Experimental Study On Adsorption Of Nitrogen Oxides By Modified Activated Carbon Fibers

There are many kinds of pollutants in the air,and nitrogen oxide is one of them.For people who stay indoors for a long time,if the concentration of nitrogen oxides in the air is too high,it will cause great harm to their health.Researchers have conducted some in-depth studies on the adsorption of nitrogen oxides by activated carbon fibers and the modification of activated carbon fibers to improve the adsorption capacity of activated carbon fibers.But researchers have done relatively little to quantify the effects of various environmental factors on nox.The main purpose of this study is to realize that the outdoor air has been optimized before entering the indoor air through the air conditioning system,which is of great significance for the removal of nitrogen oxides in the air.In this paper,on the basis of fully summarizing the relevant research content and results of absorption,a set of starting circulation system was designed and built,and activated carbon fiber adsorption filter was made.The pollution gas source is directly from the outdoor.BET,SEM,XPS and ft-ir were used to characterize the activated carbon fibers.On this basis,with nitrogen oxides in outdoor air as the target pollutants,a series of adsorption reaction experiments were carried out in the self-built open circulation system under different experimental conditions,and the rules were obtained.Activated carbon fiber?acf?was modified and adsorbed on nitrogen oxides in an open cycle system to investigate its adsorption efficiency.By changing the initial concentration of nitrogen oxides in the outdoor air,the wind speed at the adsorption filter,and the temperature,the influence of the above environmental factors on the adsorption effect was investigated,and the resistance values before and after the activated carbon fiber filter were measured at different wind speeds.Finally,the activated carbon fiber was desorbed to investigate its reusability.The conclusions are as follows:?1?According to the BET characterization results of activated carbon fibers before and after modification,the adsorption and desorption isotherms of activated carbon fibers before and after modification were all of type I,as shown by the N₂ isothermal adsorption and desorption map.By comparing the specific surface and pore structure parameters of activated carbon fiber before and after modification,it is found that the specific surface area of activated carbon fiber increases,pore volume decreases and pore diameter increases.The adsorption capacity of the modified activated carbon fiber was higher than that before modification.?2?According to the SEM characterization results of activated carbon fibers before and after modification,the surface of the unmodified activated carbon fibers is smooth and orderly with no foreign matters attached to the surface.After the modification of activated carbon fiber nitrate,the surface gully and uplift ports increased,but after the adsorption experiment,the surface gully of modified activated carbon fiber decreased obviously,and the surface changed a lot compared with before the experiment.?3?According to the XPS diagram of activated carbon fiber before and after modification,the modified activated carbon fiber surface simultaneously introducedeffectiveoxygen-containingfunctionalgroupsand nitrogen-containing functional groups,which enhanced the surface polarity of ACF,so as to adsorb NO and NO2 more effectively and improve the ability of ACF surface to absorb nitrogen oxides.?4?The hydroxyl peak of activated carbon fibers modified by nitric acid was significantly enhanced through the ft-ir diagram of activated carbon fibers before and after modification,and a large amount of hydroxyl groups were introduced into the surface of activated carbon fibers through modification.?5?The activated carbon fiber was modified by impregnation method,and nitrogen oxide adsorption experiment was conducted on the activated carbon fiber before and after modification in the open system.The experimental results showed that the adsorption effect of n-acf was better than that of ACF,and the adsorption trend of activated carbon fibers was generally consistent before and after modification under the same adsorption conditions.?6?At a specific temperature and wind speed,the adsorption efficiency of nitrogen oxides by activated carbon fibers before and after modification decreased with the increase of initial concentration of nitrogen oxides in outdoor air;In a certain range of initial concentration of nitrogen oxides and specific wind speed,the denitrification rate first increases and then decreases with the increase of temperature.In a certain initial concentration of nitrogen oxides and a certain temperature range,the denitrification rate tends to increase first and then decrease with the increase of wind speed.?7?During the adsorption experiment,the resistance values of activated carbon fibers before and after modification decreased with the increase of wind speed.At the wind speed of 2.5m/s,the resistance value was about 5Pa,and the resistance value was small.Therefore,it can be applied to the air conditioning system.?8?The adsorption rate of the modified activated carbon fiber is about 60%under better conditions.After 5 times of water elution and desorption,the denitrification rate only decreased by 2.35%on average,which showed good reusability.The experimental results show that it can be applied to the air conditioning system.