Improvement of water filtration performance of graphene oxide membranes on Nylon support by UV-assisted reduction treatment: Control of molecular weight cut-off

Abstract

Graphene oxide (GO) membranes on Nylon support were modified by UV-assisted reduction to control their behavior in the filtration of water containing organic pollutants. Pyridine, phenol, 2-naphthol and disperse blue 3 were used as probe pollutants to determinate the molecular weight cut-off (MWCO) of the membranes prepared. The membranes were prepared with GO loads of 0.04 and 0.06 mg cm−2 and subjected to UV radiation from a Hg lamp (30 W m−2) for 30–60 min. The non-irradiated membranes showed MWCO ca. 300 Da, with rejection values above 90 % for disperse blue 3, while rejection for 2-naphtol reached 64 %. Irradiation resulted in substantial removal of oxygen surface groups, leading to staking of GO sheets and a decrease of interlayer space. These structural changes narrowed the size of pores thus reducing solutes passage. Rejection of 2-naphtol reached 83 %, i.e. decreasing MWCO to ca. 150 Da. The increase in the rejection of solutes was higher for membranes with a GO load of 0.06 mg cm−2, however similar water permeability was achieved regardless the GO load. UV-reduction shows a high potential for controlling the rejection of solutes by GO membranes on Nylon support while maintaining good permeability.