Fabrication Of Superhydrophilic And Underwater Superoleophobic Copper Mesh And Research On Oil-water Separation Performance

Separation and purification of oily sewage is one of the global scientific problems.However,cumbersome preparation process,poor stability,and poor anti-fouling performance limit the wide application oil-water separation membranes.In the paper,by designing and controlling surface morphology and chemical composition of copper meshes,two superhydrophilic meshes were prepared.Efficient separation of the oil-water mixture was realized with the as-prepared meshes.The main research contents are as follow:（1）In order to simplify preparation process,improve chemical stability and oil resistance of separation membranes,PAM/SiO₂ coating was modified on the surface of copper mesh through layer-by-layer（LBL）assembly method in order to prepare a superhydrophilic mesh.The roughness of PAM/SiO₂ coating could be adjusted by the number of deposition.The adhesion between PAM/SiO₂ coating and copper mesh could be enhanced by sodium alginate.After modification,the mesh with ideal pore size has a high underwater oil contact angle of154.32°.The water capture percentage raised to 33.52%.The mesh was durable enough to resist acid solution,salt solution and various organic solvents.It was suitable for oil-water separation in complex environment.The as-prepared mesh had practical utility in oil-water separation due to its low-cost,simple and the eco-friendly preparation process.With all these advantages,it had good application prospect in oil-water separation.（2）The underwater superoleophobic mesh was prepared by chemical etching and LBL assembly method.Firstly,rough micro nano structure on the surface was constructed by chemical etching.Secondly,hydrophilic CS/PSS-HNTs coating was decorated on the surface of copper mesh.The effects of solution concentration,etching time and modification on micromorphology and wettability were studied in detail.After etching and modification,the underwater oil contact angle raised to 155.19°and oil sliding angle was 2.5°.The adhesion between the membrane and oil was extremely low.The decorated mesh was durable enough to resist chemical and mechanical challenges,such as strong alkaline,salt aqueous solution and sand abrasion.After immersion in alkaline and salt solution or sand impact,the mesh maintained stable wettability and excellent oil-water separation performance for hexane/water mixture.（3）Oil-water separation efficiencies of both meshes were tested with various oil-water mixtures（n-hexane/water,dichloromethane/water,petroleum ether/water,isooctane/water,kerosene/water,cooking oil/water）.Both meshes can separate most of the floating oil/water mixtures.After separating n-hexane/water mixture for 20 times,separation efficiencies of both meshes remained above 96.5%.Intrusion pressure of both meshes was above 1.4 KPa and the permeation flux was above 4000 L/（m²·h）.From the comparation of both meshes,the separation efficiency of APS-CM-8 was higher and the reusability was better,while the mesh with CS/PSS-HNTs coating had higher oil pressure and permeation flux.Since both meshes had their own advantages and disadvantages,the qualified membrane could be selected according to the separation requirement to achieve efficient oil-water separation.