Preparation of Graphene Oxide Embedded Reverse Osmosis Membrane for High Permeability

Although Reverse osmosis (RO) process has attracted considerable attention as a commercial desalination process, diverse approaches have been studied to increase water production, still maintaining high salt rejection in RO.

In this research, we tried to enhance permeability of RO membrane by introducing superhydrophilic graphene oxide in polyamide layer which was prepared by interfacial polymerization using m-phenylene diamine and trimesoyl chloride. The addition of graphene oxide increased substantially the water permeability of RO membrane. The enhancement of water flux was attributed to the increase of membrane hydrophilicity with the addition of graphene oxide, which was confirmed  by the change in contact angle.

Moreover, the enhancement of water permeability was achieved at a much less amount of graphene oxide addition than other hydrophilic additives reported in other studies. For example, 0.03 wt% zeolite or 3.0 wt% hydrophilized ordered mesoporous carbon (a kind of oxidized carbon nanotube) of total polymer solution weight was reported to enhance the water permeability by around 20%. In contrast, only 0.00005 wt% graphene oxide was required to achieve the same 20% increase with the graphene oxide.

Furthermore, the additive of graphene oxide did not result in the decrease of salt (sodium chloride) rejection, which has been usually reported with other additives. The fact that the addition of graphene oxide did not affect the salt rejection suggests that the water permeability enhancement was not caused by defect made by this additive. The tiny amount, small size as well as thorough dispersion of graphene oxide might prohibit defect formation in the new RO  membrane.

References:
1. Byeong-Heon Jeong, et al., interfacial polymerization of thin film nanocomposites a new concept for reverse osmosis membranes, Journal of Membrane Science, 2007
2. Eun-Sik Kim, et al., Fabrication of polyamide thin-film nano-composite (PA-TFN) membrane with hydrophilized ordered mesoporous carbon (H-OMC) for water purifications, Journal of Membrane Science, 2011