Preparation Of Modified Sepiolite And Its Adsorption Performance Of Ammonia Gas

At present,with the continuous improvement of the level of industrialization and urbanization,the environmental problems caused by odor pollution are becoming more and more serious,which not only affects people’s living environment,but also brings a series of physical and mental health problems.Therefore,the treatment of odor pollution has gradually attracted people’s attention.Ammonia（NH₃）plays a major role in odor pollution,and long-term exposure to NH₃-polluted air will cause great damage to human body,which makes research on an efficient and economic NH₃ adsorbent become a hot topic at present.In this paper,sepiolite,which is abundant in xiangtan,is used as raw material to prepare NH₃ adsorbent by modifying it.On this basis,the adsorption capacity of NH₃ is studied.In this paper,two different modification methods were used to prepare acid-modified sepiolite adsorbent and metal chloride impregnation modified sepiolite adsorbent.Then,SEM,XRD,FTIR,BET and other methods were used to analyze and compare the results.Comparing the adsorption properties of sepiolite to NH₃ before and after modification,the variation of ammonia adsorption properties under different modification conditions was studied.The adsorption behavior of sepiolite modified by different acids was investigated by using NH₃ as adsorbent.The results showed that sepiolite was modified with 2 mol/L HCl at 70℃for 10 h,and the maximum specific surface area reached 213 m²/g.NH₃ adsorption capacity increased from 0.556 mmol/g to 1.22 mmol/g.Subsequently,the adsorption effect of several different metal chlorides（Fe Cl₃,Cu Cl₂,Zn Cl₂）modified sepiolite materials on NH₃ was investigated.The effects of impregnation type,adsorption temperature and other factors on adsorption performance were investigated.The results show that the adsorption of NH₃ by 20%Cu Cl₂/SEP is the best in the modification of sepiolite with different metal chlorides,and the adsorption capacity is up to 4.541 mmol/g at 35℃.The adsorption effect of the modified materials at different temperatures（35℃,45℃,55℃）was investigated.The results showed that the adsorption effect of the adsorbent on NH₃ gradually deteriorated with the increase of temperature.Two typical Langmuir and Freundlich isotherm models were used to fit the adsorption data of 20%Cu Cl₂ impregnated sepiolite.It was found that the adsorption isotherm of 20%Cu Cl₂ impregnated sepiolite was more consistent with Langmuir model.In order to compare the preparation cost of NH₃adsorbent,this paper also proposed a relatively simple price evaluation scheme,examined the price of adsorbent adsorption unit mole of NH₃,and found that the NH₃adsorbent prepared in this experiment has the lowest preparation cost.In addition,this paper also analyzed the adsorption mechanism of ammonia by two adsorbents prepared by different modification methods,and found that the adsorption of NH₃ by acid-modified sepiolite adsorbent is mainly physical adsorption.As for the metal chloride impregnated sepiolite adsorbent,its adsorption of NH₃combines physical adsorption and chemical adsorption.The principle of chemical adsorption is that metal chloride and ammonia form complex to cover the surface of the adsorbent.