2D Material Based Advanced Membranes for Separations in Organic Solvents

Abstract

2D materials have shown high potentials for fabricating next‐generation membranes. To date, extensive studies have focused on the applications of 2D material membranes in gas and aqueous media. Recently, compelling opportunities emerge for 2D material membranes in separation applications in organic solvents because of their unique properties, such as ultrathin mono‐ to few‐layers, outstanding chemical resistance toward organic solvents. Hence, this review aims to provide a timely overview of the current state‐of‐the‐art of 2D material membranes focusing on their applications in organic solvent separations. 2D material membranes fabricated using graphene materials and a few representative nongraphene‐based 2D materials, including covalent organic frameworks and MXenes, are summarized. The key membrane design strategies and their effects on separation performances in organic solvents are also examined. Last, several perspectives are provided in terms of the critical challenges for 2D material membranes, including standardization of membrane performance evaluation, improving understandings of separation mechanisms, managing the trade‐off of permeability and selectivity, issues related to application versatility, long‐term stability, and fabrication scalability. This review will provide a useful guide for researchers in creating novel 2D material membranes for advancing new separation techniques in organic solvents.

Recent Progress on Two-Dimensional Materials

“…Recently, along with the understanding of ultrafast water transport in the 2D capillary (Fig. 59c, d) 1497,1523,1524 , the lamellar membranes made by 2D materials have attracted increasing attention in desalination, reverse osmosis, and nanofiltration 1525,1526 . Numerous chemical modification and cross-linking strategies have been developed to promote the permeation and lifetime of desalination and nanofiltration membranes based on the GO (Fig.…”

Structure Dependent Water Transport in Membranes Based on Two-Dimensional Materials

“…With the surge in clean water demand, extensive technologies have been developed in research as well as on the industrial scale. The introduction of nanomaterials, attributed to the very popular two-dimensional graphene structure, has illuminated enhancement in the properties and conditions required for the membrane applications including water purification and desalination. − Various 2D materials have taken positions as potential candidates for this application, including, graphene-based materials (GO, RGO, functionalized graphene), MXenes, transition metal dichalcogenides (MoS 2 , WS 2 ), organic frameworks (MOFs, COFs), and boron-nitride. In view of this, these state-of-the-art materials have shown tremendous results with high water permeation and excessive salt rejection, at the same time removing some potential barriers occurring in the conventional processes as well as processing materials.…”

Designing organic solvent separation membranes: polymers, porous structures, 2D materials, and their combinations

“…COFs have low density, high crystallinity, large surface area, and good control over pore size and properties by fine-tuning the type of monomers, chemical reaction, and method of preparation. 2,101,[204][205][206] COFs are classified either based on the type of functionalities they contain or by the method of preparation. On the basis of functionality, COFs are classified in 6 types: (a) imine-based, 207,208 (b) boron-based, 209 (c) keto-enamine based, 72,210 (d) triazine-based, 211 (e) urea-based, 212 and (f) C-C bonded.…”

“…299 MXene is another alternative 2D material showing potential application for OSN. 206,300 MXene is transition metal (e.g., Ti and Mo) carbides, nitrides, or carbonitrides (formula, M n+1 X n T x , n=1-4), which can be exploited from the MAX phase using hydrofluoric. 301 For example, double-layered Ti 3 C 2 Tx MXenes membranes showed acetone and acetonitrile permeance as high as 5000 LMH/bar and rejection up to 96% for the dye molecules larger than 2.0 nm, such as reactive black (RB) in isopropanol.…”