Fabrication And Studiesof Multi-Functional Oil/Water Separation Materials With Special Wettability

Oil/water separation materials and technologies have significantly affected numerous fields including social production,human beings' living and ecological environment etc.Due to increasingly discharge of oily sewage and frequent oil spill accidents caused by industrial production and daily life,as well as the higher requirements to purify and impurity content of the using oils proposed from all make oil/water separation materials important and urgent.Oil/water separation is an issue of interfacial science.Fabrication of oil/water separation materials based on superwetting substances has become the focus of research.Superwetting materials have overcomed the limitations of conventional materials and methods such as low separation efficiency,high cost,and poor selectivity and so on,and greatly promoted the development of oil/water separation.In this thesis,facing these complex and diverse systems of oil and water mixtures,we devoted to developing multifunctional oil/water separation materials and proposed effective solutions to the existing problems containing environmentally friendly way,external-stimuli controllable separation processing and emulsion separation via rational combination of superwetting properties and materials with micro/nanoscale composite architectures,which open up the potential applications of superwetting materials in industry and daily life,at the same time,provide a solid foundation for industrialization of scientific theories.The main contents are as follows,1)An “oil-removing” oil/water separation mesh with rapid separation speed,good selectivity,high reproducibility?more than 30 times?and intrusion pressure of water?about 2.2 k Pa?has been developed by combining mussel-inspired chemistry and Michael addition reaction,which can be used to separate a series of oil/water mixtures.This method,without using any fluoro-polymers,makes the preparation techniques of the “oil-removing” oil/water separation materials less complicated.By integration of mussel-inspired chemistry into the field of oil/water separation,the polydopamine coated surfaces with high active reaction sites as a platform for secondary reaction make it possible for other functional molecules with hydrophilic and responsive groups to be introduced into the surfaces.2)Thermo and pH dual-responsive PDMAEMA hydrogel composite mesh is successfully fabricated by photo initiated free radical polymerization method.The as-prepared mesh achieves in-situ temperature controllable oil/water separation and makes water phase and oil phase permeate through the mesh orderly and be collected separately.Additionally,in-situ p H controllable oil/water separation has been obtained through further interacting with stearic acid via electrostatic self-assemble interaction.These materials have excellent potential to be used in smart controllable separation applications.3)A novel membrane for separation of highly stabilized water-in-oil emulsions has been developed by combining mussel-inspired chemistry and St???ber method.Through integration of functional Si O2 NPs demulsifiers with superwetting mesh substrate,the as-prepared membrane is capable of demulsifying and separating various types of surfactant stabilized water-in-oil emulsions composed by a range of oils such as chloroform,toluene,gasoline and diesel.Besides,the membrane is thermally stable,producible in large-scale and easily stored.4)A facile membrane for separation of highly stabilized oil-in-water emulsions has been reported by one-step immersion method.The influences of special wettability and pore size effect on the emulsion separation performance have been explored via functionalizing hydrophilic polyethylenepolyamine and dopamine hydrochloride onto the mixed cellulose ester microfiltration membrane surface,which realize the capacity of demulsification with high selectivity?separation efficiency,99.6%?and permeation flux(about 30000 Lm^-2h^-1bar^-1)at the same time.The as-prepared materials present underwater superoleophobicity and ultralow oil adhesion properties.During the separation process,the underwater superoleophobic interface with low affinity for oil droplets prevents the coated membrane from adhering and fouling by oils,which makes the recycling of materials easy.