| At present,the problem of particulate matter pollution in the steel industry is still very serious,which poses a major challenge to environmental governance.One of the key points of particulate matter emission control in the steel industry is the control of fine particles in the production process,especially the ferromagnetic particles discharged during the processing of raw materials.The traditional filter material dust removal and film coating technology can achieve efficient collection of fine particles.However,at present,fiber filter materials such as polyphenylene sulfide(PPS),polytetrafluoroethylene(PTFE),and aramid used for dust filtration in China are poor in temperature resistance,limited in output,and expensive,and basically depend on foreign imports.Large-scale promotion in the actual application process.The polyimide filter material has excellent high temperature resistance and good corrosion resistance.During the dust removal process,the particles have a very good deposition effect on the surface,and have great application potential in the field of high temperature dust-containing gas purification;On the one hand,polyimide filter media has limited ability to capture ferromagnetic particles with very small particle size.Therefore,attempts to develop new temperature-resistant and corrosion-resistant magnetic functional filter materials are of great significance for the removal of magnetic particles in the steel industry.However,the preparation of high-performance magnetic polyimide filter materials is still in a very challenging development stage.In this paper,a magnetic polyimide filter material was prepared by a coprecipitation method using a polyimide filter to support cobalt ferrite nanoparticles.In order to verify the excellent deposition load performance of cobalt ferrite on the surface of polyimide filter material,magnetic PTFE filter material,magnetic PPS filter material,magnetic glass fiber filter material and magnetic aramid filter material were also prepared by coprecipitation method.Scanning electron microscopy(SEM),X-ray diffraction(XRD),Fourier transform infrared spectroscopy(FTIR),VSM and other characterizations were used to analyze the nano-distribution of cobalt ferrite supported,the interaction mechanism between the surface of the filter material and cobalt ferrite nano-chloride,and ferric acid.Cobalt load uniformity,the difference in magnetic properties of the filter material;comparison of the performance of the magnetic polyimide filter material prepared by the coprecipitation method and the impregnation method,found that the impregnation method breaks through the maximum temperature of the polyimide filter material to a temperature of 260 ° C The magnetic polyimide filter material with higher crystallinity of cobalt ferrite is obtained,so that the impregnation method can achieve higher coercive force and residual magnetization when preparing the magnetic polyimide filter material;Based on the preparation of magnetic polyimide filter material,the effects of different preparation conditions on the hysteresis loop of magnetic polyimide filter material during the preparation of magnetic polyimide filter material were investigated.The non-magnetic polyimide was discussed.Filter material and magnetic polyacyl Amine difference filter in mechanical properties,heat resistance,acid and alkali resistance and the like,a non-magnetic test differences polyimide polyimide filter media and the magnetic fine particles trapped in the filter performance.The specific research work is as follows:Firstly,the magnetic polyimide filter loaded with cobalt ferrite was prepared by co-precipitation method.The magnetic PTFE filter material,magnetic PPS filter material,magnetic glass fiber filter material and magnetic fang were compared by SEM,XRD,FTIR and VSM.Four kinds of magnetic filter materials of reinforced filter materials,investigate the distribution characteristics,crystallinity,surface functional groups of magnetic ferrite nanoparticles loaded on polyimide filter materials,and explore the surface of polyimide filter material and cobalt ferrite nanometer.The interaction mechanism between particles,and the difference in residual magnetization and coercivity of magnetic polyimide filter,magnetic PTFE filter,magnetic PPS filter,magnetic glass filter,and magnetic aramid filter.The magnetic polyimide filter material prepared by the coprecipitation method is formed by nanoprecipitation of cobalt ferrite to the surface of the polyimide filter material in a water bath environment of 90 ° C.The baking temperature of the loaded nano-ferric acid cobalt is limited by the maximum temperature of the polyimide filter material,and the cobalt ferrite nano-crystal