Preparation And Activation Enhancement Of Polyethylene Glycol 2000 Modified RF Carbon Aerogels

Carbon aerogel is a kind of three-dimensional network nanometer material with high specific surface area,high porosity,low density and adjustable pore size distribution.It is widely used in fields of chemical engineering,environmental management,drug release,supercapacitors,catalysts and carriers,thermal materials.Conventional RF carbon aerogels are prepared from resorcinol and formaldehyde as raw materials under the action of a basic catalyst.They are prepared by sol-gel,pickling,solvent replacement,drying,and high temperature carbonization.The prepared carbon aerogels have small density and relatively concentrated pore size distribution.However,the production cost is high and the preparation cycle is long,which seriously restricts its application.In view of this problem,this paper discussed the use of polyethylene glycol 2000 as a pore-forming agent mixed into RF organic aerogels to prepare new organic carbon aerogels.The main research content in this paper is as follows:Firstly,resorcinol,formaldehyde and polyethylene glycol 2000 were used as raw materials.The polyethylene glycol modified carbon aerogels were formed by the sol-gel process,solvent replacement,atmospheric pressure drying,and carbonization under the N₂ atmosphere at 850°C.The effects of different catalyst content and porogen content on gel color,density,shrinkage,and the adsorption of iodine and methylene blue were studied.The effects of different preparation conditions on pore structure and pore size distribution of carbon aerogels were studied.The results show that polyethylene glycol 2000 has a pore-forming effect on RF carbon aerogels,and the specific surface area of carbon aerogels increases from 522m²/g to 705 m²/g.The average pore diameter can be used to judge that the formed pores are mainly mesoporous.However,the content of polyethylene glycol 2000 reaches a certain level,and it is not easy to form a uniform organic aerogel.Secondly,the prepared carbon aerogels were activated and upgraded.The adsorption values of iodine and methylene blue were taken as the target values.The effects of KOH solution concentration,ratio of liquid to solid,activation temperature and activation time on the carbon aerogel were examined.The results showed that the unmodified RF carbon aerogels had the highest iodine adsorption valuesand methylene blue when the ratio of liquid to solid was 4:1,the activation temperature was 800°C,the activation time was 60 min,and the KOH concentration was 1.4mol/L,respectively1256.27 mg/g and 225.07 mg/g;Modified RF carbon aerogel,when the ratio of liquid to material is 4:1,activation temperature is 750°C,activation time is 60 min,and KOH concentration is 1.4 mol/L,the values were 1695.28 mg/g and 343.07 mg/g,respectively.Finally,the properties of the prepared carbon aerogels were characterized by infrared,TG,SEM and BET.The results show that polyethylene glycol 2000 has a pore-forming effect on RF carbon aerogels,and the pores are mainly mesoporous;polyethylene glycol 2000 can reduce the activation temperature appropriately in the preparation of carbon aerogel by KOH solution activation.