Synergistic effect of one-dimensional silk nanofiber and two-dimensional graphene oxide composite membrane for enhanced water purification

Bombyx Mori silk-derived silk nanofiber (SNF; one dimensional, 1D) is assembled in the active functional group on the surface of graphene oxide (GO; two dimensional, 2D) composite membranes with an average thickness of 36–72 nm. The possibility of large-scale production through a simple chemical synthesis method with solutions of different pH levels of the SNF can be advantageous. The SNF/GOx composite membranes having a combination of 1D nanofiber and 2D materials possess a synthetic effect in the effective rejection rate of salt and dye. Investigation of the physicochemical properties of the SNF/GO composite membrane revealed that SNF interlaces the cavity I4 formed among the GO sheets to promote water flux. The hydrogen bonding interface between SNF and GO forms a specific water channel I3 to ensure the selectivity of Na2SO4 salt rejection. The 1D/2D synergy reveals a flux value of 43 LMH and a rejection value of 95% (up to 1000 ppm at 1.0 MPa pressure). The SNF/GO composite membrane exhibits good stability and increased operating pressure with increasing flux rate and constant rejection values. In addition, the SNF/GO5 wt% composite membrane exhibits excellent dye removal of up to 97%. The results demonstrate the potential of the SNF/GO5 wt% composite membrane to be used for water treatment in practical applications. © 2020 Elsevier B.V.