(401af) Polyelectrolyte Modified Graphene Oxide/Polypropylene Composite Membranes for Organic Solvent Nanofiltration

Polyelectrolyte Modified Graphene Oxide/Polypropylene Composite
Membranes for Organic Solvent Nanofiltration

Dan Hua and Tai-Shung Chung^∗

Department of Chemical &
Biomolecular Engineering, National University of Singapore, Singapore 117585,
Singapore

* Corresponding author. Tel.: (+65) 6516 6645; fax: (+65)
6779 1936.

E-mail address:
chencts@nus.edu.sg (T. S. Chung).

Abstract:

In
this work, we have molecularly designed graphene
oxide (GO)
/polypropylene (PP) composite membranes by three steps: (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. The fabricated polyelectrolyte modified GO/PP
composite membranes not only show excellent
adhesion between the GO layer and PP support, but also  exhibit satisfying separation
performance for organic
solvent nanofiltration (OSN) of dye/ethanol mixtures. It is interesting to find that the
TPP/GO membrane with hyperbranched polyethylenimine (HPEI) modified 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 with poly(styrenesulfonate)
(PSS) modified 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 indicate that both molecular sieving and electrostatic repulsion are critical
factors for GO based membranes to separate dye/organic solvent mixtures. This
work may both widen the selection of membrane support materials for GO
deposition and provide useful insights for developing GO based membranes for OSN.

Acknowledgements

The authors are grateful to National Research Foundation,
Prime Minister¡¯s Office, Singapore for funding this research under its
Competitive Research Program for the project entitled, ¡°Development of solvent
resistant nanofiltration membranes for sustainable pharmaceutical and
petrochemical manufacture¡±; (CRP Award NO. NRF-CRP14-2014-01 (NUS grant number:
R-279-000-466-281)). Special thanks are due to Dr. Gui Min Shi, Ms. Yu Zhang, Miss Anastasia Frances
Frederica and Miss Jie Gao for their valuable
suggestions and help.