Fabrication of PEI modified GO/MXene composite membrane and its application in removing metal cations from water

The instability and low permeability of graphene oxide (GO) membranes in water treatment limit their wide application. In this study, we described the fabrication and testing of GO/MXene composite membranes modified by polyethylenimine (PEI). The unique structure of the composite membranes exhibited a synergistic effect in terms of water permeability and metal cation rejection, which varied with the mass ratio of GO and MXene. The composite membranes with a GO/MXene mass ratio of 1: 4 exhibited a higher water permeability (9.5 ± 0.4 L m−2 h−1 bar−1). The PEI modified composite membrane had a rejection of over 70% for Ca2+ and Mg2+, which was about 7 times higher than that of the GO membranes. The removal mechanism of the PEI modified GO/MXene composite membrane on metal ions mainly involved steric effect and electrostatic effect. This kind of modified membrane has great potential in water softening.