“Network-Trapped Engineering” To Stabilize Graphene Oxide Membrane Structure for Efficient Salt/Dye Separation

Abstract

Graphene oxide (GO) laminar membranes are considered as ideal candidates for efficient water treatment due to their unique two-dimensional structure and excellent sieving properties. However, the solubility of graphene oxide in aqueous solutions makes it still challenging in practical application. Inspired by the spider web, in this work, we developed a "network-trapped engineering" strategy to stabilize the interlayer spacings of GO membrane for dye wastewater treatment. The sodium alginate (SA) molecular chains chelated by Sr2+ (SA-Sr) was successfully fixed as network and rivets on the GO nanosheets，which subsequently incorporated into the GO laminates. Benefiting from the design of the network structure, the GS-Sr-3.0 membranes exhibited excellent interlayer spacing stability. Meanwhile, this evenly distributed network structure in the GO laminates can further optimize the stacking of nanosheets, forming more orderly 2D confined nanochannels. As a result, the membranes exhibited superior salt/dye sieving performance, with a separation factor up to 179.1 for Na2SO4/CR, while still maintaining an outstanding water permeance of 62.6 L m-2 h-1 bar-1 over 72 h (3 days). Furthermore, the enhanced thermal and mechanical stability of GS-Sr-3.0 membrane was confirmed. Unlike traditional simple cross-linking strategies, this strategy offers a new insight into fine- construction of two-dimensional nanochannels.

Keywords: Graphene oxide membrane, Stabilize, Salt/dye separation, Nanofiltration