Wettability Of Metallic Nano-oxides And Further Application In Oil/water Separation

Wettability is an important property of material, which is mainly determined by the compositon of material surface and micro structure. For instance, lotus leaf is superhydrophobic. It has a water contact angle as large as 161°. This wettability is based on the epicuticular wax covered on the surface and the micrometer-scale papillae on the leaf. It is important to research material’s wettability in order to design materials with function such as water-collecting, anti-fogging, and separating. In common sense,material has 4 different special wettability: superhydrophobic/superhydrophilic,superoleophobic/superoleophilic. The combination of different special wettability is meaningful to design functional material.Respectively, materials with special wettability could be used in oil/water separation. For example, stainless steel mesh covered with PTFE is superhydrophobic and superoleophilic. Oil could easily permeate through the mesh while water could not.Mesh covered with PAM hydrogel is superhydrophilic and superoleophobic, thus water could permeate but oil could not. “use special wettability in oil/water separation” is the guideline of the research in this article.Metal oxide is the material we mainly used in this research. Using a simple hydro-thermal method, nanostructure consist with zinc oxide and tungsten oxide is successfully grown on a mesh substrate. The as-prepared mesh is superhydrophilic in the air and superoleophobic underwater, and it could efficiently separate oil and water.Meanwhile, mesh grown with zinc oxide could be used for photo-degradation, and mesh grown with tungsten oxide could be used in demulsification.Except of metal oxide, we also use other material in oil/water separation.We’ve prepared a nylon mesh covered with cellulose hydrogel, which could be used in high-efficiency oil/water separation. We’ve also made a colander with this mesh, which could scoop oil from water. In the last research, we’ve modified a copper foam with silane. Using a simple electrode process, we could switch it’s wettability from superhydrophobic to superhydrophilic. This switch could be used to control water permeation of the mesh.