Preparation Of Superhydrophilic And Underwater Super-oleophobic Composite Mesh And Its Performance Of Oil Water Separation

With the development of modernization in the world,the increase of the oil leakage caused by offshore oil exploitation and the discharge of industrial oily wastewater has led to a decline in the total amount of pure water on the earth and caused serious damage to the ecological environment.Therefore,the treatment of oily wastewater needs to be resolved.In recent years,superhydrophilic and underwater superoleophobic porous materials,especially metal mesh as the base material,have attracted the attention of researchers,However,the resistance to the complex environment,simple preparation,and environmental protection of these materials have always been the research direction of researchers.This article is devoted to the study of oil-water separation materials that are resistant to complex environmental conditions,simple preparation,and environmental protection by using stainless steel mesh.The main contents are as follows:1.Using a two-step immersion method,a superhydrophilic and underwater superoleophobic double-coated mesh was successfully prepared.The inner coating material,a polycarbonate polyurethane（PCPU）whose terminal group is C=C,was first synthesized,and then was coated onto a stainless steel mesh.Next,the outer coating polyethylhexyl acrylate（PHEA）was grafted onto the PCPU coating by radical polymerization to obtain a superhydrophilic and underwater superoleophobic PCPU-mesh（HPCPU-mesh）.The HPCPU-mesh has high stability due to the combined effect of the water resistance,heat resistance of the inner coating,strong adhesion between the inner coating and the stainless steel mesh,and the chemical cross-linking between the outer coating and the inner coating.Under the following conditions:soaking in water for 30 days,soaking in hot water at 80°C for 5 days,immersing in 0.5M HCl,0.5M Na OH and 0.5M Na CI solution for 24 hours,and immersing in five oils for 5 days,HPCPU-mesh still has not less than 99.7%separation efficiency.And the effect of preparation conditions on separation performance was also studied.2.Using a one-step immersion method,the stainless steel mesh was immersed in an aqueous solution containing HCl and gluconic acid（GA）to successfully prepare a superhydrophilic and underwater superoleophobic stainless steel mesh（GA-mesh）.GA-mesh exhibits excellent separation capabilities,including more than 98%separation efficiency for various oil-water mixtures,good stability in complex environments,and high flux(140 L m^-2s^-1).The influence of the number of mesh on the separation performance was also investigated.It was found that the separation efficiency and the invasion pressure increase with the raise of the number of mesh,but as for flux the result is the opposite.Therefore,the number of mesh can be adjusted to meet actual needs.3.The stainless steel mesh is immersed in gelatin（Gelatin）solution to prepare Gelatin-mesh.The Gelatin-mesh is treated with（NH₄）₂SO₄ solution（salt-treated）to successfully prepare superhydrophilic and underwater superoleophobic salt-treated-Gelatin-mesh（S-Gelatin-mesh）.S-Gelatin-mesh exhibits excellent oil-water separation performance,including good reusability,corrosion resistance,high separation efficiency（above 99.6%）.In addition,this method can achieve no waste of raw materials and stainless steel can be recycle and re-use.