Study On Oil/Water Separation Of Superhydrophobic And Self-cleaning Stainless Steel Mesh

Oil spill is the main factor of marine ecosystem pollution,which seriously affects the balance of water environment and threatens marine biodiversity.It is crucial to search an efficient and feasible method to separate oil from water.In this paper,stainless steel meshes were used as the base material,and the surfaces of meshes were modified by dip-coating method to build novel superhydrophobic and self-cleaning surfaces,which endow the stainless steel meshes oil/water separation and anti-fouling performance.Firstly,200-mesh,300-mesh and 400-mesh were used as the base material,and the surfaces were modified by polyaniline/titanium dioxide（PANI/TiO₂）composite coating by dip-coating method.Three kinds of superhydrophobic PANI/TiO₂ modified meshes with different mesh numbers were prepared,and properties of stainless steel meshes before and after modification were studied.Compared with original stainless steel meshes,the PANI/TiO₂ modified meshes surface exhibited an obvious larger roughness and hydrophobicity.The static water contact angles increased from 92°,93°and 96° to 152°,154° and 158° respectively,indicating that PANI/TiO₂ modified meshes possessed excellent superhydrophobic property.The mechanical abrasion experiment results showed that the static water contact angle of PANI/TiO₂ modified mesh kept above 150° after 100 times mechanical abrasion,remaining superhydrophobic property.In addition,the permeate fluxes of PANI/TiO₂ modified mesh for hexane,decane,toluene and diesel oil were all above 40k L·m-2·h-1,and the oil purities in permeate were higher than 99.7%in oil/water separation experiment.After 100 cycles separation experiments,the static water contact angle of PANI/TiO₂ modified mesh only decreased by 3°.Photocatalytic degradation experiments showed that PANI/TiO₂ composite coating could effectively degrade oil and organic contaminants on the surface of stainless steel meshes.After immersed in 3.5 wt%NaCl solution for 60 hours,the results of electrochemical impedance spectroscopy showed that PANI/TiO₂ modified meshes had good corrosion resistance.Secondly,epoxy resin and graphite fluoride（FG）nanosheets were used for surface modification of 200-mesh,300-mesh and 400-mesh,and the modified stainless steel meshes with superhydrophobic and self-cleaning properties were prepared.The contact angle test results indicated that the hydrophobicity of the stainless steel meshes increased dramatically after modification by FG,showing superhydrophobic properties.The oil/water mixture of hexane/water,dichloromethane/water,decane/water,toluene/water and diesel/water can be separated rapidly through the FG modified steel mesh under its own gravity,with the water was retained on the steel mesh,and the oil passed through the FG modified steel mesh.After 100 cycles separation experiments,the permeate fluxes and separation efficiencies of FG modified steel mesh had no significant change.After 100 cycles mechanical abrasion,the static water contact angle of FG modified mesh decreased by only 6.4%and remained basically stable.