Layer-by-layer self-assembly preparation and desalination performance of graphene oxide membrane

Unlike previous utilization of ultrafiltration membranes as supporters of graphene oxide (GO) composite membranes, this study first adopts microporous nylon membranes as substrates. The cationic polyelectrolyte/GO composite membranes are prepared by the layer-by-layer self-assembly method via electrostatic attraction. The introduction of polycations between nanochannels in the GO membranes effectively suppresses the swelling and improves the stability of the membranes. It is found that the polyelectrolytes' charge density and the surface potential of the composite membranes jointly determine the membranes' properties. The experimental results show that the novel GO membranes can obtain high flux and considerable desalination performance under low operating pressure. Typically, the salt rejection rate reaches 66.8% for 1.0 g/L MgSO4, and the flux is 39.8 Lm(-2)h(-1)bar(-1). Benefitting from the GO composite membranes keeping similar retention for both high and low concentration salt solutions, the ideal desalination performance could be obtained through multi-stage processes on the premise of ensuring high flux, which is more suitable for industry.