Preparation Of Light Driven Antifouling TiO₂ Composite Membrane And Study On Its Oil/Water Separation Performance

A large amount of oily sewage into the water environment not only seriously polluted water resources,but also can cause huge economic losses.Traditional oil/water separation methods including centrifugal,sedimentation,filtration and flotation have limited because of their low separation efficiency,the high cost and secondary pollution.Therefore,it was highly urgent to exploit an efficient oil/water separation method.In recent years,superwetting materials have made important applications in oil/water separation because of their high efficiency,simplicity and low energy consumption.The superwetting materials mainly include superhydrophobic/superoleophilic material and superhydrophilic/underwater superhydrophobic materials.Due to the lipophilicity,superhydrophobic/superoleophilic materials was easy to be contaminated by oil droplets,leading to weak flux and regeneration.Inspired by fish scales and mussels,researchers designed superhydrophilic/underwater superhydrophobic materials with high flux and regenerability.However,at present,there were still some problems such as high cost,easy pollution and poor regenerability of superhydrophilic/underwater superhydrophobic materials that need to be further solved.Titanium dioxide?TiO₂?,a kind of semiconductor material with UV light-driven ability,has become one of the common materials in daily life because of its stability,non-toxicity and low cost.TiO₂-based light response materials with excellent light-driven self-cleaning ability have become an ideal element for the construction of super antifouling materials.In this paper,TiO₂ was used as the building element to prepare the superhydrophilic/underwater superhydrophobic composite membrane with excellent antifouling and regeneration properties.The physical and chemical properties of the composite membrane were analyzed in detail,such as micro-morphology,chemical composition and surface wettability.The main research contents are as follows1.Preparation of UV-driven antifouling PF@PDA@TiO₂ and its oil/water separation performanceUsing paper fibers?PF?as substrate,TiO₂ nanowires were immobilized on PF by polydopamine?PDA?.The composite membrane?PF@PDA@TiO₂?was obtained by vacuum assisted filtration.The effects of the amount of TiO₂ nanowires on the surface morphology,wettability,separation efficiency and flux of the membrane were studied.After many experiments,the performance of PF@PDA@TiO₂-4?4 represents the amount of TiO₂ nanowires is 0.04 g?was the best,the contact angle of underwater oil?dichloromethane??OCA?is 156°,showing excellent underwater superoleophobicity.The separation efficiency of various oil/water mixtures was more than 99%,the flux was as high as 7000 L·m^-2·h^-1,and the oil adhesion is low.Regeneration experiments showed that after multiple oil/water separations of the membrane have been contaminated,the membrane can recover its separation performance after 1 hour of UV irradiation.After 80 oil/water separation cycles,the membrane can still maintain the underwater superoleophobicity,showing excellent UV driven antifouling performance and regeneration performance.In addition,the composite membrane also has an intrusion pressure of 3239.9 Pa and excellent stability.2.Preparation of visible light-driven anti-fouling CF/Co-TiO₂ and its oil/water separation performanceUsing carbon cloth fibers?CF?as the substrate,a one-step solvothermal method was used to prepare visible light-driven Co-doped TiO₂ composite membrane?CF/Co-TiO₂?.The effects of the amount of CoCl₂·6H₂O on its micro-morphology,wettability and separation performance were studied.After many experiments,CF/32Co-TiO₂?32 represents CoCl₂·6H₂O is 32 mg?has the best separation performance.The underwater OCA was 158°,and the adhesion of the underwater oil was very low,showing outstanding underwater superoleophobicity.At the same time,the separation efficiency of the membrane for various oil/water mixtures reached99.8%,and the flux was as high as 25089 L·m^-2·h^-1.After several times of oil/water separation fouled,the membrane can restore the separation performance after irradiated 1 h under visible light.After 110 times of oil/water separation cycle,the membrane can still maintain the underwater superoleophobicity,showing excellent visible light-driven antifouling performance and regeneration performance.In contrast experiment 1 and experiment 2,the UV light with very low utilization rate was transformed into visible light increasing the light absorption,and the underwater OCA was increased,the separation performance was higher,the hydrophobic effect was better,and the recycling and regeneration performance was stronger.3.Preparation of CF/TiO₂/Bi₂MoO₆ with visible light-driven antifouling property and its oil/water separation and catalytic PerformanceUsing CF as the substrate,CF-supported TiO₂?CF/TiO₂?was prepared by hydrothermal method,then TiO₂/Bi₂MoO₆ heterojunction composite membrane?CF/TiO₂/Bi₂MoO₆?supported on CF was prepared by solvothermal method.After many experiments,it was proved that CF/TiO₂/Bi₂MoO₆0.6?0.6 represents Bi?NO₃?₃·5H₂O:Na₂MoO₄·2H₂O=1.2:0.6?has the best separation performance,the underwater OCA was 158°and oil adhesion was low.The separation efficiency for various oil/water mixtures was 99.5%,and the flux was as high as 33600 L·m^-2·h^-1.In addition,the membrane could almost degrade methyl blue?MB?into colorless in 14min,showing excellent catalytic performance.At the same time,the fouled membrane could degrade the oil in 20 min to restore the separation performance,showing excellent visible light-driven antifouling performance.After 140 times of oil/water separation cycle,it can still maintain excellent separation performance,showing super antifouling performance and regeneration performance.Compared with experiment 2,experiment 3 has higher flux,better light absorption and degradation ability.In experiment 3,the degradation time of oil pollution by visible-light driven was shortened,which indicated the antifouling and the regeneration property.