将水的扩散与模型反透聚胺与受控交联密度的性能相关联
Velencia J Witherspoon1,2, Kanae Ito1,3, Chad R Snyder1
1Materials Science and Engineering Division, National Institute of Standards and Technology, Gaithersburg, MD.
Journal of membrane science
|July 19, 2023
概括
研究人员修改了聚胺网络,以改善反透膜. 由于氨基相互作用增加,减少交叉链密度出乎意料地减缓了水的扩散,为更好的海水淡化膜设计提供了见解.
科学领域:
- 材料科学 材料科学 材料科学
- 化学工程是化学工程的重要组成部分.
- 膜科学 膜科学 膜科学
背景情况:
- 聚胺 (PA) 分离层对于用于海水淡化的反透膜至关重要.
- 优化PA网络结构是提高水流和盐排斥的关键.
- 控制交叉连接密度是调整PA膜性能的主要策略.
研究的目的:
- 系统地降低聚胺网络的交叉链密度,使用双功能模拟.
- 调查减少交叉连接对水扩散和膜性能的影响.
- 为了确定高性能RO膜的设计原则.
主要方法:
- 通过用异甲基化物替代三化来合成具有不同交叉链密度的PA网络.
- 复合膜的制造和水流和盐排斥的评估.
- 使用准弹性中子散射 (QENS) 量化微观水扩散.
主要成果:
- 通过将交叉链密度降低50% (15mol%二功能模拟),自由氨基含量和网络胀翻了一番.
- 尽管胀增加,但由于水的翻译扩散速度减慢了五倍,水的透率下降了30%.
- QENS显示,水扩散仅限于短长度尺度 (<5-6 Å),并且随着氨基相互作用的增加而显著减缓.
结论:
- 在PA网络中交叉连接密度的降低导致水的扩散速度减慢,这与基于膨胀的预期相反.
- 增加的自由氨基含量增强了水-氨基相互作用,阻碍了水分子的运动.
- 了解扩散封闭和链相互作用为先进的RO膜提供了关键的设计线索.
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