Graphene oxide (GO) has attracted remarkable attention as a potential material in the fabrication of next-generation membranes with high water permeability and efficient purification. Herein, an easy and effective means of modifying GO lamellar with a phytic acid (PhA) molecule as both an inserter and a surface modifier was developed to fabricate high-performance GO-based membranes. As a result, the addition of PhA to the GO membrane enhanced hydrophilicity and enlarged the interlamellar spacing. The optimal GP-10 composite membrane displayed a high average pure water flux of 6.31 L m–2 h–1 bar–1 under an ultralow pressure nanofiltration condition, which was about 18.6 times higher than that of 0.34 L m–2 h–1 bar–1 for pure GO membrane. At the same time, it possessed the ability to reject different charged dye molecules with a rejection rate higher than 99.88%. In addition, the composite membrane also showed good structural stability under different pH conditions. This study not only provides a method to simply design GO-based membranes by introducing multifunctional small molecules but also sheds light on using such GO composite membranes in practical water separation applications.

Membrane separation is a central area of research in chemical engineering because of its important status as the key technology in chemical separation and water treatment processes. Recently, polymeric graphitic carbon nitride (g-C3N4) has emerged as a candidate material for membrane applications because of its appealing physiochemical properties and ease of fabrication. Herein we review the progress of g-C3N4-based membranes, including the peculiarity of two-dimensional (2D) g-C3N4, the tailoring of functionality, and integration into membrane stacks for practical applications in gas separation, water purification, pervaporation, photocatalytic water filtration, oil-in-water separation, and polymer electrolyte membranes. Moreover, possible development directions of g-C3N4-based membranes are discussed along with the current challenges and future perspectives.

Graphene oxide (GO) based membranes are promising for advanced nanofiltration in water treatments but there is a need to improve water flux and membrane stability. Although the interlayer distance of...