Study On Preparation And Performance Of GO-Based Membranes

Graphene is a 2D crystals carbon materials in the thickness of one single atom. Its excellent mechanical property, extremely large surface area and ultra-thin molecular thickness make it an outstanding material in the field of separation. As an important derivative of graphene, graphene oxide (GO) not only has excellent hydrophilic, but also easy to design and modify because a large number of oxygen functional groups are at the carbon plate. GO has the unique nanochannel, which is potential for application in desalination, pervaporation and waste treatment. GO-based membranes are not stable, they tend to exfoliate and dissolve in solution. So it is crucial for GO-based membranes to improve their stability so as to realize application in reality.In this paper, we designed and prepared three kinds of chemical crosslinked GO-based membranes and used them in different separation system.(1) Ethylenediamine (EDA)-crosslinked GO membrane:epoxy groups at GO plate reacted with EDA at certain circumstances and produced GO-ED A. GO-EDA nano-layers deposited to membrane by vacuum filtration method. Though optimizing the conditions in preparation process, GO-EDA membrane was synthesis with good stability and separation properties for orange G in dye solution.(2) Multi-walled carbon nanotubes (MWCNTs)-interlinked GO membrane:GO-based membrane has narrow nanochannels between GO layers in solution.In addition, the hydrogen bonds between oxygen functional groups and water molecules hindered the transfer of water molecules. In order to improve the low flux and poor stability, we crosslinked MWCNTs with GO in chemical bond and made MWCNTs-interlinked GO membrane by vacuum filtration. The hybrid membrane was used to concentrate radioactive waste of Sr(NO3)2 in low concentration. As a result, flux of the hybrid membrane achieved 210.7 L/(m2h), which was 4 times of commercial membranes. The hybrid membrane showed high rejection for Sr-EDTA. Besides, it could also be used to separate Na+/Sr2+ mixtures. These results indicate that the MWCNTs-interlinked GO membrane has promising prospects for application in radioactive waste treatment.(3) Modified SWCNTs-interlinked GO membrane:Modified SWCNTs-interlinked GO membrane was prepared by vacuum filtration. The hybrid membrane could operate steadily at cross-flow condition because of the chemical bond. The membrane was applied to the treatment of Sr2+containing waste water. The distance between GO layer was enlarged by crosslinking carbon rod and the flux was increased to 390.6 L/(m2·h), which was 8 times of commercial nanofiltration membranes. After adding EDTA, rejection increased to 86.3%. In addition, the separation mechanism of GO-based membranes was explored by testing the membrane at different pressure and pH, which is of great importance for studying GO-based membranes.To sum up, this paper designed and prepared three structures of GO hybrid membranes by choosing different crosslinking agent and applied them to separate dye and radioactive waste treatment. The distance between GO layers was adjusted and the stability of GO-based membranes were improved as well. It is of significance for GO-based membranes to apply in reality.