The Chemical Activation Mechanism Research On Preparation Of Activated Carbon From Aspen Wood

Mankind faces great pressures from energy lacking and environment impact. Biomass is a most important kind of alternative energy in the future. Especially the plant resources, with largest reserves of renewable resources, are cheap and easy to obtain. Waste biomass burning leads to environmental pollution, but as raw material to prepare activated carbon will greatly extend the biomass effective use. This is also a research hotspot nowadays.Activated carbon, a good adsorbent having micropores well developed, specific surface area, high adsorption ability, is widely used in environmental protection, industrial production, agriculture, national defense chemical industry, etc. Along with the rapid development of science and technology, there is larger market demand for activated carbon. In this thesis, the plant biomass was used as raw materials, KOH as chemical agent, activated carbon was prepared under nitrogen environment. Activation temperature and time, and KOH/cottonwood mixing ratio (w/w) were taken as main experimental parameters to analyze the preparation mechanism of activated carbon based on cottonwood. The experiments were performed in thermogravimetric analyzer to know the cottonwood pyrolysis characteristics. The derived activated carbons were further analyzed by N2 adsorption at 77 K to determine specific surface area, pore volume, etc.The results showed that pyrolysis of the poplar material completed up to 550?, and ignition loss reaction happened above 700?. In the range between 550? and 700?, cottonwood can be activated for preparation of activated carbon. N2 adsorption isotherms of activated carbons prepared at various activation temperature and time and mass ratio of KOH to cottonwood belong to the type I adsorption isotherm. Increases of activation temperature and time, and mass ratio of KOH promote the formation of micro pores. The cottonwood based activated carbons by KOH chemical activation have maximum specific surface area of 1551.68m2/g, and D-R micropore volume of as high as 0.5186 cm3/g, corresponding to the experimental conditions:pyrolysis temperature of 700"C, activation time of 30 min, and KOH mass ratio of 3. In addition, micropores are dominant in the pore distribution of activated carbons, and the proportion of mesopores in activated carbon increases with activation temperature and activation time and the mass ratio of KOH.