Polyelectrolyte functionalized lamellar graphene oxide membranes on polypropylene support for organic solvent nanofiltration

We have reported, for the first time, a straightforward and eco-friendly approach to molecularly design graphene oxide (GO) nanosheets on robust hydrophobic polypropylene (PP) supports with excellent adhesion and superior separation performance for organic solvent nanofiltration (OSN) of dye/ethanol mixtures. The approach consists of (1) grafting the PP surface with polyethylene glycol (PEG) with the aid of argon plasma (TPP), (2) a pressure-assisted filtration of GO dispersion and (3) functionalization by various polyelectrolytes. We find that the TPP/GO membrane modified by hyperbranched polyethylenimine (HPEI) on its outmost layer has high rejections toward cationic dyes. It has a rejection of 95% toward Alcian blue with a high permeance of 14.9 L m(-2) h(-1) bar(-1). Similarly, it exhibits excellent anionic dye/ethanol separation if it is modified by poly(styrenesulfonate) (PSS) on its outmost layer. It shows a rejection up to 97% toward Rose bengal with a total permeance of 3.1 L m(-2) h(-1) bar(-1). Experimental results confirm that both molecular sieving and electrostatic repulsion play critical factors for GO based membranes to separate dye/organic solvent mixtures. This work may not only widen the selection of membrane support materials for GO deposition but also provide useful insights for developing GO based membranes for OSN. (C) 2017 Elsevier Ltd. All rights reserved.