Oil-water Separation And Properties Based On The Composite Materials With Special Wettability

Crude oil exploitation or ocean-going oil tanker oil spills will cause a large amount of crude oil to leak to the surface of the sea or the bottom of the sea,causing damage to the marine system.At the same time,the oily wastewater discharged from textile,metallurgy,food and petrochemical industries will also destroy the natural environment.The use of combustion,bioremediation,centrifugal separation and eucalyptus oil treatment of oily wastewater will have problems of low efficiency and high cost,and cannot be separated the emulsified oily wastewater.Therefore,two products have been developed in this paper,one is a film bag that quickly absorbs the oil phase in the oil-water mixture,and the other is a deposited ZnO non-woven composite film that efficiently separates the emulsion.A membrane bag made of a superhydrophobic/superlipophilic microporous membrane,which was filled with a polyurethane sponge.The superhydrophobic/superlipophilic microporous membrane is prepared by a coarse-phase magnesium plate as a substrate-assisted phase inversion method,and the surface of the membrane is bonded with a micro/nano secondary structure of the roughened magnesium plate.The absorption properties of the film bag were evaluated by the absorption capacity and the absorbed oil purity.The absorption properties of the membrane bag under cyclic absorption,sandpaper scratching and harsh conditions were investigated.Experiments have shown that the membrane bag can absorb oil with a capacity of up to 18-25 times its own weight,and the absorbed oil has a purity of 99.9%.After the film bag absorbs the n-hexane water mixture in 40 cycles,the surface still has a water contact angle of up to 150°and excellent oil storage stability.After scraping the film bag 36 times with 1000#water-resistant sandpaper,the purity of n-hexane absorbed by the film bag can still reach 99.1%.Under harsh conditions such as acid,alkaline,salt water and hot water,the purity of n-hexane absorbed in the membrane bag can still reach 99.1%.A superhydrophilic/underwater superoleophobic composite membrane based on a flexible material nonwoven fabric was prepared.The substrate was hydrophilically modified by UV-grafting polymethacrylic acid,and then nano-particle ZnO was deposited on the surface of the substrate by hydrothermal synthesis.According to the surface microstructure,selecting the concentration of Zn（CH₃COO）₂·2H₂O,the amount of NH₃·H₂O and the reaction time.The changes before and after the filtration of the emulsion were compared by oil droplet size distribution,permeate purity and chemical oxygen demand analysis.The effect of the ZnO non-woven composite membrane circulating filtration emulsion on the permeation flux and the purity of the permeate was discussed.Experiments have shown that the water contact angle of the surface of the hydrophilically modified nonwoven fabric substrate is reduced from 88.2°to 43.4°.Better choice is Zn（CH₃COO）₂·2H₂O 0.25mol/L,NH₃·H₂O is 2.5mol/L and reaction time is 4h.Under the microscope,the reduction of permeate oil droplets was observed.The chemical oxygen demand of the emulsion decreased from 5418mg/L to 54mg/L,and the oil droplet size varied from 1μm～8μm to 0.2μm～0.7μm.The permeating is 1738.4L/m₂·h.After the circulation filtration,the purity of the permeate is above 99.1%,and the permeation flux decreases by a small amount.