Preparation Of Plant-based Activated Carbon Fiber Paper And Its Adsorption Performance For Toluene

As an important application form of activated carbon fiber(ACF),activated carbon fiber paper(ACFP)not only has the excellent adsorption performance of ACF,but also has the characteristics of low thickness,high stiffness,small pore between the fibers,and ease to function.It was widely used in air purification to realize the adsorption of harmful gases and the filtration of particulate pollutants.At present,there are relatively few studies on ACFP.And the prepared ACFP has disadvantages of poor mechanical properties and low specific surface area,and easily affected by environmental conditions,which seriously hinder the development and application of ACFP.This paper proposed a low-cost method to prepare ACFP with good mechanical properties,adsorption performance,chemical stability and high temperature resistance,and the relationship between the structure of ACFP and its adsorption performance was investigated.The aim of this paper is to provide a new idea for the preparation of ACFP and deepen the application of ACFP in the field of adsorption,which is helpful to the development and application of ACFP.The main research contents of this paper are as follows:(1)Plant-based ACFP was prepared from fibrillated bleach softwood fibers by wet forming and H3PO4 activation.The effect of fibrillation degree on ACFP structure was investigated.In the process of fibrillation revolution from 0 to 10kr,the specific surface area and total pore volume of ACFP increased gradually from 1751 m~2/g and 1.107 cm~3/g to1939 m~2/g and 1.155 cm~3/g.The main reason is that the slight damage to the cell wall promoted the penetration of H3PO4 into the interior of the fibers,forming more and aggregated phosphoric acid-polymer complexes,and the pores within the fibers developed during activation.In the process of fibrillation revolution from 10kr to 80kr,the specific surface area and total pore volume of ACFP decreased gradually from 1939 m~2/g and1.155 cm~3/g to 1196 m~2/g and 0.544 cm~3/g.This can be attributed to thinning of the cell wall and destruction of the cell cavity,resulting in a decrease in the content of the phosphate-polymer complexes.The phosphoric acid-polymer complexes were dispersed on the surface of the fibers,which caused the pores generated are concentrated on the surface of fiber.However,the strength of ACFP is relatively low.(2)The static and dynamic adsorption performance of commercial AC and ACFP were tested by designing adsorption experimental devices,and the adsorption behavior of ACFP was analyzed by mathematical models.The static adsorption experiments showed that the initial adsorption rate of ACFP was about 1.1?1.4 times that of cedarwood based AC.The dynamic adsorption experiment results indicated that the equilibrium adsorption capacity of ACFP was higher than that of coconut shell AC.ACFP10 has the largest equilibrium adsorption capacity of 460.6 mg/g.The adsorption capacity of ACFP for toluene was positively correlated with the specific surface area and pore volume of the mesopore.The mathematical model analysis declared that the Freundlich model is more accurate than the Langmuir model to describe the adsorption behavior of toluene by ACFP10.The adsorption process occurs on the non-uniform surface of ACFP10,and the adsorption heat has an exponential relationship with the surface coverage.The adsorption of toluene by ACFP10 is a spontaneous,exothermic process with reduced system disorder,and mainly controlled by physical adsorption.The increase in temperature is unfavorable to the adsorption process.The Thomas model and the Noon-Nelson model fit the experimental data well,which can predict the adsorption process of ACFP.(3)Carbon fiber reinforced activated carbon fiber paper(CACFP)was prepared from fibrillated bleach softwood fibers and carbon fibers by wet forming and H3PO4 activation.The effect of fibrillation degree and addition of carbon fibers on the structure and properties of CACFP was investigated.Results showed that CACFP possessed the specific surface area of1452?1076 m~2/g,the total pore volume of 0.496?1.019 cm~3/g,the toluene adsorption capacity of 200.8?271.6 mg/g.Carbon fibers play a connecting and reinforcing role in CACFP,which greatly improve the mechanical properties of CACFP.The maximum tensile strength of CACFP is 7.22 MPa,and it can be further processed into activated carbon fiber paper honeycomb.The penetrating adsorption capacity of CACFP0 remained more than 93.7%of the initial penetrating adsorption capacity after five cycles of regeneration.CACFP has high thermal stability that begins to decompose at about 420?in the air.CACFP shows a low spontaneous combustion tendency with the ignition point temperature of 513?and the apparent activation energy of 159.82 k J/mol.The CACFP prepared by this method shows good mechanical properties,which is favorable to the stable operation of the adsorption device and the recycling of adsorbent.It also can be used in environments with high temperature and humidity.