Abstract There has been an argument on the influence of membrane hydrophilicity on permeability between experimental and simulation works. Theoretical work finds that the membranes have a characteristic called a threshold pressure drop (ΔPT). Strongly hydrophobic membranes exhibit extremely high ΔPT, making membranes less wettable and consequently less permeable. In order to experimentally investigate the influence of wetting states of membranes, determined by membrane hydrophilicity, on permeability, we prepared a series of membranes with progressively changing hydrophilicities by atomic layer deposition (ALD) of TiO2 on polytetrafluoroethylene membranes while keeping the pore size unchanged. In addition, adding ethanol into the water and raising the operating pressure drops are also selected to improve the wetting degrees. The experimental results verify the presence of ΔPT for all membranes and the hydrophobic membranes having higher ΔPT. Since the hydrophilic membranes have better wetting degrees but higher transport resistance, there should be an optimized hydrophilicity, which is found to be determined by the feed solution and the operating ΔP. The optimized hydrophilic modification is the one when the membrane can be just adequately wetted by the feed solution at the target operating pressure drops. Highest water permeability is expected to be obtained at a moderate hydrophilicity, neither at the extreme hydrophilicity nor at the extreme hydrophobicity.

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膜亲水性对水渗透性的影响：桥接模拟的实验研究

摘要 在实验和模拟工作之间，关于膜亲水性对渗透性的影响存在争论。理论工作发现膜具有称为阈值压降 (ΔPT) 的特性。强疏水性膜表现出极高的 ΔPT，使膜的润湿性较差，因此渗透性较差。为了通过实验研究由膜亲水性决定的膜润湿状态对渗透性的影响，我们通过 TiO2 在聚四氟乙烯膜上的原子层沉积 (ALD) 制备了一系列亲水性逐渐变化的膜，同时保持孔径不变。此外，还选择在水中加入乙醇，提高操作压降，以提高润湿度。实验结果验证了所有膜和具有较高 ΔPT 的疏水膜都存在 ΔPT。由于亲水膜具有更好的润湿度但具有更高的传输阻力，因此应该有一个优化的亲水性，这是由进料溶液和操作ΔP决定的。优化的亲水改性是当膜在目标操作压降下刚好被进料溶液充分润湿时的改性。预计在中等亲水性下获得最高的透水性，无论是在极端亲水性还是极端疏水性下。应该有一个优化的亲水性，这是由进料溶液和操作 ΔP 决定的。优化的亲水改性是当膜在目标操作压降下刚好被进料溶液充分润湿时。预计在中等亲水性下获得最高的透水性，无论是在极端亲水性还是极端疏水性下。应该有一个优化的亲水性，这是由进料溶液和操作 ΔP 决定的。优化的亲水改性是当膜在目标操作压降下刚好被进料溶液充分润湿时。预计在中等亲水性下获得最高的透水性，无论是在极端亲水性还是极端疏水性下。