Study On Filtration Performance And Mechanism Of Carbon Nanotube Composite Filter For Oil Particle

The suspended oil particulate matter in the air is an important pollutant harmed health,which is generated from cooking activity and industry process.Due to simple operation and low energy consumption,filtration technology is widely used in the field of oil fume and oil mist treatment.However,the studies on filtration technology applied to remove oil mist and fume focus on traditional materials at present.Traditional materials have some disadvantages such as high increase rate of pressure drop and low filtration efficiency.In this paper,the synthesis of composite filter based on high-precision traditional filter base on nano-fiber materials and lipophilicity materials.CNTs composite filter is designed and synthesized on the framework of macroporous metal foam.The characteristics and structure of composite filter are tested and analyzed,and the filtration performance of composite filter is systematically analyzed and studied.With the help of finite element software,the wetting behavior of liquid particles on the filter is simulated.The photocatalyst was loaded on CNTs composite filter to further reduce the energy consumption of the composite filter.Firstly,the preparation of modified nickel foam,carbon nanotube composite filter and photocatalyst/carbon nanotube composite filter were introduced.The growth mechanism of carbon nanotube composite filter was obtained by scanning electron microscopy.The content of carbon nanotubes in composite filter is about 15.51%,and the composite filter has good thermal stability.Compared with the pristine metal foam substrate,the specific surface area of CNTs composite filter increased,and the pore size distribution range decreased from several hundred microns to less than 1?m.The composite filter has excellent lipophilicity and hydrophobicity.After loading photocatalyst,the specific surface of the composite filter is further increased and the lipophilicity property is also improved.The filtration performance of the composite filter were studied by experimental method.The results show that the composite filter has lower increase rate of pressure drop compared with the traditional glass fiber filter.In the process of dynamic filtration,the pressure drop does not show exponential increase.The low increase rate of pressure drop between the saturated state and the initial state is an important advantage of the composite filter.The filtration precision of compound filter reaches HEPA.It is found that the surface layer of carbon nanotubes in the composite filter can improve the filter performance.In addition,the filtration speed can improve the filtration pressure drop and efficiency.Particle concentration has little effect on the filtration performance,and the higher the concentration is,the faster the filter reaches saturation state.The Surface Evolver software was used to simulate the attachment morphology and wetting behavior of liquid particles on single fiber and multi-fiber.Fiber surface properties and droplet volume have great influence on droplet attachment morphology and wetting behavior.The mechanism of liquid bridge migration and evolation to liquid film was revealed by simulating the wetting behavior of cross fibers.In addition,the results show that the critical interval of fibers is the key factor for the fracture of the liquid bridge,and the fracture of the liquid bridge can reduce the probability of film formation and the pressure drop of the filter.The dynamic filtration model was established based on the experimental data,which proved that there was no liquid membrane or liquid bridge in the filtration process for the composite filter.The results show that the adjustment of drainage in the filtration process will occur spontaneously according to the change of particle concentration and particle size distribution and the pressure drop of the composite filter at saturated state will not be affected.Under the same packing density of composite filter,the more dispersed the fiber,the better the filtration performance.It was found that the loaded photocatalyst has no negative effect on the filtration performance of the composite filter,and the filtration efficiency of the composite filter was higher than that of the traditional high-efficiency glass fiber filter HEPA-H13.The change of concentration of particulate matter in composite filter at different filtration stages influence on degradation rates of oleic acid,and the degradation curves presents different reaction levels.The reaction temperature obviously improved the degradation rate and amount of oleic acid.Light intensity promoted the degradation rate and amount of oleic acid.Finally,the reaction kinetics model was used to predict the generation of CO₂ and refractory intermediates in photocatalytic reaction.