Graphene oxide nanofiltration membranes for desalination under realistic conditions

The demands of clean water production and wastewater recycling continue to drive nanofiltration membrane development. Graphene oxide (GO) membranes have exhibited the potential to revolutionize nanofiltration, but sustaining high solute rejections at realistic concentrations remains a major challenge. Here we show that a series of membranes based on GO bound to polycyclic π-conjugated cations such as toluidine blue O show substantially enhanced rejections for salts and neutral solutes over a wide concentration range. The observed solute rejection behaviours in these π-intercalated GO membranes can be understood by a dual mechanism of interlayer spacing modulation and creation of diffusion barriers in the two-dimensional interlayer galleries. These membranes are easily scalable and possess good chemical and mechanical robustness in desalination of a multicomponent industrial stream at elevated pH, temperature, stream velocity and solids content. The demands of sustainable energy supply and clean water production continue to drive membrane development. Here the authors design graphene oxide membranes intercalated with polyaromatic cations that not only exhibit sustained nanofiltration performance under realistic conditions but also are scalable for industrial applications.