| In recent years,with the continuous increase of indoor environmental pollutants,formaldehyde pollutants have become a major problem endangering people's health.The removal and purification of it has been widely concerned by scholars at home and abroad.Current situation at present,the traditional adsorption technology for formaldehyde adsorption purification effect is not good,because of the formaldehyde is small molecular gas,physical adsorption is hard to get its adsorption,and adsorption time is short,easy to desorb,resulting in secondary pollution.Although chemical adsorption removal of formaldehyde adsorption effect is better than of physical adsorption,but in many cases cant'regeneration,the high cost of application is widely used,is also the bottleneck of restricting its development.At present,the most widely studied is the use of nano-porous materials for formaldehyde adsorption,so this subject will prepare a physical and chemical double-effect material for formaldehyde adsorption performance research.By fully exploring the morphology of double material signs and in the different factors affecting the adsorption effect,accurate grasp of the performance of the material,and guarantee the indoor air quality and people's health,is advantageous to the widely application in the field of air purification,for the production of scientific research has important practical significance.This subject mainly studies the mechanism of indoor formaldehyde degradation by nano-porous substrate loaded with chemical adsorption.Firstly materials and adsorbents were selected,and potassium permanganate was loaded on activated carbon.A double-effect material?loading rate was 5,10 and 20%?was prepared by mixing ratio,ultrasonic oscillation impregnation and drying treatment.The modified material was analyzed and compared by SEM,SEM and specific surface area and porosity analyzer.The internal and external factors affecting the formaldehyde removal efficiency of modified activated carbon materials were further explored.According to the international standards of ISO and ASHRAE,a single channel filter material performance test system was built,which can meet the control of formaldehyde production concentration?0-5 ppm?and temperature and humidity?20-80%RH at 25 C stability?.The effects of different loading rates?5,10 and 20%?,different space velocities(255 min-1,510 min-1 and 1020 min-1)and different relative humidity?20,50 and80%?on formaldehyde adsorption were studied.The purification and effect of modified activated carbon under different conditions were compared.In this study,the following findings were found:?1?Scanning electron microscopy?SEM?showed that before loading,the surface of the modified activated carbon was relatively smooth,pore size distribution was obvious,and the shape of the modified activated carbon was mainly elliptical.After modification with potassium permanganate,the surface of activated carbon was corroded relatively rough,and the shape of activated carbon was uniformly and compactly accumulated in the form of massive corals.The intersecting pore was more abundant and obvious.The morphology and structure of activated carbon changed greatly before and after modification.?2?Through the analysis and measurement of specific surface area and porosity,it was found that the BET specific surface area,total pore volume and average pore size of the modified activated carbon decreased,while the macropore volume remained basically unchanged,and the micropore volume and mesoporous volume showed a downward trend,which indicated that the loaded potassium permanganate substances were basically distributed in the microporous and mesoporous structure.?3?The removal efficiency of unloaded activated carbon is the worst.The removal efficiency of impregnated loaded modified activated carbon is improved.The modified activated carbon with 20%loading rate has the highest adsorption capacity and the lowest adsorption decline rate,which improves the adsorption efficiency and prolongs the adsorption penetration time.?4?Relative humidity has a significant effect on the removal of formaldehyde by modified activated carbon.With the increasing of relative humidity,the removal performance of modified material becomes worse gradually.The removal effect is the best when the relative humidity is 20%,and the worst when the relative humidity is 80%.The reason is that the water molecules and formaldehyde molecules in the gas have competitive adsorption on the surface of activated carbon.?5?Comparing the working conditions of different space velocities,when the space velocity is 1020min-1,the adsorption capacity is the lowest,the adsorption effect is the worst,and the penetration time is the shortest;when the space velocity is 255 min-1,the adsorption capacity is the best and the purification effect is the longest.Because the higher the adsorption bed,the longer the gas passes through,the lower the space velocity.?6?From the point of view of economic performance,the modified activated carbon materials with inactivation can be re-loaded for more than two times,and formaldehyde can be removed by adsorption.Compared with the previous one,the adsorption effect is not much different,the adsorption duration is relatively stable,the adsorption capacity is the lowest,the adsorption effect is the worst and the penetration time is the shortest after the second load.This topic through the method of combining the theoretical analysis and experimental research,aimed at the preparation of a double-effect of adsorption material used in the purification of indoor air formaldehyde.In-depth study is made on the effect of different loading rates,relative humidity,space velocities of the material,and the use of multiple loads on its adsorption effect from the point of view of green environmental protection in the process of purifying the filter material.The optimal experimental conditions are obtained,which provides a scientific basis for the application of dual-effect materials in the field of practical purification in the future. |
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