Separation performance of graphene oxide nanofiltration membrane intercalated by MWCNTs and α -Fe₂O₃ nanoparticles

Nanofiltration (NF) technology is used in the field of water treatment due to its advantages of low energy consumption, high efficiency, and simple process flow. However, the problems of membrane fouling and trade-off (i.e., high flux with low rejection or high rejection with low flux) exist in NF technology, which limit its wide-scale popularization and application. The emphasis of this work is to improve the performance of graphene oxide (GO)-based NF membranes. Multi-walled carbon nanotubes (MWCNTs) and α-Fe₂O₃ were selected to modify the GO-based membrane by expanding the interlayer spacing and enhancing its antifouling and rejection abilities. Our composite membranes exhibit an increased interlayer spacing of 0.787 nm to 1.1 nm, achieving a high pure water permeation flux of 138.96 Lm^-2 h^-1, as well as satisfactory rejection rates for salts and dyes (Na₂SO₄, NaCl, MgCl₂, Congo red, and methylene blue). Additionally, the membranes exhibit a relatively good antifouling property. After five cycles of rejection tests, the flux and rejection rate could be recovered to 90 % from 80 % with a 4-h irradiation under visible light. This study provides valuable insights into the development of high-efficiency and advanced NF membranes.