Preparation Of Superhydrophobic Coating On Cotton Fabric And Their Oil-water Separation Performance

Water conservation and governance are related to ecological development and human health.The leaked oil and oily wastewater are one of the main causes of water pollution,therefore,how to effectively treat oil-contaminated wastewater has become one of the focused hotspots of researchers.In recent years,with the development of biomimetic interface materials,porous materials with super-wetting properties have been used for oil-water separation.There are some differences between different liquids about the surface tension,so that special wettability materials exhibit different wetting properties for different liquids.The difference in surface tension between oil and water is widely,so special wetting materials which have opposite wettability for oil and water can be used to separate the oil-water mixture.In this paper,oil-water separation materials with superhydrophobic/superoleophilic properties were prepared with porous cotton fabric substrate.The main research contents are as follows:A novel superhydrophobic fabric coating was successful fabricated via a facile ultrasound-assisted in situ growth method.At first,Tetraethylorthosilicate?TEOS?and n-Dodecyltrimethoxysilane?DTMS?were mixed in anhydrous ethanol.And then under NH₃?H₂O catalytic and ultrasound-assisted,TEOS and DTMS were hydrolyzed and co-condensed to form hydrophobic SiO₂ on the surface of fabric by one step.The effects of the amount of DTMS and NH₃?H₂O on surface morphology and water contact angle?WCA?of the fabric were investigated.Water-repellency,Anti-fouling,Chemical stability and durability,mechanical stability and oil/water separation efficiency were evaluated.The WCA of the prepared fabric can reach 154.5�when the amount of TEOS,DTMS and NH₃?H₂O were 0.3 g,0.2 g and 3 ml,respectively,the time of ultrasound was 2 h.The superhydrophobic cotton fabric displays a good resistance to five kinds of the common household liquids,outstanding stability after immersed in various solvents for 72 h.The WCA can maintain above 150�with a little decrease after 10 times sandpaper?1000 mesh?abrasion test under 100 g of weight.At the same time,the application of the superhydrophobic cotton fabric in oil-water separation was explored.The results showed that the superhydrophobic cotton fabric possess high separation efficiency and good reusability.The preparation mechanism of the superhydrophobic fabric was analysised.PDMS-CuSA₂@fabric superhydrophobic coating has been fabricated on cotton fabric via in situ growth copper stearate?CuSA₂?and subsequent rational coating with Polydimethylsiloxane?PDMS?by dip-coating method.CuSA₂ could construct micro/nano-structure.CuSA₂ is used as a micro-nanoparticle for building roughness,micron-scale fibers and nanoparticles together construct hierarchical micro/nanoscale rough structure required for superhydrophobicity.The long alkyl chains from stearic acid?SA?provide the low surface energy.PDMS with network structure cover on the surface of fabric after cross-link curing,which can enhance the stability and durability of the coating.When the additions were 0.3 g of CuCl₂,0.3 g of SA and 1.2%PDMS,the prepared PDMS-CuSA₂@fabric possess the optimal superhydrophobicity,WCA=158.5�.A series of tests including the tape peeling test,sandpaper abrasion test,ultra-sonication treatment and the laundry test demonstrate the superhydrophobic fabric coating possessed good mechanical durability.Additionally,the fabricated superhydrophobic fabric can be applied in separating oils from water with high separation efficiency??90%?for five kinds of oil,the obtained superhydrophobic fabric maintained good reusability with above 96%of the separation efficiency for the n-heptane/water and dodecane/water mixture after 50 separation cycles.