Preparation Of Super-oleophobic/Super-hydrophilic Coating And Its Oil-water Separation Performance

With the progress and development of human society,the treatment of industrial oil spills and oily wastewater has become an important problem to be solved.The separation of oil-water mixture is not only beneficial to the conservation of resources,but also has a positive effect on the ecological environment and even human health.Super-oleophobic/super-hydrophilic materials with opposite wettability to oil and water have attracted widespread attention,and some groups have prepared super-oleophobic/super-hydrophilic surfaces that exhibit good super-wettability,but there are still problems such as poor mechanical durability,single oil-water separation environment,and low practicality.To solve these problems,a series of super-oleophobic/super-hydrophilic coatings were prepared in this study and their properties were systematically investigated as follows:(1)To investigate the effects of nanoparticle content,particle size and type on the wettability of composite coatings.Perfluorooctanoic acid,sodium hydroxide and poly(dimethylammonium chloride)were selected to modify the nanoparticles and then sprayed on the surface of the slide substrate to obtain the super-oleophobic/super-hydrophilic coating.The results show that the increase of nanoparticle content can improve the wettability of the prepared coatings to a certain extent,and the coatings prepared with small size nanoparticles have better super-oleophobic/super-hydrophilic properties,and the coatings prepared with nano-silica have better wettability than nano-titanium dioxide.The film-forming method of the coatings was also discussed,and the mechanical durability of the coatings was improved to a certain extent by the alternating spraying method of super-oleophobic/super-hydrophilic coatings and epoxy resins.(2)To further enhance the mechanical durability of the coating,this study proposes for the first time to prepare a highly mechanically durable oil-water separation mesh with a reinforced concrete-like structure by spraying carbon nanotubes,nano-silica and resin with oleophobic/hydrophilic modification reagents.The results show that when the epoxy resin content is 1ωt%and carbon nanotube content is 1.5ωt%,the prepared coating has good super-wettability with oil contact angle of 155.5°and water contact angle of 0°.After 160 times of sandpaper abrasion experiments,it still maintains the super-oleophobic/super-hydrophilic state and shows excellent mechanical durability.(3)In order to further enhance the oil-water separation performance of the modified stainless steel mesh,perfluorooctanoic acid and chitosan quaternary ammonium salt were selected to modify the nano-silica alkaline hydrolyzed by ethyl orthosilicate,while doping with carbon nanotubes and hydrophilic hydroxy acrylic resin,spraying the modified stainless steel mesh with good oil-water separation efficiency and permeation flux was prepared.The results show that the prepared modified stainless steel mesh can effectively separate a variety of oil and water mixtures,has good weather resistance,and can maintain good oil-water separation performance in a variety of harsh environments,and has a separation efficiency of more than 96%and a permeate flux of more than 1.6×10~4L/(m~2·h)in a mixture of oil and water(alkaline,acidic,neutral),and after 20 separations the separation The efficiency is 96.33%,with good reuse performance.