with better crystallinity needs to be calcined at a high temperature of 800 ° C or higher;the ferric acid can be separately prepared by the dipping method.Cobalt nano,and filter material loading,magnetic polyimide filter material prepared by comparative analysis of impregnation method and coprecipitation method.The results show that the polyimide filter material can provide a large surface area of adhesion,and the cobalt ferrite nanoparticles are more advantageous due to the strong polarity of the C=O double bond.Studies have shown that the impregnation method overcomes the limitation that the polyimide filter material can withstand high temperature,and obtains a magnetic polyimide filter material with higher nanocrystallinity of cobalt ferrite.Secondly,on the basis of the magnetic polyimide filter material prepared by the impregnation method,the pretreatment conditions of the filter material in the preparation process of the magnetic polyimide filter material,the stirring rotation number,the molar concentration of cobalt ferrite,and the reaction time on the ferric acid were investigated.The effect of cobalt on the loading of polyimide filter material indicates that the hydrochloric acid of the modified filter material will cause the carbonyl group on the surface of the filter fiber and the surface hydroxyl group of the ferric acid cobalt to form a p-л conjugate of OC=O due to residual H+.It should be impregnated with 10% hydrochloric acid to achieve the purpose of removing impurities on the surface of the filter material;the increase of the stirring number will increase the fluid turbulence and increase the probability of colloidal adsorption of cobalt ferrite nanoparticle and filter material,but when the number of revolutions exceeds 200r/min,The supported cobalt ferrite nano-nano will cause uneven loading on the surface of the filter material due to excessive rotation speed;the residual magnetization of the filter material will be 3.41 during the increase of the molar concentration of cobalt ferrite from 0.05 mol/L to 0.1 mol/L.The emu/g was increased to 3.73 emu/g;when the molar concentration of cobalt ferrite exceeded 0.1 mol/L,the nano-load of cobalt ferrite on the surface of the filter fiber was extremely uneven.As the stirring time increased from 0.5h to 2h,the residual magnetization of the magnetic filter material increased from 2.9emu/g to 3.95emu/g.When the stirring time increased to 2.5h,the residual magnetization of the magnetic filter material decreased slightly.From 3.95emu/g to 3.91emu/g.Finally,the magnetic polyimide filter material is placed in an ultra-high voltage,ultra-large capacity magnetizing power supply device EX 4000 V.After being energized,a magnetic field is generated to magnetize the magnetic ferrite on the surface of the filter material to obtain a magnetized polyimide filter material.Through the filter material reliability test and the experimental analysis of the fine particle filtration performance,the reliability performance difference between the non-magnetic polyimide filter material and the magnetic polyimide filter material is compared,and the non-magnetic polyimide is compared.The filter material,the modified polyimide filter material,the magnetic polyimide filter material,and the magnetically reinforced polyimide filter material have different filtration properties in the collection of fine particles.The results show that the magnetic polyimide filter material has no change in the warp and weft strength,the average temperature retention rate and the acid fracture resistance retention rate of the magnetic polyimide filter material compared with the non-magnetic polyimide filter material.5%,but non-magnetic and magnetic polyimide filter materials do not have good alkali corrosion resistance.Under the conditions of a filtration velocity of 1 m/min and an initial dust concentration of 70 mg/m3,an experimental test of static dust removal grading filtration efficiency was carried out.In the range where the aerosol fine particle diameter is less than 2 μm,the filtration efficiency of the magnetized polyimide filter material is improved compared with the non-magnetic,magnetic polyimide filter material as the particle size of the aerosol fine particle is smaller.20%.The resistance of the magnetic polyimide filter material is slightly increased due to the supported cobalt ferrite.When the filtration velocity is 1.5m/min,the resistance of the magnetic polyimide filter material is increased compared to the non-magnetic polyimide filter material.3Pa.As the filtration velocity increased from 0.5 m/min to 2.5 m/min,the resistance growth rate decreased from 100% to 29%. |
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