NH2-Fe3O4-regulated graphene oxide membranes with well-defined laminar nanochannels for desalination of dye solutions.

Graphene oxide (GO)-based nanofiltration membranes, featuring well-ordered microscopic structure, well-defined 2D nanochannels and superior molecular sieving ability, have attracted sustained research interest in molecular and ionic separation. However, most of current GO laminar membrane have a poor water flux and high rejection of both dyes and salts, which is not suitable for the dye/salt mixture separation. Herein, we report a vacuum filtration strategy to fabricate GO/NH 2 -Fe 3 O 4 nanofiltration membranes with high water flux and excellent separation performance for dye/salts mixture by introducing NH 2 -Fe 3 O 4. The NH 2 -Fe 3 O 4 is not only worked as the rigid spherical nanospacer to tune GO interlayer spacing but also as crosslinkers to improve the stability of GO membrane in water. FTIR, XRD, SEM, zeta potential and contact angle were applied to analyze the chemical composition and morphology of as-prepared membranes. The effect of intercalated NH 2 -Fe 3 O 4 nanoparticles on overall performance of the GO/NH 2 -Fe 3 O 4 membranes was systematically investigated. The resulted membrane with 8 wt% of NH 2 -Fe 3 O 4 loading has high water flux of up to 78 Lm−2 h−1, which is 4.8 times higher than that of pure GO membrane. Moreover, such membrane also displays high congo red rejection (94%) and low NaCl rejection (~15%), rendering the membranes promising for dye/salt mixtures separation. Intercalated NH 2 -Fe 3 O 4 can simultaneously tune the GO interlayer spacing and improve the stability of GO membrane in water. Unlabelled Image • GO/NH 2 -Fe 3 O 4 membranes were prepared for dye/salt mixture separation. • NH 2 -Fe 3 O 4 can simultaneously tune interlayer spacing and improve membrane stability. • GO/NH 2 -Fe 3 O 4 -8 membrane has high water flux and CR rejection but low NaCl rejection. [ABSTRACT FROM AUTHOR]