This paper investigates the relationship between roughness and fouling in reverse osmosis (RO) through specially designed experimental protocols and computational fluid dynamics (CFD) studies. Conventional polyamide thin-film composite membranes with a ridge-and-valley structure and an emerging type of smooth membranes are prepared. A wide range of foulants are used, and fouling under static, crossflow, and RO conditions are tested. Feature size on the membrane surface is important when foulants and the microscale structure show a similar size, and otherwise membrane-foulant interactions govern the static attachment. Under crossflow mode, fouling on the ridge-and-valley surface is not reduced to the same extent as that on smooth membranes, with the insufficient vortices in the valley region being identified as the key factor by CFD studies. In RO, uneven flux distribution as confirmed by gold nanoparticle filtration is also found to account for the much higher fouling rate of conventional membranes. Our study then suggests two strategies to design next-generation fouling-resistant RO membranes via structural optimization: first, a smooth selective layer should be maintained to ensure uniform flux distribution; second, one may mimic nature to fabricate patterned porous membranes as the support, so that it optimizes hydrodynamics while maintaining even fluxes.

中文翻译：

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了解反渗透中的粗糙度与结垢关系：机理与意义。

本文通过专门设计的实验方案和计算流体力学（CFD）研究，研究了反渗透（RO）中粗糙度与结垢之间的关系。制备具有脊-谷结构和新兴类型的光滑膜的常规聚酰胺薄膜复合膜。使用了多种污垢，并测试了在静态，错流和RO条件下的污垢。当污垢物和微尺度结构显示相似的大小时，膜表面的特征尺寸非常重要，否则膜污垢的相互作用将控制静态附着。在错流模式下，脊和谷表面的污垢减少程度不及光滑膜上的污垢程度，CFD研究将山谷区域的涡旋不足确定为关键因素。在RO中 还发现，通过金纳米颗粒过滤确认的通量分布不均，可解释传统膜的结垢率高得多。然后，我们的研究提出了两种通过结构优化设计下一代耐污染反渗透膜的策略：首先，应保持平滑的选择层，以确保通量分布均匀。第二，可以模仿自然来制造带图案的多孔膜作为载体，从而在保持均匀通量的同时优化流体力学。应保持光滑的选择层，以确保均匀的通量分布；第二，可以模仿自然来制造带图案的多孔膜作为载体，从而在保持均匀通量的同时优化流体力学。应保持光滑的选择层，以确保均匀的通量分布；第二，可以模仿自然来制造带图案的多孔膜作为载体，从而在保持均匀通量的同时优化流体力学。