Performance improvement strategy for water treatment films: MXene and GO

Abstract

The shortage of water resources will continue to drive the need for technologies for water purification. Membrane separation has become the most commonly used technology for water treatment due to its low environmental impact, high efficiency, low cost and convenient operation. This technology has found widespread applications in various fields such as desalination, the separation of textile wastewater dyes and salts, oil–water separation, removal of heavy metal ions and antibacterial materials. The pores on the surface of the two-dimensional (2D)layered materials and the nano-scale interlayer spacing formed by the stacking of sheets can provide an effective path for the solution to pass through. By adjusting the number and diameter of the surface pores and the interlayer spacing that salt ions and macromolecular etc. are separated from the aqueous solution to meet the needs of industry and life. The graphene oxide (GO) family has been widely used in water treatment for decades due to it's unique layered 2D structure. Since its discovery in 2011, MXene has become the most promising new 2D material after GO in the field of water treatment. Although GO and MXene membranes have occupied important positions in the field of water treatment, some technological challenges still limit their widespread application, including low water flux, low rejection rate, low stability and complicated manufacturing processes. To systematically understand and solve the above problems, this paper compares and analyzes the similarities and differences between the two materials including their structure, preparation methods, membrane performance, water treatment principle and optimization strategies, and applications in water treatment. A variety of commonly used materials preparation methods are summarized, and the performance optimization strategies that can be implemented to solve the current water treatment membrane problems are highlighted. The comparative analysis reveals that the preparation methods for GO are more mature than those of MXene. GO membranes may achieve slightly higher hydrophilicity, but relatively lower water flux. The properties of the membranes can be controlled by chemical and physical modifications, including chemical crosslinking, intercalation, and surface modification to obtain performance improvement for membrane separation. This work will help researchers to choose more suitable materials and preparation methods tailored to specific needs, and it summarizes conditions for the preparation of GO and MXene membranes with wider application range and higher quality.