Creation Of Nanostructures On The Surface Of Carbon Fiber Cloth And Application In Oil-water Separation

With the increasing of environmental protection,the oils in the wastewater from offshore oil wells or industries must be removed with high-precision before discharge.However,the oil-in-water micro-droplet emulsion with high stability is intractable,which makes the oil removal a great challenge.In recent years,the advanced functional materials with effective emulsion breaking have caused increasing attention due to their high oil/water separation efficiency.Especially,superhydrophilic materials can suppress oil adhesion and flux degradation owing to their underwater oleophobicity,and accordingly exhibit superior demulsification performance.In the present work,a series of superhydrophilic and underwater superoleophobic composites were designed and prepared by creating nanostructures on the surface of carbon fiber cloth,and finally used for the separation of oil-in-water emulsion.The main results are summarized as follows:（1）Carbon fiber cloth modified with vertically aligned nanoblade-like zinc sheets（B-Zn/CFs）was prepared with the combination of hydrothermal and electrodeposition strategy.The ZIF-8 nanoparticles were pre-grown on the surface of carbon fiber cloth with hydrothermal method,which led to the ultrafast growth of Zn nanoblade-like structure during the subsequent electrodeposition process.The nanoblade-like structure can cut through and break the emulsions for oil removal.The parameters for the preparation of materials were optimized,and the structure-function relationship between the wettability and emulsion separation efficiency was explored systematically.It was revealed that the material with the electrodeposition time for 100 s exhibited excellent superhydrophilic and underwater superoleophobic wettability,achieving a separation efficiency as high as 99.72%with simultaneously exceptional emulsion flux of 962.95 L m^-2h^-1bar^-1.The B-Zn/CFs exhibited a sustained separation efficiency of over 98.53%after 10 cycles.Furthermore,the B-Zn/CFs showed high separation performance toward various oil-in-water emulsions,and excellent underwater superoleophobic wettability even under ultrasonic treatment and salt solution immersion.（2）Boron and nitrogen co-doped carbon nanotubes arrays were grown on the carbon fiber cloth（BNT/CFs）by high temperature pyrolysis method,using polyethylene glycol as carbon source,urea as nitrogen source and boric acid as boron source.Based on the examination with electron microscopy,wettability test and emulsion separation test,it was revealed that the BNT/CFs obtained via pyrolysis at 800℃for 6 h were surface grown with high-density,uniformly distributed carbon nanotube arrays,and showed excellent superhydrophilic and underwater superoleophobic wettability,as well as high emulsion separation efficiency up to 99.30%.After 10 cycles of emulsion separation,the materials still maintained a high separation efficiency（≥99.06%）and a high emulsion flux(≥971.11 L m^-2h^-1bar^-1).In addition,the BNT/CFs possessed good underwater superoleophobicity even under various harsh liquid environments,such as strong acid,strong alkali,high concentration salt solution,demonstrating their excellent recyclability and environmental stability.