Advances in the application of graphene oxide composite loose nanofiltration membranes for dye and salt separation

The wide application of loose nanofiltration (LNF) membranes in textile wastewater treatment has demonstrated the advantages of efficient separation of dyes and salts. Among them, the composite loose nanofiltration membranes prepared using graphene oxide (GO) showed more efficient dye retention and salt permeability due to its broad specific surface area and abundant oxygenated surface functional groups. In this paper, the four aspects of preparation method, separation mechanism, separation performance and application are described. In terms of preparation methods, this paper focuses on two main methods, phase transformation and interfacial polymerization. In addition, other preparation methods such as mussel-inspired deposition, co-deposition and self-assembly are also discussed. In terms of the separation mechanism, spatial repulsion and electrostatic effect are analyzed as the main mechanisms for the separation of dyes and salts by loose nanofiltration membranes. Moreover, this paper emphasizes the excellent contamination resistance, antimicrobial properties and long-term stability of GO composite loose nanofiltration membranes. In response to these properties, the advantages of the membrane in terms of separation performance are analyzed. Finally, this paper also presents the possible future challenges that loose nanofiltration membranes may face in a wide range of applications.