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Carbon nanomaterials have proven their wide applicability in molecular separation and water purification techniques. Here, an unzipped carbon nanotubes (CNT) embedded graphene oxide (GO) membrane (uCNTm) is reported. The multiwalled CNTs were longitudinally cut into multilayer graphene oxide nanoribbons by a modified Hummer method. To investigate the varying effects of different bandwidths of unzipped CNTs on their properties, four uCNTms were prepared by a vacuum-assisted filtration process. Unzipped-CNTs with different bandwidths were made by unzipping multiwalled CNTs with outer diameters of 0–10, 10–20, 20–30, and 30–50 nm and named uCNTm-1, uCNTm-2, uCNTm-3, and uCNTm-4, respectively. The uCNTms exhibited good stability in different pH solutions, and the water permeability of the composite membranes showed an increasing trend with the increase of the inserted uCNTm’s bandwidth up to 107 L·m–2·h–1·bar–1, which was more than 10 times greater than that of pure GO membranes. The composite membranes showed decent dye screening performance with the rejection rate of methylene blue and rhodamine B both greater than 99%.

Advanced membrane separation technology plays an important role in achieving excellent water treatment, which can help solve the freshwater crisis. However, there remains a trade-off between membrane permeability and selectivity. An emerging candidate to address this issue is graphene oxide (GO), a two-dimensional (2D) laminated graphene derivative with abundant oxygen functional groups. Furthermore, the transport channels of GO-based membranes can be artificially modified and manipulated, exhibiting great promise for GO in the field of water purification and molecular separation. This review comprehensively summarizes the research advances on 2D GO-based membranes for high-performance nanofiltration (NF). It begins with an elaboration on the preparation methods of GO-based membranes, followed by a detailed summary of the chemical modification and physical manipulation of transport channels. Then we reviewed the current research progress of theoretical calculation and molecular dynamics simulation. Also, the high NF performance of GO-based membranes is presented. Finally, the remaining challenges and future prospects in order to develop advances in membrane technology are provided.

Water pollution has long been a threat to human sustainability, and the development of nanofiltration membrane materials for water treatment is receiving increasing attention. Graphene oxide (GO) nanomaterials have demonstrated their widespread applicability in molecular separation and water purification technologies in recent years. However, the separation performance of the GO membrane (GOM) will decrease with long-term humidity. In this paper, we report a zeolite imidazole framework-8 (ZIF-8) nanoporous material embedded in a GOM, namely, GOZMs. After the positively charged ZIF-8 is compounded with GO, the separation and permeability of the composite nanofiltration membrane significantly improve, and it can remain stable during the long-term permeation process. Besides, four different ZIF-8 sizes were successfully prepared to investigate the effects of different porous particle sizes on composite nanofiltration membranes. The water permeability of the composite nanofiltration membrane increases monotonically with the increase of the ZIF-8 particle size, reaching 136.4 L m–2 h–1 bar–1, which is about 6 times higher than that of the pure GOM. The composite nanofiltration membrane exhibits decent dye screening performance while ensuring high water permeability. The rejection of rhodamine B and methylene blue was close to 100%, and the rejection of methyl orange was consistently lower. Therefore, the successful preparation of GOZMs paves a unique way for designing and developing novel nanofiltration membranes for water treatment and dye separation.

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