Background: The development of new emerging nanomaterials for water treatment has attracted more and more interests recently. MXenes is a generic term for a series of new twodimensional (2D) transition metal carbides and carbonitrides materials which have graphene-like structure. As a new type of 2D lamellar nanomaterial, many researches has focused on the design and synthesis of MXene-based nanomaterials owing to their large number of the inter-layer void with the two-dimensional stacking structure, large specific surface area, rich and adjustable surface functional groups, and strong hydrophilicity. On account of their unique properties, related discussion and potential of 2D MXenes nanomaterials for membrane separation and water treatment applications are provided.

Objective: The goal of this paper is to review new emerging 2D MXenes nanomaterials for the fabrication of various composite membranes and related applications for water treatment.

Methods: In this review, the design and synthesis of MXene-based composite membranes for water treatment was extensively discussed.

Results: Membrane separation technology is an effective approach for solving the water pollution problem due to its low energy consumption, environment-friendly, and easy operation. MXene-based membranes with different molecular sieving behaviors for small organic molecules and ions and corresponding applications in water purification and desalination were discussed.

Conclusion: Although composite membranes constructed by 2D MXenes nanomaterials can be prepared to achieve high water flux and satisfactory rejection, most research focused on the exploration of membrane formation with a multi-layered compound or few-layered MXenes. In the near future, the functional properties of the MXene itself should be paid more attention for the development of various novel membranes.

背景：近年来，用于水处理的新型纳米材料的开发引起了越来越多的关注。MXenes 是一系列具有石墨烯类结构的新型二维 (2D) 过渡金属碳化物和碳氮化物材料的总称。作为一种新型的二维层状纳米材料，MXene 基纳米材料具有大量的层间空隙、二维堆叠结构、比表面积大、丰富且可调等特点，因此许多研究集中在其设计和合成上。表面官能团，亲水性强。由于其独特的性质，提供了 2D MXenes 纳米材料在膜分离和水处理应用中的相关讨论和潜力。

目的：本文的目的是回顾用于制造各种复合膜和相关水处理应用的新兴 2D MXenes 纳米材料。

方法：在这篇综述中，广泛讨论了基于 MXene 的水处理复合膜的设计和合成。

结果：膜分离技术具有能耗低、环境友好、操作简便等优点，是解决水污染问题的有效途径。讨论了对有机小分子和离子具有不同分子筛分行为的基于 MXene 的膜及其在水净化和海水淡化中的相应应用。

结论：虽然可以制备由 2D MXenes 纳米材料构建的复合膜，以实现高水通量和令人满意的截留率，但大多数研究集中在探索多层化合物或少层 MXenes 的膜形成。在不久的将来，MXene 本身的功能特性应该得到更多的关注，以开发各种新型膜。