Fabrication.Structure Regulation Of Graphene-based Adsorbents And Membranes For Pollutants Management

Graphene-based nanosheets(GBNs)are kinds of monolayer two-dimensional nanosheet.Due to its large surface area,specific surface properties,GBNs have arouse great attention in the field of optics,electrics,mechanics,and especially in environmental remediation.GBNs are considered as super adsorbents in water purification.Their excellent performance endow them great potential in environmental remediation.However,as a kind of nanomaterial,direct application in water remediation will inevitabely involve nanoparticle release.Construct GBNs into specific device is a promising way for practical application which not only preserved its pristine properties but also endow it additional seiving performance and also avoid the partile release during application.In view of the interaction between GBNs and pollutants,this study systematically investigated the adsorption-aggregation process and structure transformation of graphene oxide(GO)under the influence of metal ions.This study also constructed SiO2@rGO core-shell structure which make monolayer graphene can stable exsit in water.The super adsorption capacity of monolayer rGO to phenanthrene(PHE)and the interaction between rGO and PHE were investigated.For specific graphene-based membrane construction,ultrathin SiO2 intercalated GO membrane was fabricated which preserved the pristine sieving performanc and increased 2 to 65 times high water flux.Graphene-activated carbon hybrid membrane was constructed which possess both sieving ability and adsorption capacity.Multi-pollutants can be rejected by simple one-step filtrate.Through nanostructure reconstruction,pure activated carbon was first-time realized.With the same sieving performance,the fluc of this novle pure activated carbon membrane was about 25 times higher than common commercial ultrafiltrtion membrane.In conclusion,the main novelty and findings are summarized as the following lists:(1)Studies revealed that heavy metal ions can change GO's surface electronegativity through surface adsorption,beyond EDL suppress.Under the influence of heavy metal ions' surface adsorption,GO nanosheets will transformed into 1D tube-like materials,2D piled structures and 3D spherical structures.(2)SiO2@rGO core-shell structure was fabricated through surface potential regulation which endow monolayer or few-layer rGO can be stable exist in water.Results indicate monolayer/few-layer rGO exhibit excellent adsorption capacity to PHE which was almost 100 times higher than pristine aggregated rGO and also 1000 times higher than the distribution coefficient of hexadecane-water.Through different reduction methods,the surface OCGs containing of rGO was further regulated and the interaction mechanism between rGO and PHE was systematically investigated.According to the abnormal phenomenon,replacement of H-? anchored water by PHE is supposed to the potential interface mechanism during adsorption.(3)SiO2 intercalated ultrathin GO membrane was first-time constructed through surface potential regulation.SiO2 intercalation can well regulate the interlayer structure and maximized the flux of GO membrane under the premise of sieving performance.In addition,SiO2 intercalation can also further regulate the surface roughness,surface hydrophilic-hydrophobic property and surface potential.(4)rGO crosslinked AC membrane was first time fabricated through ?-?interaction and electric repulsion regulation.Because of the full carbon structure,rGO-AC hybrid membrane exhibit strong chemical stability which can stable exist in water,acid or basic solution and corrosive chemical solvents.Through rGO ratio control,membrane pore size can realize facile regulation form micro to nano scale.Hybrid membrane not only preserved the sieving ability of graphene-based membranes but also obtained the strong adsorption capacity of AC.Due to the dual clean mechanisms,this hybrid membrane ran remove multi type pollutants through just one step filtration.(5)Bulk AC was step by step exfoliated through surfactant assistant exfoliation and the inter nanostructure was carefully investigated for the first time.Results indicate bulk AC is constructed by 0 dimensional carbon dots,2 dimensional graphene-like lamella and quantum size carbon dots.Through surface potential and ?-? interaction regulation,these nano carbon structures can be tactfully reconstructed into novel ultrafiltration membrane,without additional cross-linkers.This novel pure AC membrane possess strong chemical stability,narrow sieving pore size,super high water flux and antifouling surface.Excellent properties and performance endow it great potentials in water purification.