In the growing area of wastewater reuse, the performance of reverse osmosis (RO) is limited by poor membrane selectivity towards nitrosamines and other low-molecular weight, neutral contaminants. This study aimed to increase RO membrane rejection of N-nitrosodimethylamine (NDMA), a carcinogenic nitrosamine that is produced during chlorination and chloramination of secondary wastewater effluent. Toward this goal, we modified commercial polyamide RO membranes with graphene oxide (GO) nanosheets, and demonstrated that GO functionalization can decrease the NDMA permeability coefficient by 31%, while only decreasing water permeability by 13%. The improved selectivity is likely due to additional steric exclusion derived from the GO nanosheet coating. Moreover, membrane characterization indicated that the GO modification does not change the hydrophilicity or roughness of the interface. The latter interfacial characteristics, combined with the well-established biocidal properties of graphenic nanomaterials, render GO functionalization a promising strategy for the development of highly selective membranes for wastewater reclamation.
Bibliographical noteFunding Information:
This work was supported by grants from the United States Geological Survey ( MN WRC 2015MN362B ), the Environment and Natural Resources Trust Fund , and 3 M Co. (Non-Tenured Faculty Award). Portions of this work were carried out in the Characterization Facility and Minnesota Nano Center, University of Minnesota, which receive partial support from NSF through the MRSEC and NNIN programs, respectively. We thank Dow Water & Energy Solutions for supplying the membrane materials.
- Graphene oxide
- Reverse osmosis
- Wastewater reuse