Preparation And Adsorption Properties Of Phenolic-based Activated Carbon Fiber

Phenolic-based activated carbon fiber（PACF）is a new type of activated carbon fiber after polyacrylonitrile,viscose-based and pitch-based activated carbon fiber.Compared with the other three types of activated carbon fibers,the raw material of PACF-phenolic fiber（PF）is only composed of three elements,C,H,and O with a rigid three-dimensional network structure,which makes the PACF obtained by carbonization and activation treatment without pre-oxidation.There is no harmful gas emission.Therefore,PACF can be obtained with high carbon yield,rich microporous structure and large specific surface area.At this stage,research on PACF is relatively mature in Japan and can be put into industrial production.However,there is a serious technological blockade against China.Although a few laboratories in China have conducted exploratory research on the preparation process of PACF,research on PACF is in its infancy on the whole.Little is known about the process control methods of fiber specific surface area,pore size,etc.,and the adsorption research is not systematic enough.The relationship between process regulation,fiber structure and adsorption performance has not been established.In this paper,the effects of carbonization temperature and time on the structure and adsorption performance of phenolic carbon fibers（PCF）were first investigated.Then,the phenolic activated carbon fibers HPACF and WPACF were prepared by KOH chemical activation method and water vapor physical activation method,respectively.The effects of activation temperature,alkali-carbon ratio or water vapor flow rate on the structure and adsorption properties of the product were investigated.Three aspects of process regulation,fiber structure and adsorption capacity were established,and the process parameters for preparing high adsorption performance PACF were obtained.It is found that the carbon content of the fiber gradually increased,the pore volume gradually increased,and the specific surface area first increased and then decreased slightly with the increase of carbonization temperature or the prolongation of carbonization time.PCF-700carbonized at 700℃for 1h has a specific surface area of 557m~2/g and a pore volume of 0.24m L/g.Such conditions can effectively shorten the carbonization process while ensuring a relatively high specific surface area,therefore it is beneficial for actual production.It is found that it is beneficial to the development of pore structure to a certain extent with the increase of activation temperature,alkali-carbon ratio or water vapor flow rate.The KOH chemical activation method is more favorable for the development of the pore structure at a lower activation temperature of 700°C.At this temperature,HPACF-700 prepared with an alkali-carbon ratio of 4 has the largest specific surface area of 856m~2/g and the pore volume can reach 0.37m L/g.The pore size ratio of 0.8-1.4nm is significantly improved.At a higher activation temperature of 900°C,the water vapor physical activation method has obvious advantages.At this temperature,WPACF-900 prepared with a water vapor flow rate of 10g/min has the largest specific surface area of 1205m~2/g,and the pore volume can reach 0.50m L/g.The 0.7-1.4nm aperture ratio is greatly improved.The adsorption capacity of copper sulfate,p-phenylenediamine and methylene blue is significantly higher than that of HPACF-700.In general,phenolic-based activated carbon fibers with larger specific surface area and better adsorption capacity can be prepared by the physical activation method.