溶胀辊轧法PVDF膜表面的疏水强化：溶胀剂的影响

doi:10.16085/j.issn.1000-6613.2020-2364

摘要/Abstract

摘要：

提出了一种简便、低成本的聚偏氟乙烯（PVDF）微孔膜表面疏水增强方法——溶胀辊轧法，以微结构辊筒对表面喷涂溶胀剂的PVDF成品微孔膜辊轧后，采用浸没凝胶法成膜。以N-甲基吡咯烷酮/水（非溶剂）为溶胀体系，采用扫描电子显微镜（SEM）、原子力显微镜（AFM）、水接触角（WCA）、最大孔径、平均孔径、N₂通量、耐磨性、液体穿透压（LEP）等表征手段，系统地研究了溶胀剂体系、溶胀剂容量对PVDF微孔膜结构与性能的影响。结果表明：辊轧膜表面呈现微米-亚微米层次特征，溶胀辊轧操作起到了疏水增强、透过能力提升的效果。溶胀剂中水（非溶剂）质量分数为6%、喷涂密度为0.03mL/cm²时，膜性能最优。连续运行30h的真空膜蒸馏（VMD）对比实验表明，辊轧膜较未辊轧膜具有更高的产水通量、脱盐率及更好的耐污染性能。该方法为低成本、连续化进行成品膜表面疏水强化提供了一种新选择。

关键词: 聚偏氟乙烯, 膜, 超疏水, 模塑, 浸没-凝胶法, 脱盐

Abstract:

A simple and low-cost method for enhancing the hydrophobicity of PVDF microporous membrane surface——swelling embossed method was proposed. The membrane was made by immersion gel after rolling the PVDF microporous membrane with microstructure roller. The water (non-solvent) of N-methyl pyrrolidone was a swelling agent. The influence of the structure and properties of PVDF microporous membrane characterized by SEM, atomic force microscope (AFM), contact angle, maximum pore size, average pore size, N₂ flux, wear resistance and liquid entry pressure. The results indicated that the surface of the embossed membrane presented micron-submicron hierarchical features, the operation of swelling rolling had enhanced hydrophobicity and improved permeability, and thus had great hydrophobic stability. When the mass fraction of water (non-solvent) in the swelling agent was 6% and the spray density was 0.03mL/cm², the performance of the membrane was the best. The contrast experiment of continuous operation of 30h vacuum membrane distillation (VMD) showed that the embossed membrane had higher penetration flux and salt rejection rate and better pollution resistance than unembossed. This method provided a new option for low-cost and continuous hydrophobic strengthening of the surface of the finished membrane.

Key words: polyvinylidene fluoride (PVDF), membrane, super-hydrophobic, molding, immersion precipitation, desalination

中图分类号:

TQ028.8

燕国飞, 杨振生, 李春辉, 王志英, 李浩. 溶胀辊轧法PVDF膜表面的疏水强化：溶胀剂的影响[J]. 化工进展, 2021, 40(11): 6270-6277.

YAN Guofei, YANG Zhensheng, LI Chunhui, WANG Zhiying, LI hao. Hydrophobic strengthening of the surface of PVDF membrane by swelling rolling: the influence of swelling agent[J]. Chemical Industry and Engineering Progress, 2021, 40(11): 6270-6277.

图/表 14

图1 溶胀辊轧法PVDF微孔膜的制备过程

表1 溶胀辊轧法PVDF微孔膜的不同制备条件

膜	溶胀剂中水质量分数/%	喷涂密度/mL·cm^-2	辊轧情况
M-0（成品膜）	—	—	—
M-1	6	0.03	未辊轧
M-2	4	0.01	辊轧
M-3	4	0.03	辊轧
M-4	4	0.05	辊轧
M-5	6	0.01	辊轧
M-6	6	0.03	辊轧
M-7	6	0.05	辊轧

图2 N2通量测量装置

图3 PVDF微孔膜的耐磨性测试

表2 原料液组成

化学成分	浓度/g·L^-1
NaCl	26.72
MgSO₄	3.25
MgCl₂	2.26
CaCl₂	1.15
KCl	0.72

图4 VMD实验流程示意图

图5 PVDF微孔膜的SEM图

图6 PVDF微孔膜的AFM图像及粗糙度

图7 PVDF微孔膜的水接触角和滚动角

图8 PVDF微孔膜的空气接触分数M-2、M-3、M-4：水质量分数为4%，喷涂密度分别为0.01mL/cm2、0.03mL/cm2、0.05mL/cm2。M-5、M-6、M-7：水质量分数为6%，喷涂密度分别为0.01mL/cm2、0.03mL/cm2、0.05mL/cm2

图9 PVDF微孔膜的不同性能

图10 在不同摩擦次数下的WCA和SA

图11 PVDF微孔膜的液体穿透压

图12 PVDF微孔膜的VMD实验

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