Study On Adsorption Characteristics Of Mercury By Mechanically Chemically Modified Fly Ash

Mercury and its compounds are toxic substances that can harm human health and the ecological environment,which have attracted widespread attention on a global scale.Due to the limitations of energy structure and technology,China has become the world's largest source of anthropogenic mercury emissions,and coal-fired power plants have ranked first in mercury emissions.Therefore,research on mercury pollution control in coal-fired power stations has become a hot topic.In recent years,research scholars have found that modified fly ash is a potential adsorbent for removing mercury from flue gas.In this paper,the mechanically coupled NaBr modification method is used to spray the corresponding concentration of NaBr solution into the ball mill fly ash for ball milling modification,which is close to the actual engineering application.Firstly,the paper uses the fixed bed adsorption system to investigate the mercury adsorption performance of mechanical force ball milling modified ash and mechanical force coupled NaBr modified ash under different working conditions.Secondly,the physicochemical properties of the two mechanically chemically modified ash were characterized by electronic scanning electron microscopy,infrared spectroscopy and X-ray electron spectroscopy.The research in this paper shows that the mechanical adsorption of ball ash can improve the adsorption capacity of fly ash to gaseous elemental mercury.The mechanical force and bromide modification method can be effectively combined.It is found that the mechanical coupling of NaBr modified ash can further improve the elemental mercury.The ability to remove is close to the effect of commercial activated carbon.At the same time,the modifier concentration,temperature and atmosphere are also closely related to the adsorption capacity of fly ash mercury.After mechanical chemical modification of the fly ash,the unburned carbon wrapped by the spherical glass body is exposed,the fly ash activity is improved,and the color is deepened.With particle size reduced and specific surface area increased,the probability of contact between mercury and fly ash surface active sites increase.At the same time,the mechanical chemistry also causes the chemical bonds on the fly ash surface and the valence of the elements to form active sites with dangling bonds.The surface of the new surface will also cause defects in the internal structure of the fly ash,making the fly ash in a highly unstable high energy state.The changes in physicochemical properties brought about by these mechanical chemistry are beneficial to the removal of gaseous elemental mercury by fly ash.However,over time,the adsorption capacity of modified fly ash to gaseous elemental mercury will be greatly attenuated over time.Therefore,shortening the preparation and placement time of the modified fly ash is necessary to remove flue gas mercury.