(152a) Dye-desalination membranes constructed using amine functionalized holey graphene oxide (HGO)

Membranes with high water permeance, almost zero salt rejection, and ~100% dye rejection are of great interest for dye removal from textile wastewater. Herein, we designed membranes based on amine-functionalized porous graphene oxide (aHGO) for dye desalination. First, GO was etched with hydrogen peroxide to create in-plane nanopores to reduce tortuosity and enhance water and salt permeance while maintaining dye rejection. Second, HGO was functionalized using diamine and triamine to improve its stability, adhesion to the porous support, and separation performance. We thoroughly investigated the effect of amine type and content, and reaction time on the membrane structure and performance, aiming to derive the structure-property relationship. Amine functionalization increases the interlayer spacing of HGO from 0.78 to 0.94 nm and reduces the swelling by water. For example, wetting the HGO/PES membranes increases the d-spacing from 0.78 to 0.90 nm, while wetting the 1dHGO/PES membrane increases the d-spacing from 0.94 to 0.96 nm (for diamine treated HGO). A membrane of ~500-nm aHGO exhibits dye water permeance of >120 LMH/bar, Na2SO4 rejection of ~5%, and Direct red (1372 g/mol) rejection of >99.5%, superior to many GO membranes reported in the literature. Moreover, aHGO membranes show similar dye desalination performance irrespective of the supports (Nylon or PES), showcasing versatile and reproducible characteristics of the membranes.