Factors affecting the separation performance of graphene oxide membranes: mechanical support, properties of graphene oxide, and exotic species

Abstract

BACKGROUND Graphene oxide (GO) membrane with 2‐dimensional nanocapillaries has gained worldwide attention. To manipulate the membrane separation performance, most existing studies focused on sandwiching appropriate species between GO layers. This study aimed to provide multiple strategies to manipulate the GO membrane separation performance, including the mechanical support, properties of GO nanosheets, and exotic species (i.e. cross‐linkers and residual water molecules). RESULTS Used as the support material, compared with the nitrocellulose membrane, the polyvinylidene fluoride membrane offered stronger mechanical strength to ensure a stable flux. Additional mechanical support could be provided by the non‐woven cloth underneath the GO membrane. The use of GO nanosheets with smaller sizes obtained by centrifugation of the GO suspension increased the water flux and NaCl rejection. Cross‐linking GO layers by Ca2+ resulted in a decreased water flux but increased salt rejection. The same phenomena was observed for the GO membranes post‐treated by vacuum drying, which, compared with air drying, evaporated more residual water molecules from the nanocapillaries. CONCLUSION Results suggested that the mechanical support, properties of GO nanosheets, cross‐linkers, and residual water molecules greatly affected the membrane water flux and rejections, which could be utilized as strategies to manipulate the GO membrane separation performance. © 2017 Society of Chemical Industry

Construction of a highly stable g-C3N4/NH2-MIL-88B(Fe)/CD@graphene oxide self-cleaning membrane for dye wastewater separation and degradation

“…The ideal level of the 2D nanocapillary formed by tightly packed GO nanosheets, and the prominent oxygen-containing functional groups separate adjacent nanosheets to form nanocapillary, which can significantly improve the rejection rate of the membrane. 61 The added g-C 3 N 4 /NH 2 -MIL-88B(Fe)/CD composite photocatalyst and GO separate dye wastewater under electrostatic attraction, π–π* interaction or hydrogen bonding. During the dye retention test, the dye molecules or other organic pollutants will adsorb on the membrane surface or membrane pores and cause membrane fouling, resulting in poor membrane separation performance and shortened membrane service life.…”

Greener organic synthetic methods: Sonochemistry and heterogeneous catalysis promoted multicomponent reactions

“…A notable peculiarity of many of these supports – as is the case with graphene - is the property of having the surface easily modifiable, which is only possible due to the presence of large points of nucleation or stabilization [103] . Other characteristics of these materials that make them remarkable interesting from the point of view of catalysis are porosity, low interaction with supported materials, and good mechanical resistance [105] , [106] , [107] , [108] , [109] . In turn, these mixed catalytic systems still have the benefit of being easily removable from the reaction medium, highlighting them in the search for more sustainable synthetic protocols [110] .…”