Printing ultrathin graphene oxide nanofiltration membranes for water purification

We demonstrated for the first time that inkjet printing can be a low-cost, easy, fast, and scalable method for depositing ultrathin (7.5-60 nm) uniform graphene oxide (GO) nanofiltration membranes on polymeric supports for highly effective water purification. A large area (15 × 15 cm²) GO nanofiltration membrane was printed successfully on a modified polyacrylonitrile (M-PAN) support. Water permeance and rejection of small organic molecules (<1 nm, charged and uncharged) of printed GO membranes can be adjusted by controlling the GO "ink" concentration and/or printing time. Compared with commercial polymeric nanofiltration membranes, printed GO membranes, after optimization, showed approximately one order of magnitude higher water permeance and much higher rejection (>95%) of small organic molecules. Printed GO membranes also showed excellent performance in removing pharmaceutical contaminants, with ∼95% rejection and <10% water permeance decline over extended-period permeation testing. We believe that inkjet printing could be an effective method for preparing ultrathin GO membranes for effective water nanofiltration purification.