Department of Civil Engineering, The University of Hong Kong, Pokfulam, Hong Kong SAR999077, P. R. China.
Environ Sci Technol. 2023 Feb 14;57(6):2548-2556. doi: 10.1021/acs.est.2c07872. Epub 2023 Jan 31.
Surface roughness has crucial influence on the fouling propensity of thin film composite (TFC) polyamide reverse osmosis (RO) membranes. A common wisdom is that rougher membranes tend to experience more severe fouling. In this study, we compared the fouling behaviors of a smooth polyamide membrane (RO-s) and a nanovoid-containing rough polyamide membrane (RO-r). Contrary to the traditional belief, we observed more severe fouling for RO-s, which can be ascribed to its uneven flux distribution caused by the "funnel effect". Additional tracer filtration tests using gold nanoparticles revealed a more patchlike particle deposition pattern, confirming the adverse impact of "funnel effect" on membrane water transport. In contrast, the experimentally observed lower fouling propensity of the nanovoid-containing rough membrane can be explained by: (1) the weakened "funnel effect" thanks to the presence of nanovoids, which can regulate the water transport pathway through the membrane and (2) the decreased average localized flux over the membrane surface due to the increased effective filtration area for the nanovoid-induced roughness features. The current study provides fundamental insights into the critical role of surface roughness in membrane fouling, which may have important implications for the future development of high-performance antifouling membranes.
表面粗糙度对薄膜复合（TFC）聚酰胺反渗透（RO）膜的污染倾向有至关重要的影响。一个普遍的观点是，表面越粗糙的膜更容易受到严重的污染。在本研究中，我们比较了光滑聚酰胺膜（RO-s）和含有纳米空穴的粗糙聚酰胺膜（RO-r）的污染行为。与传统观念相反，我们观察到 RO-s 的污染更严重，这可以归因于其“漏斗效应”导致的通量分布不均匀。使用金纳米粒子进行的额外示踪过滤测试揭示了更具斑块状的颗粒沉积模式，证实了“漏斗效应”对膜水传输的不利影响。相比之下，含有纳米空穴的粗糙膜表现出较低的污染倾向，这可以归因于：（1）由于纳米空穴的存在，减弱了“漏斗效应”，这可以调节水通过膜的传输途径；（2）由于纳米空穴诱导的粗糙度特征增加了有效过滤面积，导致膜表面的平均局部通量降低。本研究深入了解了表面粗糙度在膜污染中的关键作用，这对于高性能抗污染膜的未来发展可能具有重要意义。
