Studies On Fabrication Of Functional Stainless Steel Meshes With Ultrahigh Flux And Their Oil Water Separation Performance

With the development of modern industries and society,industrial oily wastewater and frequent oil leakage accidents resulted in serious environmental pollution,which is one of the major problems to be solved at present.Traditional oil-water separation methods are limited and unsatisfactory due to high cost,low separation efficiency and complex operation.Therefore,it is significant to develop and prepare functional membranes with special wettability for oil-water separation,such as superhydrophilic membranes and superlipophilic membranes.However,the separation membranes prepared often have shortcomings such as low flux and poor stability nowadays.Herein,a coupling agent modified stainless steel mesh and a poly（N-isopropylacrylamide）hydrogel coated stainless steel mesh with ultrahigh flux were prepared through grafting modification method.The main research work and results of this article are as follows:（1）Firstly,the original stainless steel mesh was coated with Ti O₂ through a liquid-phase deposition method to form a rough structure and introduce hydrophilic groups to the mesh.Then,the mesh surface was modified withγ-（methacryloxypropyl）trimethoxysilane（KH570）,in which case,hydrolytic polycondensation reaction took place on the mesh surface.Finally,a coupling agent modified stainless steel mesh was achieved（SSM-KH570）.The effects of deposition time,coupling agent concentration and hydrolysis polycondensation reaction time on SSM-KH570 surface hydrophobicity were discussed,and the oil-water separation performance of SSM-KH570 was evaluated.The research results showed that the hydrophobicity of stainless steel mesh surface modified by coupling agent after liquid deposition for 10 hours was the best.When KH570 volume concentration was 3%,and the reaction time was 30 min,the surface hydrophobicity was the best.At this time,the water contact angle was 150.6°and the oil contact angle was 0°,which achieved superhydrophobicity and superlipophilicity.The oil-water separation test exhibited that the separation efficiency of SSM-KH570 was 98%,and the flux was10000 Lm^-2h^-1.More importantly,the separation performance did not decrease significantly after continuous separation for 10 times.（2）First,a functional stainless steel mesh with reactive C=C double bond on the surface was prepared through taking the best preparation parameters of SSM-KH570.Then,polymer poly（N-isopropylacrylamide）（PNIPAM）was grafted onto the modified mesh surface by thermally initiated free radical polymerization.Thus,a poly（N-isopropylacrylamide）modified stainless steel mesh was prepared（SSM-PNIPAM）.The research results demonstrated that PNIPAM which formed a three-dimensional network rough structure on the mesh surface under the action of crosslinking agent（MBA）was grafted onto the mesh surface successfully.The effect of the amount of crosslinking agent on the surface morphology and structure of SSM-PNIPAM was preliminarily studied.The experimental results showed that the amount,morphology and structure of the hydrogel adhered on the mesh surface can be controlled by adjusting the amount of MBA.（3）The surface wettability,oil-water separation performance,various stabilities and pressure resistance of SSM-PNIPAM were studied.The research results showed that SSM-PNIPAM exhibited superhydrophilicity,underwater superhydrophobicity and excellent anti-oil properties.What’s more,SSM-PNIPAM showed excellent separation performance for most oil-water mixtures.The mesh showed high-efficiency separation ability（99.2%）and ultrahigh flux(23000 Lm^-2h^-1).Importantly,SSM-PNIPAM exhibited excellent surface wettability stability,chemical stability and recycling performance.Finally,it was calculated that the critical surface pressure of SSM-PNIPAM was 1294 Pa through the osmotic pressure test.