Graphene Oxide Nanofiltration Membrane Based on Three-Dimensional Size-Controllable Metal–Organic Frameworks for Water Treatment

Abstract

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.