Membrane technologies such as nanofiltration membrane are utilized for treatment of water resources. In this study, MnO₂ nanotubes were prepared through hydrothermal process, and then, the inner surface of nanotubes was functionalized through a novel procedure with different polymers (polydopamine and polystyrene) to alter their inner diameter. Then, the neat and modified nanotubes were used in the synthesis of thin-film nanocomposite (TFN) membranes and their performances in terms of permeation and rejection of monovalent (Na⁺) and divalent (Cu²⁺) ions were studied. In case of polystyrene inner coated MnO₂, the flux increased by 48% compared to TFC membrane that may be related to better dispersion of the nanotubes in PA layer and promoting the permeation through the nanotubes. The nanotubes worked as the channels for water movement through the structure of the membrane and the inner coating makes more restriction for the ions and improves the rejection. Furthermore, the addition of the nanoparticles can reduce the concentration of MPD in the reaction zone and thinner polyamide layer can be expected. In case of polydopamine inner surface-coated MnO₂, the flux improved 84% compared to TFN membrane containing unmodified MnO₂ that is linked to the affinity between polydopamine and water molecules which facilitates the penetration of water through the nanotubes.

Graphical abstract

中文翻译：

---

内部功能化的 MnO2 纳米管用于水和废水处理的薄膜纳米复合膜的改性

纳滤膜等膜技术用于水资源处理。在这项研究中，通过水热法制备了MnO ₂纳米管，然后通过一种新颖的方法用不同的聚合物（聚多巴胺和聚苯乙烯）对纳米管的内表面进行功能化，以改变其内径。然后，将纯纳米管和改性纳米管用于合成薄膜纳米复合材料（TFN）膜，并研究了它们对单价（Na ⁺）和二价（Cu ^{2+ ）离子的渗透和截留性能。}_{在聚苯乙烯内涂覆MnO 2}的情况下，与TFC膜相比，通量增加了48％，这可能与纳米管在PA层中更好的分散并促进通过纳米管的渗透有关。纳米管作为水通过膜结构运动的通道，内部涂层对离子产生更多限制并提高截留率。此外，纳米粒子的添加可以降低反应区中MPD的浓度，并且可以预期更薄的聚酰胺层。_{在聚多巴胺内表面涂覆的MnO 2}的情况下，与含有未改性的MnO ₂的TFN膜相比，通量提高了84％，这与聚多巴胺和水分子之间的亲和力有关，这有利于水穿过纳米管。

图形概要