Fabrication Of Metal Meshes With Special Wettability And Their Application In Oil/Water Separation

With the rapid development of the global industrialization process,the fields of oil exploitation,metallurgy,steel,leather,chemicals,oil spill and so on frequently produce a lot of oily wastewater everyday.This direct discharge of oily wastewater of is not only a serious waste of non-renewable resources,but also a directly pollution to the environment,indirectly affect the human health and life.Therefore,the separation of oily wastewater is of great significance no matter from saving resources or protecting the environment.Common methods to separate oil/water mixture including physical,chemical,biological methods.These methods have their own advantages,but its footprint,energy consumption,separation efficiency need to be further improved.In recent years,it is found that the surface of the lotus leaf is composed of a layer of papillae waxy structure through the study of the surface morphology and chemical composition of lotus leaf.The surface of lotus leaf with superhydrophobic property aroused great interest.By the principle of bionics,it needs two necessary condition to obtain superhydrophobic properties: increasing surface roughness and reducing surface free energy.Inspired by this,a large number of studies have focused on superhydrophobic studies and have been successfully applied in oil and water separation.In this paper,the superhydrophobic Co?OH?₂/HDTMS stainless steel mesh,superhydrophilic/underwater superoleophobic Co?OH?₂CO₃?CoCO?nickel mesh and superhydrophobic CoOC/HDTMS nickel mesh were successfully prepared.And a set of oil/water separation device was designed to study its oil/water separation performance.First of the work,stainless steel mesh as the substrate,a layer of butterfly wings with Co?OH?₂ rough structure was synthesized on stainless steel mesh?SS?surface by electrochemical method,and then modified with low surface energy of hexadecyltrimethoxysilane?HDTMS?,and finally obtained superhydrophobic properties.The surface contact angle of the superhydrophobic screen surface can reach 157.9° and the oil contact angle is 0°,so it can be successfully applied in oil/water separation.The results show that the separation efficiency of the superhydrophobic SS mesh to hexane/water,isooctane/water,petroleum ether/water,gasoline/water and diesel/water can be higher than 99.5% and after 25 times?hexane/water mixture as an example?separation,the mesh can still maintain a high superhydrophobic performance and separation efficiency.Moreover,the mesh has a good weather resistance,which is due to the modified silicone layer with a natural antioxidant capacity,can effectively prevent the corrosion of external oxides,which can play to a very important role in dealing with corrosive oil and water mixture.In addition,the mechanical properties of superhydrophobic mesh is also investigated.Secondly,the Co?OH?2CO3?CoOC?rough structure was formed by hydrothermal method on the surface of nickel mesh.The contact angle of the surface water was 0°,and the contact of the underwater oil angle of 158.1°,showing excellent superhydrophilic / underwater superoleophobic properties.After the CoOC Ni mesh was chemically modified with hexadecyltrimethoxysilane?HDTMS?,a superhydrophobic / superoleophilic surface maintaining a water contact angle of 157.2° and an oil contact angle of 0° wan obtained.Finally,this paper designed a set of continuous oil/water separation device,the above two with the opposite wetting performance of the meshes clip on both sides of the device to achieve continuous separation of oil and water mixture.This method overcomes the shortcomings of batch operation of single membrane oil/water separation device,low purification degree and so on,and enlarges its application range.More importantly,since the modified Si-O-Si bond on the surface of the Ni mesh has a high bond energy,the heat resistance of the superhydrophobic mesh has been greatly improved,which provides a new way in the separation of the oily wastewater at higher temperatures.