论文总字数：18355字

摘 要

化工生产过程中，由于有机溶剂操作的不可密闭性，从而避免不了会产生或排放一些挥发性有机物（VOCs）。这些排放的 VOCs是雾霾、光化学污染和破坏臭氧层的元凶之一，并且会对人体造成巨大伤害，严重影响经济和社会发展。为此，研究人员开发了多种VOCs分离回收方法，来缓解环境的压力。其中，基于膜法VOCs分离回收技术，由于不会对环境造成二次污染，还具有低能耗，高收率等优点，被认为是最有前景的分离技术之一。

膜法VOCs分离过程中，膜分离性能优劣是工业化应用的关键。根据溶解扩散机理，膜性能由溶解性和扩散性两部分组成。其中扩散系数检测是由于VOCs气体的可凝性等特点，是该领域的难点。同时扩散系数的准确测定将为膜分离机理的解释提供理论基础。因此本文以醇类/氮气为研究对象，以时间延迟法为基本原理，恒容变压法为基本实验方法，研究了不提供操作条件等因素对PDMS复合膜扩散系数的影响规律。结果显示VOCs/N₂混合物分离过程中，VOCs和N₂间存在耦合作用。VOCs的可冷凝性越强，VOCs的通量越大而N₂的通量越小。温度升高提升了扩散性而抑制了吸附性，因此VOCs的通量和选择性随着温度的升高下降，N₂的通量显著上升。

关键字：有机挥发物 PDMS复合膜 膜分离 蒸汽渗透 扩散系数

Determination of VOC Diffusion Coefficient of PDMS Composite Film

ABSTRACT

In the chemical production process, due to the non-sealing nature of organic solvent operation, some volatile organic compounds (VOCs) will not be produced or emitted. These emitted VOCs are one of the culprits of smog, photochemical pollution and destruction of the ozone layer, and cause great harm to the human body, seriously affecting economic and social development. To this end, the researchers developed a variety of VOCs separation and recovery methods to ease the pressure on the environment. Among them, based on membrane VOCs separation and recovery technology, because it does not cause secondary pollution to the environment, it also has the advantages of low energy consumption and high yield, and is considered to be one of the most promising separation technologies.

In the separation process of membrane VOCs, the membrane separation performance is the key to industrial application. According to the dissolution diffusion mechanism, the film properties are composed of two parts, solubility and diffusivity. Among them, the diffusion coefficient detection is due to the condensability of VOCs gas, which is a difficult point in this field. Simultaneous determination of the diffusion coefficient will provide a theoretical basis for the interpretation of the membrane separation mechanism. Therefore, the alcohol/nitrogen gas is taken as the research object, and the time delay method is taken as the basic principle. The constant volume and pressure transformation method is the basic experimental method. The influence of the operating conditions and other factors on the diffusion coefficient of PDMS composite membrane is studied. The results show that there is a coupling between VOCs and N2 during the separation of VOCs/N2 mixture. The stronger the condensability of VOCs, the greater the flux of VOCs and the smaller the flux of N2. The increase in temperature increases the diffusivity and inhibits the adsorptivity, so the flux and selectivity of VOCs decrease with increasing temperature, and the flux of N2 increases significantly.

Key Words：VOCs PDMS Membrane Vapor permeation Diffusion coefficient

目 录

摘要 I

ABSTRACT II

第一章 文献综述 1

1.1 VOCs回收背景 1

1.1.1 VOCs的来源 1

1.1.2 VOCs的危害 1

1.1.3回收的意义 2

1.2 VOCs回收方法 2

1.3 膜分离技术 3

1.3.1 膜分离机理 3

1.3.2 膜分离材料 4

1.3.3 膜回收VOCs性能评价 5

1.4 恒容变压法 5

1.5 研究目的 6

第二章 实验 7

2.1 引言 7

2.2 实验部分 7

2.2.1 实验药品和设备 7

2.2.2 实验装置和流程 7

2.3 扩散系数的测定 10

2.4 溶解系数的测定 11

第三章 结果与讨论 12

3.1 膜的表征 12

3.2 膜性能参数结果分析 12

3.2.1 原料气种类对膜性能影响 12

3.2.2 进料浓度对膜性能影响 15

3.2.3 进料温度对膜性能影响 16

第四章 结论与展望 21

4.1 结论 21

4.2 展望 21

参考文献 22

致谢 25

第一章 文献综述

1.1 VOCs回收背景

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