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.
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© 2018 American Chemical Society.
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Physical and Theoretical Chemistry
- Surfaces, Coatings and Films