Activated Carbon Fiber And Activated Carbon For Formaldehyde Adsorption Performance

With the use of various decoration materials in interior decoration,indoor formaldehyde pollution has gradually attracted widespread attention in modern society.Formaldehyde,as a carcinogenic and teratogenic substance identified by the World Health Organization,has seriously threaten human health.Therefore,it is extremely urgent to develop indoor air pollutant elimination and treatment technology.As the most widely used formaldehyde treatment method,the adsorption method has many advantages such as simple,efficient,low cost and reusability.Porous carbon materials such as activated carbon fiber and activated carbon are excellent adsorbent materials,which have the characteristics of large specific surface area,large pore volume,large number of micropores and stable performance.They are widely used in the adsorption treatment of formaldehyde and other gases.The pore structure and the influence of surface functional groups on formaldehyde adsorption have attracted wide attention.However,there are limited research on the pore size distribution and surface oxygen-containing functional groups of activated carbon fiber and activated carbon on formaldehyde adsorption.In this paper,a series of different activated carbon fibers(R-ACF,PAN-ACF,P-ACF)and high surface area activated carbon prepared by needle coke are studied.Activated carbon fibers and activated carbon are modified by nitric acid,hydrogen peroxide and air to increase the number of oxygen-containing functional groups on the surface of the material,and loading ethylenediamine to introduce nitrogen-containing functional groups.The prepared material was tested by a dynamic adsorption method in a fixed bed for the formaldehyde adsorption performance at room temperature.Studying factors of activated carbon fiber and activated carbon on formaldehyde adsorption,and providing certain technical support for the treatment on not only low concentration indoor formaldehyde pollution but also high concentration industrial formaldehyde.The main conclusions are as follows:(1)Three kinds of activated carbon fibers(R-ACF,PAN-ACF,P-ACF)were used to study the formaldehyde adsorption performance.It was found that ACF with a pore size from 0.9nm to 1.8nm had large formaldehyde adsorption capacity and good formaldehyde adsorption performance.The number of nitrogen-containing functional groups on the surface of activated carbon fibers decide the formaldehyde adsorption performance.(2)The formaldehyde breakthrough capacity was determined by the surface area and pore volume of ACF with pore size from 0.9nm to 1.8nm and the number of acidic oxygen-containing groups instead of oxygen content of ACF.The oxidative modification by nitric acid(65%)gave the highest adsorption capacity with the breakthrough capacity of 58.21mg/g,which was 2.5 times higher than the sample without treatment.The acidic oxygen-containing groups were rich with hydrophilic groups like C=O,C-OH which could react with formaldehyde and enhance the formaldehyde adsorption capacity.(3)Activated carbon samples with different surface area and pore volume were prepared by KOH activation of needle coke.Among them,AC7 has the largest surface area(3552 m2/g)and pore volume(2.12 cm3/g)and the longest formaldehyde breakthrough time.The breakthrough capacity is 8.57 mg/g.AC7 pretreated with nitric acid was modified by ethylenediamine impregnation.The modified AC7-HNO3-EDA sample had formaldehyde breakthrough time of 3.1h and breakthrough capacity of 24.91 mg/g.The nitric acid pretreatment produces a large amount of acidic oxygen-containing functional groups on the surface of the activated carbon.These functional groups not only influence the loading of ethylenediamine,but also have a good effect on formaldehyde adsorption.