Ultrathin water-stable metal-organic framework membranes for ion separation

Abstract

Owing to the rich porosity and uniform pore size, metal-organic frameworks (MOFs) offer substantial advantages over other materials for the precise and fast membrane separation. However, achieving ultrathin water-stable MOF membranes remains a great challenge. Here, we first report the successful exfoliation of two-dimensional (2D) monolayer aluminum tetra-(4-carboxyphenyl) porphyrin framework (termed Al-MOF) nanosheets. Ultrathin water-stable Al-MOF membranes are assembled by using the exfoliated nanosheets as building blocks. While achieving a water flux of up to 2.2 mol m−2 hour−1 bar−1, the obtained 2D Al-MOF laminar membranes exhibit rejection rates of nearly 100% on investigated inorganic ions. The simulation results confirm that intrinsic nanopores of the Al-MOF nanosheets domain the ion/water separation, and the vertically aligned aperture channels are the main transport pathways for water molecules.

Construction of Metal‐Organic Frameworks (MOFs)–Based Membranes and Their Ion Transport Applications

“…Notably, the artificial solid‐state MOF‐based membranes exhibit potential ion transport applications, including energy conversion, ion/molecular separation, biosensing, water desalination, etc. [ 40–45 ]…”

A Review of Nanostructured Ion‐Exchange Membranes

“…Several porous frameworks such as porous aromatic frameworks (PAFs), covalent organic frameworks (COFs), porous organic cages (POCs), hydrogen-bonded organic frameworks (HOFs), and particularly the metal-organic frameworks (MOFs) have been used to fabricate energy-efficient IEMs (Figure 1a). These porous frameworks transform into the membranes by various means, such as the contra-diffusion process, [2,6,7] spin coating method, castings with a doctor blade, vacuum filtration method, electrochemical depositions, [3,8] and secondary growth method. Besides the frameworks-integrated nanostructured IEMs, carbon nanotubes (CNTs) and graphene nanosheets [9] also remained useful to fabricate energyefficient ion-exchange membranes.…”

Supramolecular fabrication of hyperbranched polyethyleneimine toward nanofiltration membrane for efficient wastewater purification

“…[1][2][3][4] Currently, separation membranes have gained increasing attention in various domains, such as removing heavy metals, water desalination, and oily wastewater treatment. [5][6][7][8][9][10][11][12][13][14][15] They have dominant advantages, such as low energy consumption and suitable retention property for pollutions with a 200-1000 Da molecular weight. [16][17][18][19][20] In particular, more attention has been focused on polymeric separation membranes owing to their superiorities, including low cost, environmentally benign, and energy-efficient.…”