Fabrication And Application Research Of Functionalized Superwetting Materials In Oil-water Separation

With the rapid development of industrialization,oily wastewater has posed a great threat to environment and human health.However,the traditional oil-water separation technology has the disadvantages of high cost,high energy consumption,low separation efficiency,and easy to cause secondary pollution to the ecological environment.The design of superwetting materials provides a new idea for oil-water separation technology.Inspired by the special wettability of biological surfaces in nature,researchers have designed a series of oil-water separation materials with special wettability,such as oil removal type and water removal type materials.However,most oily wastewater has high viscosity and contains a variety of hazardous organic substances in the actual complex environment.The material with single wettability unable to meet the increasing demand of oil-water separation.Therefore,the functional superwetting materials which could overcome some disadvantages of the material with single wettability were emerged.In this thesis,two kinds of functional superwetting materials were fabricated,including the pH-bidirectional responsive fabric with switchable wettability and the superhydrophobic absorbent with electrothermal/photothermal conversion performance,which could realize the separation of multiple organic components and the separation of high viscosity oil-water mixture.Based on the present research status,this thesis choose the polyester fabric and absorbent cotton as base materials,with the help of the pH-responsive chemical components synthesised by the radical polymerization,the electrothermal/photothermal conversion composite particles fabricated by liquid-phase reduction method,and the low surface energy modified agent to fabricate the functionalized superwetting materials.This thesis is segmented into the following two sections:(1)The pH-bidirectional responsive fabric with switchable wettability was fabricated by simple free-radical polymerization and dip coating methods.SiO2 and MgO particles were used to construct micro/nano layered rough structures on the fabric surface,and combined with alkali sensitive copolymer,acid sensitive amino silane and the modification of the silane with low surface energy to obtain the modified fabric.The modified fabric could achieve reversible wettability conversion in the pH range of 1-13,and be used for efficient separation of various oil-water mixtures and controlled separation of three-phase oil-water-oil mixtures.The separation efficiency and flux expectively exceeded 98.8%and 6400 L· m-2·h-1,while showing excellent mechanical durability and chemical stability.The modified fabric can separate phenol and aniline from phenol/aniline/anisole mixture system with the separation efficiency of 90.18%and 90.84%,respectively.In addition,the modified fabric could separate harmful organic components from the mixed system of multiple organic components.Based on the above advantages,the pH-bidirectional responsive fabric with switchable wettability would have a broad application prospect in the field of oil-water separation under complex environment.(2)The superhydrophobic absorbent cotton with electrothermal/photothermal conversion performance was fabricated by liquid-phase reduction and layered assembly methods.The resulted superhydrophobic absorbent cotton was loaded with Cu/carbon microspheres composite particles with electrothermal/photothermal conversion performance and bonded with the modification of low surface energy long-chain silane.The water contact angle(WCA)of modified cotton reached 154°.The separation efficiency of superhydrophobic absorbent to a variety of oil and water mixtures exceeded 98.3%.The surface temperature of superhydrophobic absorbent cotton had reached the maximum value when the sunlight irradiated for 45 s,so it could be used in the absorption-removal process of crude oil/water mixture.The absorption-removal process of oil-water mixture with high-viscosity and low melting point solid oil-water mixture,and the fast separation process of crude oil/water mixture could be realized under applied low-voltage.At the same time,it exhibited excellent chemical stability and recyclability.Based on the above advantages,the fabricated superhydrophobic absorbent cotton would have a broad application prospect in the fields of high viscosity oilwater separation and oily wastewater treatment.