Graphene-based woven filter membrane with excellent strength and efficiency for water desalination

TY Liu and JH Lyv and YH Xu and CB Zheng and YS Liu and R Fu and LJ Liang and JY Wu and ZS Zhang, DESALINATION, 533, 115775 (2022).

DOI: 10.1016/j.desal.2022.115775

Nanoporous graphene/graphene oxide (NPGs/NPGOs) has been widely used in desalination because of their high selective separation efficiency. However, it is difficult for NPGs/NPGOs to achieve both high water flux and excellent mechanical properties. In this paper, graphene strips are woven into filter membrane (GWFMs), which can significantly increase mechanical property. Water flux, flow rate, salt rejection and mechanical properties of GWFMs are calculated by molecular dynamics (MD) simulation. Two nanopore size of GWFMs are designed, namely 0.8 nm and 0.6 nm. The tensile strength of GWFM-0.6nm and GWFM-0.8nm are 48.87 GPa and 42.29 GPa, with water flux as high as 18.53 +/- 0.99 L cm(-2) day(-1) MPa-1 and 39.22 +/- 2.50 L cm(-2) day-1 MPa-1, which are three orders of magnitude higher than existing commercial reverse osmosis membranes in water flux. The free energy profiles of H2O and ions passing through GWFMs show that the free energy barrier difference between water molecules and Na+/Cl- can reach similar to 35 kBT (GWFM-0.6nm), guaranteeing almost 100% desalination efficiency at constant pressure from 10 MPa to 500 MPa during simulation time. Our results provide general framework to design desalination membrane with high water flux and high tensile strength using nano-woven technic.

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