Vacuum-assisted assembly of ZIF-8@GO composite membranes on ceramic tube with enhanced organic solvent nanofiltration performance

Abstract

Organic solvent nanofiltration (OSN) is an emerging technology for molecular separation and purification in organic media. The separation performances are mainly depended on the material and structure of the membrane. In this study, Zeolitic Imidazolate Framework (ZIF-8) nanoparticles were in situ growth onto the surface of graphene oxide (GO) sheets to form ZIF-8@GO composites, which were co-deposited with polyethyleneimine (PEI) matrix on tubular ceramic substrate through a vacuum-assisted assembly method. The dispersion of ZIF-8 nanoparticles in PEI matrix as well as the compactness and uniformity of the composite membranes were readily improved due to the templating effect of lamellar GO sheets and the transmembrane pressure. Membrane performance in OSN was evaluated on the basis of methanol permeance and retention of dye molecules. Methanol permeance increased when ZIF-8@GO laminates were embedded into the PEI layer, whereas the retention remained higher than 99%. The improvement of separation performance may be due to the well dispersion of ZIF-8 nanoparticles in PEI matrix, which offers more well-defined pathways for solvent molecules. Building on these findings, we demonstrate a simple scalable method to obtain robust ZIF-8@GO based membranes with enhanced OSN performance.