Preparation And Performance Evaluation Of Superhydrophilic/Underwater Super-Oleophobic Cu?OH?₂ Mesh And Oil/Water Separation Experiment

A large amount of oily sewage is produced in oilfield production.The direct discharge of oily sewage would cause severe damage to the natural environment.The traditional oil-water separation methods have various disadvantages.The oil-water separation method based on special wettability is more efficient and environmentally friendly than the traditional method.super-wetting surfaces mainly include super-hydrophobic and super-lipophilic surfaces and super-hydrophilic and super-oleophobic surfaces.The inherent lipophilicity of superhydrophobic/super-lipophilic coatings causes oil droplets and oil impurities to easily adhere to the membrane surface during the oil-water separation process,causing membrane fouling,rapid decrease in membrane flux,poor hydrophobicity,and reducing separation efficiency.On the contrary,super-hydrophilic/super-oleophobic mesh can make up for the above disadvantages,and have broader application prospects.The solution-soaking method was used to prepare a super-hydrophilic/underwater superoleophobic oil-water separation reticulate membrane.A 200-mesh copper mesh was selected as the substrate.After immersed in the mixed solution(1:1 volume ratio)of sodium hydroxide solution for 60 minutes,the contact angle of the water droplets in the air was 0°,and the contact angle of the underwater n-hexane oil droplets reached 158°.Scanning electron microscopy was used to analyze the microscopic surface morphology of the copper mesh before and after treatment.The surface of the omentum after oxidation with potassium sulfate was uniformly grown with dense micron-line rough structures,arranged radially;after oxidation with potassium permanganate,the length of the micro-wire structure on the surface was shortened,the diameter was increased,and it was irregularly arranged.The behavior of water droplets and oil droplets on the surface of the omentum was analyzed by a contact angle measuring instrument.The water droplets in the air easily wet the copper mesh and spread on the surface of the copper mesh within 1s.The contact angles of the five test oil droplets of n-hexane,kerosene,gasoline,benzene 1,2-dichloroethane under water after treatment were all greater than 155°.The rough structure of the mesh membrane surface was analyzed by X-ray photoelectron spectroscopy to be copper hydroxide.The omentum has excellent heat resistance and seawater corrosion resistance.After heating the copper mesh to 210°C,the contact angles of the five oil droplets on the surface of the underwater omentum were all greater than 150°,The omentum soaked in saturated Na Cl solution for 72 h,the contact angle of kerosene under water was still greater than 155°.After the omentum moved 10 cm and 15 cm under the pressure of 50 g and 100 g weight respectively,the contact angle of the underwater oil drop were less than 150°,and the wear resistance still needs to be strengthened.The mesh membrane can efficiently separate the oil-water mixture of n-hexane,kerosene,gasoline,benzene,1,2-dichloroethane and water under the action of gravity.The separation efficiency exceeded 95%,and the separation efficiency of the 200 mesh copper mesh was the highest.The separation efficiency was the highest when the mesh number of the copper mesh was 200 and the oil-water ratio was 3:1,reaching 98%.After repeated use 30 times,the separation efficiency was still greater than 90%.