Preparation Of Graphene Oxide-based Composite Membranes And Study On Their Dye Separation Properties

Graphene and its derivatives have shown potential applications in seawater desalination and wastewater treatment due to their unique pore structure and ionic molecular sieving ability.Graphene oxide(GO),as one of the most important derivatives of graphene,maintains the unique two-dimensional structure of graphene.GO can be prepared on a large scale and has excellent chemical stability.There are a large number of oxygen-containing functional groups at its surface and edges.This structure endows it with the characteristics of easy membrane formation,large specific surface area,and good hydrophilicity.Membrane separation has attracted the attention of researchers and is widely used in the treatment of dye wastewater.In order to prepare separation membrane with excellent stability,high water flux and good separation performance,novel graphene oxide composite membranes were fabricated by vacuum suction filtration technology,which using graphene oxide and partially reduced graphene oxide as the matrix material composite,titanium dioxide nanoparticles were also doped into the composite membranes to enhance its separation capability.This work mainly includes the following contents:(1)Graphene oxide/reduced graphene oxide composite membranesA highly stable graphene oxide/reduced graphene oxide(GO/rGO)composite membranes was successfully prepared by an in-situ chemical reduction method using a mixed cellulose ester filter membrane with a pore size of 0.22 μm as the base membranes.Using ammonia water as a reducing agent effectively promoted the deoxygenation of the GO surface and the recovery of π conjugation,resulting in rGO with good dispersion.Furthermore,the weakening of hydration and the enhancement of π-π conjugation force promote the increase of the interlayer force of the GO/rGO composite membranes,which makes it exhibit extraordinary stability in strong acid and alkali solutions.In organic dye separation applications,the composite membranes exhibit excellent retention performance with a retention rate of up to 100%.In addition,the GO/rGO composite membranes showed higher water flux(23.72 L m-2 h-1 bar-1)compared to pristine GO membrane(14.35 L m-2 h-1 bar-1)and rGO membrane(8.66 L m-2 h-1 bar-1).This work will expand the application of graphene oxide-based membranes in water treatment.(2)Graphene oxide/reduced graphene oxide/TiO2 composite membranesGraphene oxide,reduced graphene oxide and titanium dioxide nanoparticles(GO/rGO/TiO2)ternary composite membranes were successfully prepared.by vacuum filtration on hybrid cellulose ester filter membrane with a pore size of 0.22 μm.The GO/rGO/TiO2 composite membranes has a layer-by-layer structure,and the TiO2 nanoparticles are uniformly distributed between the layers,which enlarges the mass transfer channel.The water flux of the composite membranes and the rejection rate of organic dyes were tested,the GO/rGO/TiO2 composite membranes showed a water flux value as high as 58.96 L m-2 h-1 bar-1 and 100%rejection of EY,EBT,MB and RhB.The research shows that the GO/rGO/TiO2 composite membranes has good application prospects in wastewater treatment and seawater desalination.