Bio-inspired molecular bridge anchoring GO laminates onto PAN substrate for molecular separation

Graphene oxide (GO) films are highlighted to have great potential in water purification. The highly chemical and thermally stable polyacrylonitrile (PAN) competently constructs a superior substrate supporting the ultrathin GO laminates under various aqueous environments. However, the lack of available functional groups of PAN substrate, which inevitably leads to an undesirable water-induced peeling of the stacked GO laminates, greatly limits its practical application in constructing a stable GO composite membrane. A hydrolysis-condensation-induced bridge strategy is reported in which a bio-inspired molecular bridge generates a strong adhesion of PAN substrate to GO laminate, meanwhile interlaminar molecular bridges also form to generate a robust GO laminate with excellent resistance to swelling. Such GO composite membranes exhibit structural durability in the treatment of dye-containing wastewater for several days or even longer. The interfacial molecular bridge has little effect on the size-sieving and unique transport capability of the GO laminates. Comparable water permeability with the pristine GO laminates and nearly complete rejection to dyes (i.e. Congo red, methylene blue, and methyl orange) were obtained. The combination of easy fabrication, robust stability, and high performance make the PAN-supported GO membranes advantageous for practical application in textile wastewater purification.