| with the increasing amount of oil/water mixtures caused by food,metallurgy,petroleum,manufacturing,oil spill accidents and human life,effective separation and enrichment of oil in oil-water mixture has become an urgent challenge in industrial area and research community.However,conventional separation methods usually separate oilwater mixture by physical or chemical methods,such as gravity separation,flotation separation,centrifugal separation and electrocoagulation.These methods are costly,inefficient and waste valuable oil resources.Superwetting materials with opposite oil/water wettability exhibit many advantages in oil-water separation,such as intelligence,high efficiency and low cost.Therefore,it is significant that design the superwetting materials with high efficiency in oil-water mixture.Conventional superwetting materials usually use non-degradable porous membrane as the substrate,or even use toxic chemical reagents for surface modification.The extensive usage of these materials not only consumes precious petroleum resources continuously,but also brings serious secondary pollution.Due to its degradability,renewability,low dense,excellent flexibility,corrosion resistance and high porosity,cotton fabric has shown great application potential in oilwater separation.Therefore,superhydrophobic cotton fabric,superhydrophilicunderwater superoleophobic cotton fabric and dual underwater superoleophobic-under oil superhydrophobic cotton fabric were prepared and studied on oil/water separation performance.Cotton fabrics was used as the substrate.Zn O particles was grown and deposited on the cotton fabric surface by hydrothermal method to construct rough micro/nanostracture.Then the superhydrophobic cotton fabric with water contact angle of 155° in air was prepared by low surface energy modification with stearic acid.In addition,superhydrophobic cotton fabric shows excellent oil/water separation performance and selective oil absorption capacity.Superhydrophobic cotton fabric has good oil/water performance.Separation efficiency is above 96% and flux of oil is within the range of2000-9000 L·m-2h-1.The separation efficiency of superhydrophobic cotton fabric remained unchanged after ten times oil/water separation recycle,showing excellent robustness.Superhydrophobic CF exhibits excellent mechanical stability and environmental durability,which does not lose its superhydrophobicity after friction on sandpaper,ultrasonic treatment,immersion in boiling water for 60 min and immersion in organic solvents for 7 days.Environmentally friendly superhydrophobic cotton fabric can be as ideal candidate to replace the traditional non-degradable or even toxic superhydrophobic material.Superhydrophobic cotton fabric is more suitable for separating heavy oil and water mixture.It is necessary to develop superhydrophilic-underwater superoelophobic cotton fabric with excellent separation performance of light oils and water mixture.Polydopamine(PDA)particles were deposited in situ on the surface by dopamine oxidation polymerization to construct hierarchical micro/nanostructure,and then chitosan(CS)was used to further improve the hydrophilicity of the surface by hydrogen bonding and intermolecular forces,obtained the superhydrophilic-underwater superoleophobic cotton fabric with the underwater oil contact angle of 158°.Superhydrophilic-underwater superoleophobic cotton fabric has excellent oil/water separation performance.The separation efficiency is above 99% and the water flux is in the range of 15100‐30000L·m-2 h-1.The separation efficiency and water flux of superhydrophilic and underwater superoleophobic cotton fabric remain unchanged after ten oil/water separation recycle,exhibiting excellent stability.Due to the strong bonding between PDA,CS and cotton fabric,superhydrophilic and underwater superoleophobic cotton fabric exhibits excellent mechanical and chemical resistance.After immersion in acidic,alkaline and high concentration salt solutions for 7 days,the underwater oil contact angle remained unchanged.The friendly superhydrophilic and underwater superoleophobic cotton fabric exhibits great application potential in oil/water separation,due to the mild preparation condition,excellent separation performance and good stability.The superhydrophilic and underwater superoleophobic cotton fabric is also more suitable for separating light oil and water mixture.Therefore,it is necessary to fabricate the dual underwater superoleophobic and underoil superhydrophobic cotton fabric with the ability that can separate light oil or heavy oils and water mixture on demand.After surface activation by polyethylenimine of cotton fabric,tannic acid absorbed on Zn O particles were deposited on the surface by hydrothermal method,and then dual underwater superoleophobic and underoil superhydrophobic cotton fabric was fabricated.The water contact angle in oil is about 169° and water rolling angle in oil is about 1.5°.The oil contact angle in water is about 169° and oil rolling angle in oil is about 2.1°.Underwater superoleophobic and underoil superhydrophobic cotton fabric also shows excellent separation performance of heavy oil and light oil from water.When the underwater superoleophobic and underoil superhydrophobic cotton fabric is used to separate heavy oils and water mixture,the separation efficiency is over 97%.When the underwater superoleophobic and underoil superhydrophobic cotton fabric is used to separate light oils and water mixture,the separation efficiency is over 99%.In addition,underwater superoleophobic and underoil superhydrophobic cotton fabric also shows excellent stability to ultrasonic treatment.The underwater oil contact angle and underoil water contact angle of cotton fabric remained unchanged after immersion in boiling water or in organic solvents,exhibiting excellent environmental durability.Therefore,underwater superoleophobic-underoil superhydrophobic cotton fabric can be used to separate heavy or light oils and water mixture by pre-wetted method on demand,exhibiting great application potential in oil/water separation.In this paper,cotton fabrics were used as the substrate to fabricate the type of oil removing materials of superhydrophobic cotton fabric,the type of water removing material of underwater superoloephobic cotton fabric and double underwater supeoleophobic and underoil superhydrophobic cotton fabric for oil water separation.In oil-water separation test,superhydrophobic cotton fabric is more suitable for separating heavy oil/water mixture,the underwater superoleophobic cotton fabric is more suitable for separating the mixture of light oil and water,dual underwater superoleophobic-underoil superhydrophobic cotton fabric can separate the heavy oil/water mixture and light oil/water mixture.In addition,cotton fabric was used as the substrate to replace the non-degradable petroleum-based material to fabricate environmentally friendly superwetting material,which shows great application potential in oil-water separation. |
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