Preparation Of Membrane-based Super-Wetting Materials And Their Application Research On Oil-water Separation

In the process of social development,human production activities produce a large amount of oily wastewater.How to deal with oily wastewater has becomed a hot spot in today’s society.However,the traditional separation technology can not effectively solve the problem of wastewater pollution,so membrane-based filtration separation materials have becomed a future development trend.Based on the theory of wettability,we developed two different membrane-based separation materials,respectively,superhydrophobic-superlipophilic membrane and superhydrophilic-underwater superoleophobic membrane.We assembled the separation materials and the separation tank into a separation device for oily wastewater treatment.The specific work of this paper is showed as following:(1)Preparation of superhydrophobic-superlipophilic membrane.The superhydrophobic separation membrane with micro-nano structures were prepared by etching in acid solution containing copper ion,immersing in stearic acid solution and modifying with polytetrafluoroethylene(PTFE).Duing to the uniform coverage of PTFE spheres on the surface of micro-nano structures,the membrane had superhydrophobic property,and the contact angle of water droplet in the air was about 156°.The experiments showed that superhydrophobic membrane had the ability of acid and alkali resistance,self-cleaning and excellent stability.After 50 consecutive separation experiments,the separation efficiency of the superhydrophobic membrane remained around 96%.(2)Preparation of superhydrophilic-underwater superoleophobic membrane.We used electrodeposition technology to synthesize flake nickel hydroxide on the surface of stainless steel mesh.The micro-nano structures were constructed to increase the surface roughness of the mesh,which made the separation membrane more hydrophilic and more oleophobic under water.The contact angle of underwater oil droplet was about 162°.After 50 consecutive separation experiments,the separation efficiency of the superhydrophobic membrane remained around 96%.(3)Assembly of oil-water separatior and its separation performance.Two kinds of separation membranes with different sizes(2 × 4 cm and 28 x 28 cm)were prepared.We installed the prepared superhydrophobic membrane and superhydrophilic membrane in the L-shaped separation tank to separate the oily wastewater.The experimental results showed that the separation device could continuously process oily wastewater with the treatment capacity of about 4000 L/(m3·h)and the separation efficiency of about 95%.In conclusion,the strategy of large-scale preparation of special wetting materials by chemical etching、coating and electrodeposition is effective.Large-scale separation membranes are installed in small or medium-sized separators to treat oily wastewater on a large scale,which has a broad application prospect.