An Amino-modified Zinc Oxide Nanoparticles And Graphene Oxide Composite Membrane For Oil-water Separation

Due to its unique two-dimensional structure and easily controlled physical and chemical properties,graphene oxide has become a new building block of membrane materials.Different from the traditional two-dimensional membrane,graphene oxide-based membrane is formed by the stacking of graphene oxide nanosheets,and fluidic channels with excellent selectivity are formed between the nanosheets.The distinctive layered structure provides fast transport passages for water molecules and prevents other larger molecules from passing through,which has great potential in the separation field.In this paper,a graphene oxide-based membrane supported by filter paper was successfully prepared using vacuum filtration-assisted assembly method with amino modified zinc oxide nanoparticles as crosslinking agent.The application of membrane for oil-water emulsion separation was studied.In the first chapter,a brief summary was given about the origin,hazard,types and traditional treatment methods of oily water.With a general overview to the basic characteristic and the development of membrane separation technology,its applications in analytical determinations environmental protection,biochemical pharmaceutical and other fields were reviewed.The next part introduced in detail the structure and properties of graphene oxide,preparation methods of graphene oxide-based membrane,and its application progress for separation field.In the second chapter,a novel graphene oxide-based separation membrane was prepared.With the coupling agent of nano-zinc oxide particles modified with amino silane(m-ZnO)and the graphene oxide(GO)as raw material,the filter paper supporting graphene oxide-based membrane(GOZ)was successfully prepared through the vacuum filtration-assisted assembly method.The obtained materials were characterized by SEM,XRD,TEM,and FT-IR.The results showed that the layered stacked membrane was formed by covalent cross-linking of m-ZnO with adjacent graphene oxide nanosheets.m-ZnO nanoparticles on the graphene oxide nanosheets increased the wrinkle extent of the membrane surface,which could prevent water from adhering to the sheet surface and promote the flowing of water molecules.On the other hand,the spacing between graphene oxide sheets increased obviously by adjusting two-dimensional transmission channels with the nanoparticles and pure water flux was five times as much as the original.In the third chapter,the separation of oil/water emulsions was carried out by using prepared graphene oxide-based membrane.Under the dead-end filtration mode,Tween 80 stabilized hexane/water,toluene/water and iso-octane/water emulsions were separated by using GOZ membranes.The separation behavior was characterized by a stereo microscope and a UV-vis absorption spectrometer.The permeability of emulsions with different oil types and different oil content was investigated.The results confirmed that the GOZ membrane had excellent separation performance and high permeation flux for the above three emulsions.The permeation flux of surfactant stabilized toluene-water,iso-octane-water and hexane-water emulsion was 1612±230 Lm-2 h-1,1568±140L m-2 h-1 and 1807±187 L m-2 h-1.The filtrate obtained after 10 cycles of separation was still clear and transparent,and flux of the emulsion remained at more than 80%of the initial permeation flux,which indicates that the GOZ membrane has good stability for the separation of oil-water emulsion.In the fourth chapter,the present work was summarized.The application prospects of the graphene oxide-based membrane in the separation field was discussed.