Ultrafast ionic and molecular sieving through graphene oxide based composite membranes

Graphene oxide (GO) based membranes have been widely explored for water purification and desalination applications, however, it shows less rejection for small ions and molecules, due to lack of pristine graphitic sp(2) domains and smaller interlayer spacing. In this work, we fabricate a unique class of GO based composite (cGO) membranes with large interlayer spacing from GO by serine amino acid (SAA) as a cross-linker and reducing agent using simple strategy. The cGO/SAA membrane (similar to 280 +/- 20 nm) showed an outstanding separation efficiency for several organic dyes with ultrafast permeability i.e. rhodamine B (Rejection 99 +/- 1% and permeance 930 +/- 10 Lm(2)h(-1)bar(-1)), methyl blue (98 +/- 1% and permeance 980 +/- 10 Lm(2)h(-1)bar(-1)) and DI water (1050 +/- 10 Lm(2)h(-1)bar(-1)). In addition, these membranes were also used for the separation of different salts such as NaCl, MgCl2, Ni(NO3)(2) and Pb(NO3)(2) and show good rejection for Pb(NO3)(2) up to 92 +/- 2%. Beside this, these membranes found to be very stable in aqueous environment for -65 days. We believe with the help of this strategy, various 2D materials based membranes can be developed and used in water filtration and desalination.

Automated summary

A class of GO-based composite membranes with large interlayer spacing was fabricated using serine amino acid as a cross-linker and reducing agent, which showed outstanding separation efficiency and high permeance for organic dyes and salts. The membranes exhibited good rejection for various substances and high stability in aqueous environment, indicating their potential application in water filtration and desalination.