Graphene quantum dots enhanced ultrathin nanofilms and arginine engineered nanofiltration membranes with ultra-high separation performance

A noticeable improvement of nanofiltration (NF) membranes with high separation performance for desalination was reported in this work. Graphene quantum dots (GQDs) enhanced polyamide (PA) composite membranes (GPA) were composed of porous substrates and nanofilms The nanofilms as separation layers were fabricated by the support-free interfacial polymerization and possessed ultrathin thickness below 8.0 nm. GQDs-PA interface channels and GQDs-GQDs interface channels gradually generated and penetrated the PA functional layer, resulting in a dramatic permeance increase of GPA membranes. The GPA membranes were creatively modified with arginine (Arg) to improve hydrophilicity and narrow the water channels. The Arg-GPA NF membranes under optimized preparation exhibited exceedingly high permeance of 40.3 L m −2  h −1  bar −1 with Na 2 SO 4 rejection rate of 99.7 %, and 60.7 L m −2  h −1  bar −1 with Na 2 SO 4 rejection rate of 99.4 %. This synergistic strategy of GQDs regulation on PA nanofilm structure and Arg post-treatment modification may provide a reliable and efficient technique for the design of NF membranes.