Fabrication Of Materials With Special Wettability And Their Application In Oil-water Separation

The ever-increasing industrial oily wastewater and frequent oil spill accidents have not only caused a great loss of energy,but also severely threatened ecosystem and human beings' safety.With the rapid development of interface science and bionics,many materials with special wettability have been prepared and could realize rapid and efficient oil-water separation.It is well known that a surface with special wettability depends on the combination of rough micro/nano-scale structures together with surface free energy.According to this basic principle,we chose copper mesh,cotton fabric and stainless steel mesh such conventional materials as substrates,and prepared several functional materials with special wettability to separate oil/water mixtures under different requirments.In this paper,the research contents are as follows:(1)A Cu2 S and Cu2 O composite(Cu2S@Cu2O)film with micro/nano binary structure was created on copper surface by a facile chemical bath deposition method.After modification with low-cost polydimethylsioxane(PDMS),the superhydrophobic Cu2S@Cu2O film was obtained.The as-prepared film shows outstanding water repellency with a water contact angle larger than 150° and long-term storage stability.Moreover,the same method was used to fabricate superhydrophobic/superoleophilic copper mesh,and it could realize separation of various oily sewages with separation efficiency above 94%.(2)A superhydrophobic/superoleophilic cotton fabric was fabricated by a facile one-step dip-coating method using a crosslinkable fluorinated copolymer material-Poly(methyl methacrylate-co-butylacrylate-co-hydroxyethyl methacrylate–co-perfluoroalkylethylmethacrylate-co-stearyl methacrylate-co-methacrylisobutyl polyhedral oligomeric silsesquioxane)(P(MMA-BA-HEMA-FMA-SMA-MAPOSS)).The copolymer was synthesized using a conventional solution free radical polymerization.The coated cotton fabric has a water contact angle above 150° and oil contact angle of 0°,showing both superhydrophobicity and superoleophilicity.Furthermore,the cotton fabric could keep its superhydrophobic property even after ultrasonic treatment in ethanol or thermal treatment,as well as for acidic or alkaline liquids.The coated cotton fabrics were used to separate various oil-water mixtures with separation efficiency all above 96%.Additionally,the cotton fabrics still kept high separation efficiency above 98% after 50 separation times for n-hexane/water mixture.(3)To solve the problem of easy oil fouling of superhydrophobic/superoleophilic materials,a durable underwater superoleophobic mesh was conveniently prepared by layer-by-layer(LBL)assembly of poly(diallyldimethylammonium chloride)(PDDA)and halloysite nanotubes(HNTs)on a stainless steel mesh.The hierarchical structure and roughness of the PDDA/HNTs coating surface were controlled by adjusting the number of layer deposition cycles.When the PDDA/HNTs coating with 10 deposition cycles was decorated on the mesh with pore size of about 54 ?m,the underwater superoleophobic mesh was obtained.The as-prepared underwater superoleophobic PDDA/HNTs decorated mesh exhibits outstanding oil-water separation performance with a separation efficiency of over 97% for various oil/water mixtures.Meantime,the separation mechanism for the oil/water mixture was also elaborated.In addition,the as-prepared decorated mesh still maintained high separation efficiency above 97% after repeated 20 separation times for hexane/water mixture or chloroform/water mixture.More importantly,the as-prepared decorated mesh is durable enough to resist chemical and mechanical challenges,such as strong alkaline,salt aqueous and sand abrasion.Therefore,the as-prepared decorated mesh has practical utility in oil-water separation due to its stable oil-water performance,remarkable chemical and mechanical durability and the facile and eco-friendly preparation process.