Fabrication Of Super-wetting Materials And Their Application In Oil-water Separation

The wettability is a very important surface property of the material,which is mainly determined by the structure and chemical composition of the material,and has a great influence on the application.Inspired by the special wettable surfaces with special functions in the nature,such as lotus leaves,roses,and fish skins,people have artificially synthesized special wettable surfaces with special functions and used them in self-cleaning,oil-water separation and other fields.The preparation process of special wettable materials is complicated and the raw materials are expensive,which limits the industrial large-scale production.In this dissertation,waste materials with porous structures existing in nature as raw materials were used to prepare different super-wetting materials by simple methods of spraying and direct use.We explored the stability of super-wetting materials and their potential application value in self-cleaning and oil-water separation.The main researches of this dissertation were shown as follows:(1)The C₃N₄/Bi₂O₂CO₃/CuO(CN/BOC/CuO)composite with catalytic degradation performance of organics under visible light was prepared by hydrothermal method.After modification by polydimethylsiloxane(PDMS),the CN/BOC/CuO composite was deposited on different substrates to prepare a stable superhydrophobic coating with repair properties under visible light.The CN/BOC/CuO coating still maintained superhydrophobicity after being immersed in corrosion solutions of acid,alkali and salt.After being contaminated by sparingly volatile peanut oil,the CN/BOC/CuO coating lost its superhydrophobic properties.CN/BOC heterojunction catalyst can degrade oil or organic solvent contaminants that adhering to the coating surface under the visible light,so the coating recovered its damaged superhydrophobicity after 4 hours of visible light irradiation.The presence of CuO increased the surface roughness,improved the hydrophobicity of the coating surface,and exhibited a self-cleaning effect.(2)The porous solid waste fly ash after being modified by PDMS was sprayed on different substrates to prepare fly ash coatings.Because of the rough structure and the modification of the low surface energy substance,the prepared coating can not only be superhydrophobic in the air,but also superhydrophobic under the oil.PDMS not only acts as a low surface energy modifier,but also acts as a binder to enhance the bonding force between the power and the substrate.A bowl-shaped device made by the fly ash coating can be used to separate stratified oil-water mixtures on demand.In addition,the fly ash coating had excellent chemical stability and can efficiently separate the mixture of acid,alkali,salt and oil.(3)The layer-stacked waste honeycomb cinder(WHC)was prepared by simple soaking,washing,drying,sieving and stacking processes.The WHC had excellent superhydrophilicity under oil.The layer-stacked WHC can be used to remove dyes and tiny water droplets from the dyed surfactant-stabilized water-in-oil emulsion.The volumetric water fraction of the emulsion was 1%.The WHC displayed exceptional separation efficiency and high flux for the emulsion separation,and highly efficient adsorption for various kinds of dyes in water,oil,and emulsion.Interestingly,no tiny water droplets in the filtrate were detected by dynamic light scattering(DLS),even though the concentration of surfactant in the emulsion was up to 2.4 mg/m L.Furthermore,the WHC could remain considerable recyclability after 10 cycles of emulsion separation.The separation efficiency could be improved after the WHC was immersed in corrosive liquid,which showed the excellent chemical durability of the WHC.