Biomimetic Sustainable Graphene Ultrafast-Selective Nanofiltration Membranes

Abstract

In nature, the frog's skin can be permeated by water via collecting water from the humid environment, which is important for its life activities. Inspired by this phenomenon, herein we designed a bioinspired strategy that involved the synergistic effect of lignin and reduced graphene oxide (rGO) layers to achieve fast water transport and excellent organic dyes separation. These nanocomposite membranes exhibited ultrahigh water permeance of 11 820 L m(-2) h(-1) bar(-1) and separation performance of 100% rejection rates, over 300 times higher than traditional GO membranes. In this biomimetic membrane, the hydrophilic lignin enlarged the water nanochannels of the ordered laminates through cross-linking with GO layers, leading to an increased water driving force. Moreover, the lignin chains also provide excellent molecular sieves for the organic dyes across the GO laminates. Finally, the cross-linking lignin chains within the interlayers of laminates can restrict the movement of nanosheets, realizing the good stability of membranes. We believe that this bioinspired method opens an effective avenue for designing and fabricating high-performance nanofiltration 2D membranes for water purification and molecular separation.