| The massive discharge of oily wastewater and frequent oil leakage in modern industries have caused serious oil pollution,which caused huge damage to water resources and the environment.Therefore,how to solve oil pollution is a problem that humans must pay attention to.Compared with traditional oil-water separation methods,the method of oil-water separation using super-wetting materials can separate oil-water mixtures quickly,with low energy and high efficiency,and has gradually become a hot spot in oil-water separation research.In this thesis,the stainless steel mesh(SSM)with large pore size,high strength,pollution-free and economical availability was used as the substrate,and a superhydrophilic stainless steel mesh was prepared by a simple in-situ growth method.On this basis,a single high-hydrophobic/superhydrophilic Janus stainless steel mesh(Janus-SSM)was prepared by the surface deposition method,which could be used to separate immiscible oil-water mixtures.Furthermore,the superhydrophilic stainless steel mesh and Janus-SSM were assembled to form a three-dimensional Janus stainless steel mesh layer,and the efficient separation of the emulsified oil-water mixture was realized.The research contents of this paper are as follows:(1)First,a superhydrophilic stainless steel mesh was successfully prepared by in-situ growth of dopamine and silica particles on the stainless steel mesh.The superhydrophilic stainless steel mesh had a water contact angle of 0°,and underwater contact angles of oils(n-hexane,n-pentane,petroleum ether,and isooctane)were higher than 150°,showing good underwater oleophobicity.The superhydrophilic stainless steel mesh could be used to separate the mixture of light oil and water,the oil-water separation efficiency reached 99.80%,the separation flux reached 45000 L·m-2·h-1.The separation efficiency could still maintain at a high level after 20 separation cycles,showing excellent oil-water separation performance.After treatment with strong acid,strong alkali,high concentration salt solution,organic solvent and sand impact,it could still maintain good wetting performance and separation efficiency,showing excellent chemical and mechanical stability.(2)The obtained superhydrophilic stainless steel mesh was grafted with perfluorosiloxane on one side on the phase interface of heavy oil and water to realize single-side hydrophobic modification,and then dopamine was deposited on one side to obtain a superhydrophilic/high-hydrophobic Janus-SSM.The water contact angle of the high-hydrophobic side of the Janus-SSM was 135°,and the water contact angle of the superhydrophilic side was 0°,and the underwater contact angles of n-hexane,n-pentane,petroleum ether,isooctane,dichloromethane and 1,2-dichloroethaneon the superhydrophilic side were all over 150°.Compared with superhydrophilic stainless steel mesh,the Janus-SSM could separate heavy oil/water mixtures and light oil/water mixtures.The separation efficiency was higher than 99.50%,and the separation fluxes were up to 45000 L·m-2·h-1.The Janus-SSM could still maintain high separation efficiency even after 20 separation cycles.After being treated with strong acid,strong alkali,high concentration salt solution,organic solvent and sand impact,the Janus-SSM could still maintain good wetting performance and had excellent chemical and mechanical stability.(3)The obtained single-layer Janus-SSM was combined with multiple pieces of superhydrophilic stainless steel meshes to obtain a three-dimensional Janus stainless steel mesh layer.The three-dimensional Janus layer could not only separate immiscible heavy oil,light oil and water mixtures,but also could achieve efficient demulsification and separation of emulsified oil-water mixtures due to the special three-dimensional channels in the layered structure.The separation efficiency of water-in-oil and oil-in-water emulsions were all greater than 99.30%,and the separation flux could reach up to 7000 L·m-2·h-1. |
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