Biomimetic Sustainable Graphene Ultrafast-Selective\nNanofiltration Membranes

Abstract

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