Tuning the oxidation level of GO to construct high performance crosslinked lamellar graphene oxide membrane for pervaporation desalination

Lamellar graphene oxide (GO) membranes have received significant attention in desalination and water treatment due to their unimpeded permeation of water. Intercalation cross-linking is an effective way of improving the stability and perm-selectivity of GO membranes. This work reports a novel strategy to tune the nanostructure and morphology of GO membrane by combining highly oxidized GO nanosheets with borate cross-linking for desalination by pervaporation. The cross-linking processes covalent bonding of hydroxyl groups of GO membrane with sodium borate as the cross-linker, leading to formation of selective and stable three-dimensional GO-borate framework. The enrichment of hydroxyl groups on GO arising from high oxidation benefits the targeted cross-linking. Meanwhile, higher oxidation level of GO leads to higher content of carboxyl groups and improves the hydrophilicity of membrane. Consequently, the borate cross-linked GO membrane fabricated with fully oxidized GO simultaneously exhibits high water flux and enhanced structural stability. The results reveal that the interlayer spacing and swelling behavior of GO membranes are heavily influenced by the oxidation level and cross-linking, which are critical factors affecting the performance of the membranes in pervaporation desalination applications. The findings hold promise for the development of high-performance and stable GO membranes to address global water scarcity challenges.