A combined experimental and molecular dynamics study revealed the role of oxygen debris (ODs) and functional groups on the nanofiltration performance of a graphene oxide (GO) membrane. A NaOH treatment removed ODs adsorbed onto the graphene oxide (DGO). COOH-decorated GO (CGO) was prepared by controlling the oxidation time of Hummer's method, resulting in 45% of carbons with a COOH group. The water permeance of the prepared GO membrane without ODs was 1 order of magnitude greater than that of GO membranes in our experiments: 1.24, 1.59, and 14.7 L m-2 h-1 bar-1 for GO, CGO, and DGO. However, the rejection of dye molecules below 1 nm in size was dramatically reduced without ODs, indicating that ODs play a critical role in rejecting molecules below 1 nm in size because of electrostatic and hydrogen bonding interactions and by narrowing the effective interlayer spacing, as noted in molecular simulations. Additionally, the CGO membrane displayed a similar separation performance compared to common GO membrane mainly decorated with OH and epoxy.
Bibliographical noteFunding Information:
This research was supported by the Basic Science Research Program through the National Research Foundation of Korea funded by the Ministry of Education (2015R1A6A3A04057367), with further support coming from the Climate Change Research Hub of KAIST (grant no. N01150139).
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Physical and Theoretical Chemistry
- Surfaces, Coatings and Films