Preparation Of Activated Carbon From Walnut Shell Wastes By Physical Activation In A Fluidized Bed Reactor

Human beings are faced with enormous pressures from energy lacking and environment pollution. The biomass energy is the most important kind of alternative energy in the future and its utilization is very low in our country. Most of the biomass wastes are directly burned or landfilled, it is harmful to the environment and waste of resources. If we can use these biomass wastes as raw material for the preparation of activated carbon, it will greatly optimize the development and utilization of energy in our country and solve a series of major issues such as the energy shortage, the lack of resources and environmental degradation. This is a research hotspot nowadays.Activated carbon is excellent adsorbent which has developed pore structure, high specific surface area and strong adsorption ability. It is widely used in environmental protection, agriculture, national defense, chemical industry, medicine, etc. As the rapid development of science and technology, there is a larger market demand for the activated carbon. In this thesis, the walnut shell wastes were used as raw materials, CO2as activation gas, activated carbon was prepared by physical activation method under fluidized state. Activation temperature and time were taken as main experimental parameters. The obtained activated carbons were further analyzed by N2adsorption at77K to determine specific surface area, pore volume to evaluate the characteristics of activated carbon prepared by this new process route.The results showed that the N2adsorption isotherms of activated carbons prepared at various activation temperature and time belong to the type I curve. The walnut shell activated carbon in this experiment has well developed microporous structure. Increases of activation temperature promote the formation of micro pores, and with the extension of activation time, the microporous structure of active carbon first increased and then decreased. Under the experimental conditions:activation temperature of900℃, activation time of2h, the activated carbons prepared by physical activation under fluidized state have maximum specific surface area of741.45m/g, and maximum D-R micropore volume of0.2448cm3/g. In addition, use CO2and N2mixed gas as activation gas can get activated carbon products with satisfactory pore structure, so under the condition of fluidization, preparation of activated carbon by physical activation method with the flue gas (main ingredients are CO2and N2) as activation gas is feasible.