Preliminary exploration of the dye/salt separation performance of 2D and 3D covalent organic frameworks/nylon 6 membranes prepared by layer-by-layer strategy

Covalent organic frameworks (COFs) had been widely studied as high-performance se-paration membrane materials because of their uniform pore size, high porosity and good stability. In this work, 1,3,5-tris(4-aminophenyl)benzene (TAPB) - 1,3,5-triformylphlor-oglucinol (Tp)-12/nylon 6 membrane, a two-dimensional (2D) COFs membrane, and 4-[tris (4-aminophenyl)methyl]aniline (TAPM)-Tp-6/nylon 6 membrane, a three-dimensional (3D) COFs membrane, were prepared by layer-by-layer strategy. During the experiment, these COFs/nylon 6 membranes showed good properties, such as high water permeance (4522 L m-2 h-1 bar-1 for TAPB-Tp-12/nylon 6 membrane, and 4840 L m-2 h-1 bar-1 for TAPM-Tp-6/nylon 6 membrane), excellent dye rejection (methy-lene blue rejection > 99.7 %), low salt rejection (< 3.4 %), good chemical stability and reu-sability, which might be due to the hydrophilicity and electrical properties of these materials and the support of nylon 6 skeleton. Moreover, the possible reasons for these differences between 2D COFs membrane and 3D COFs membrane were analysed by summarizing and comparing the data obtained from these COFs/nylon 6 membranes. Therefore, this work not only provided a universal method for the synthesis of different types of COFs membranes, but also supplied a reference for researchers in the same field to compare the performance of 2D and 3D COFs membranes.(c) 2023 Institution of Chemical Engineers. Published by Elsevier Ltd. All rights reserved.

Automated summary

In this study, 2D and 3D covalent organic frameworks (COFs) membranes were prepared using a layer-by-layer strategy. These COFs/nylon 6 membranes exhibited high water permeance, excellent dye rejection, low salt rejection, and good chemical stability and reusability. The differences between 2D COFs membrane and 3D COFs membrane were analyzed, providing a universal method for the synthesis of different types of COFs membranes and a reference for comparing the performance of 2D and 3D COFs membranes in the same field.