Ion-Selective Separation Using MXene-Based Membranes: A Review

High Resolution Image Download MS PowerPoint Slide Global lack of clean water makes it essential that new technologies are developed for separation of pollutants from raw water. Membrane separation has arisen as a promising solution among other conventional liquid-separation processes, such as evaporation, distillation, and crystallization. Synthetic polymer membranes have been emphasized as an important component in liquid separation processes due to their outstanding water/salt selectivity and ionic conductivity. However, their inherent trade-off between selectivity and permeability has remained a challenge for polymeric membranes. Recently, two-dimensional nanomaterials have been actively sought after as an alternative to polymeric membranes. MXene, a new type of nanomaterial, has been attracting considerable attention as a building block for nanostructured separation membranes. Due to several appealing features, such as their surface functional groups with negative charge, they have been used in size-, charge-, and adsorption-selective separation for different ions or molecules. This article reviews recent progress in MXene-based membranes, with a particular emphasis on ion-selective separation and their applications for water purification including salt rejection, reverse electrodialysis, or heavy metal adsorption. Lastly, the challenges and future directions of MXene-based ion-selective membranes are discussed.