Graphene-based Composite Membrane Separation—the Study Of The Construction Of Catalytic Materials And Their Removal Of Pollutants In Water

Water is an important resource for humanity.In recent years,water shortage and pollution have become major environmental issues raising extensive concerns from the society.Development of novel functional materials with low energy consumption and sustainable performance become a research hotspot in the environmental field and an urgent need for social development.Graphene-based materials possess very high research value and application potential in the field of water purification.How to develop graphene-based materials with stable structure and good performance is a key scientific problem that graphene-based materials need to solve in water treatment applications.This paper studied the preparation of graphene oxide-based hydrogel membranes?GOHMs?,cross-linking with ferrous ions,structural regulation,and separation of pollutants in water through membranes;Furthermore,nitrogen-doped graphene?NG?and Co₃O₄ were integrated into a membrane device to activate PMS to degrade ibuprofen.The main research contents and results of this article are as follows:?1?In this work,three-dimensional graphene oxide hydrogel membranes?GOHMs?are fabricated by gelation of GO with ferrous ions via vacuum filtration.The ferrous ions serve as cross-linkers to increase the bonding strength between GO nanosheets and to induce microstructure transformation of GO via cation–?interactions to form a 3D lamellar porous structure.Compared with the pure GO membrane,GOHMs not only display high stability in water but also show considerably improved water permeability(111.5 L m^-2h^-1 bar^-1)and retention performance?>99%?for methylene blue?MB?,because the hydrogel structure impressively enhances the connectivity of nanopores as well as the adsorption capacity.In addition,the nanostructures of GOHMs can be controlled by adjusting the amounts of GO or ferrous ions.The water permeation and MB retention reveal the structure changes of different GOHMs,which are consistent with the observations from scanning electron microscopy?SEM?and X-ray diffraction?XRD?.Besides,GOHMs exhibit high permeation and separation performances in a wide p H range.The GOHMs demonstrate a promising technique for practical wastewater purification.?2?Co₃O₄/NG composite catalyst was prepared by integrating nitrogen-doped graphene with Co₃O₄ through a one-step hydrothermal method.Compared with nitrogen-doped graphene,the catalytic performance of Co₃O₄/NG has been greatly improved.Under optimized catalytic conditions,the catalyst is supported on the base membrane,and the ibuprofen solution is catalyzed and degraded by filtration through the membrane treatment device.The catalyst shows excellent stability and cycling performance.