 8

1.7.2 研究内容 9

第二章 实验部分 10

2.1 实验原料 10

2.2 主要仪器和设备 10

2.3 实验方法 10

第三章 结果与讨论 10

3.1离子扩散和混合盐溶液的数据分析 13

3.2电化学阻抗普分析 16

3.3 Zeta电位分析 17

第四章 结论 19

参考文献 20

致 谢 22

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