水被称为“生命之源”，是人类社会赖以生存和生态系统运转不可或缺的物质。虽然水是一种可再生资源，但它不是取之不尽用之不竭的。随着人口增长、经济发展、气候变化、科技变革，水资源正面临严重威胁，水资源短缺是未来不可避免的问题。污水净化和海水淡化处理技术的发展一直处于白热化阶段。

Water is called the “source of life” and is indispensable for the survival of human society and the functioning of ecosystems. Although water is a renewable resource, it is not inexhaustible. With population growth, economic development, climate change and technological changes, water resources are facing serious threats and water shortage is an inevitable problem in the future. The development of wastewater purification and desalination treatment technology has been a hot topic currently.

在众多净化工艺中，膜分离技术具有稳定、安全、连续循环等优点。它在克服水资源短缺和水污染的斗争中发挥着至关重要的作用。石墨烯膜因其新颖的结构和快速的水运输而受到青睐。同时，由于其自身的稳定性和分散问题，以及固有的不透水和狭窄的层空间，它已成为膜改性领域的重点选择对象。

Among many purification processes, membrane separation technology has the advantages of stability, safety and sustainability. It plays a crucial role in the fight to overcome water scarcity and water pollution. Graphene membranes are favored for their novel structure and fast water transport. At the same time, it has become a key choice in the field of membrane modification due to its own stability and dispersion as well as its inherent impermeability and narrow layer space.

GSMs在水处理中的应用

Application of GSMs in water treatment

(1)去除重金属离子

重金属大多以阳离子形式存在于水中，如Cu²⁺、Hg²⁺、Ag²⁺、Cd²⁺、Pb²⁺、Zn²⁺、Ni²⁺等，但也有少量以阴离子形式存在，如Cr常以CrO₄^2-和Cr₂O₇^2-的形式存在。通常，膜的过滤能力主要是通过尺寸排除和Donnan排除分离机制的结合来实现的，重金属离子也是如此。除了尺寸筛选外，还利用表面电荷特性和表面极性使膜材料与目标分离之间的力不同，从而实现选择性分离。

(1) Removal of heavy metal ions

Heavy metals mostly exist in water in the form of cations, such as Cu²⁺, Hg²⁺, Ag²⁺, Cd²⁺, Pb²⁺, Zn²⁺, Ni²⁺, etc., but a small amount of metals exist in the form of anions, such as the CrO₄^2- and Cr₂O₇^2- of Cr. Usually, the filtration capacity of membranes is mainly achieved by a combination of size exclusion and Donnan exclusion separation mechanisms, so do heavy metal ions. In addition to size exclusion, surface charge properties and surface polarity are used to enable selective separation by varying the forces between the membrane material and the target separation.

(2)去除有机化合物

石墨烯分离膜用于有机处理时，其表面缺陷和纳米片间隙可为水分子提供运输通道，通过尺寸筛选将其分离。膜表面的亲水性不仅能加速水分子的传输，还能有效防止有机物在膜表面的聚集，从而增强膜的耐污性。

(2) Removal of organic compounds

When graphene separation membranes are used for organic treatment, their surface defects and nanosheet gaps can provide transport channels for water molecules to be separated by size screening. The hydrophilicity of the membrane surface not only accelerates the transport of water molecules, but also effectively prevents the aggregation of organic compounds on the membrane surface, thus enhancing the fouling resistance of the membrane.

(3)海水淡化

海水淡化是解决水资源短缺的重要手段之一。基于过滤筛分和常规蒸馏的新型膜分离技术可以在高膜通量的情况下实现海水淡化的高回收率。石墨烯薄膜具有良好的物理化学性能，如良好的机械强度、热稳定性和化学稳定性、疏水性和相对较薄的原子厚度，已被证明其在水净化过程中效果明显。

(3) Desalination of seawater

Desalination is one of the important means to solve water shortage. The new membrane separation technology based on filtration and sieving and conventional distillation can achieve high recovery rate of seawater desalination with high membrane flux. Graphene films with good physicochemical properties such as good mechanical strength, thermal and chemical stability, hydrophobicity and relatively thin atomic thickness prove to be effective in water purification processes.

总结与展望

石墨烯独特的二维结构和优异的硬度使其成为理想的膜材料。利用石墨烯纳米材料开发新型膜材料是近年来的研究热点，特别是石墨烯功能化方面的研究。同时，引入纳米材料构建结构框架，可以有效克服渗透性与选择性，提高GSMs的防污性能和化学稳定性，具有良好的应用前景。

Summary and outlook

The unique two-dimensional structure and excellent hardness of graphene make it an ideal membrane material. The development of new membrane materials using graphene nanomaterials has been a hot research topic in recent years, especially in the functionalization of graphene. Meanwhile, the introduction of nanomaterials to build structural frameworks can effectively overcome permeability and selectivity, improve the antifouling performance and chemical stability of GSMs, and have good application prospects.

尽管GSMs取得了很大的进展，但仍存在一些新的挑战和机遇。需要在化学改性和添加新的填料方面作出更多的努力。设计和开发与石墨烯膜体系相容性良好的复合材料，可以有效优化膜的结构和性能，确保在GSMs中均匀分散，同时提高特定组分的迁移或选择性分离。其次，大规模制备稳定、均匀的GSMs是实现其工业化应用的关键步骤。要从综合策略入手，避免制备过程中的不足。

Despite the great progress achieved by GSMs, there are still some new challenges. More efforts are needed in chemical modification and addition of new fillers. The design and development of composites with good compatibility with graphene membrane systems can effectively optimize the structure and properties of the membranes and ensure uniform dispersion in GSMs while improving the migration or selective separation of specific components. Besides, large-scale preparation of stable and homogeneous GSMs is a key step toward their industrial application. It is important to start with a comprehensive strategy to avoid deficiencies in the preparation process.