Preparation And Characterization Of The High Decolorization Activated Carbon From Bamboo

The activated carbon is a kind of sorbent with abundant porosity, high adsorption capability and high surface activity. It is made from carbon raw material and can be produced through physical or chemical activation methods. The activated carbon is applied extensively in chemical industry and generally the application related to the activated carbon needs large amount of activated carbon. Since the application demand of activated carbon becomes higher, the low-priced raw material and the new activation method to prepare activated carbon with better capability become important. The bamboo can be used as the raw material because of its short growth period and abundant resource in Southern China.The activated carbon is prepared from bamboo sawdust by two-step process method in this thesis. The activated carbon is characterized by methylene blue number, iodine number and caramel decolorization. The optimum preparation conditions such as impregnation time, activation temperature, impregnation ratio and activation time are obtained by detailed experiments. Meanwhile the other properties, such as specific surface area, internal porosity, pore size distribution, functional groups and adsorbing isothermal, are studied in detail by the experiment. The activated carbons are prepared using different activating agents. The optimum preparation conditions corresponding to H₃P0₄ and ZnCl₂ used as activating agent are-H₃P0₄/bamboo sawdust 150%, the impregnation ratio of ZnCl₂/the carbonized material 150%, the activation temperature at first stage 500℃and at second stage 400°C, and the total activation time 60 min. The optimum preparation conditions corresponding to H₃PO₄ and KOH used as activating agent are H₃P0₄/bamboo sawdust 100%, the impregnation ratio of KOH /the carbonized material 300%, the activation temperature at first stage 400℃with activation time 30 min, at second stage 700℃with activation time 15 min. The activated carbon produced by H₃P0₄/ KOH activation method has big porosity and specific surface area, and its adsorption capability to dye wastewater is better. The activated carbon produced by H₃P0₄/ZnCl₂ activation method has abundant micropores and mesopores, and its caramel decolorization capability is better than the former.To the two kinds of complex preparation methods, both haverich surface function groups and good fading adsorption capability to dye wastewater. The equilibrium time of H₃P0₄/ZnCl₂ and H₃P0₄/K0H sample in the acidic pinkish red dye wastewater is 250 min and 100 min respectively. When the equilibrium concentration is 140 mg/L, the saturated adsorption quantity is 100 mg/g and 172 mg/g respectively. The experimental data on the adsorption equilibrium isotherms of both samples can be fitted well by the Freundlich isotherm equation.The equilibrium time in the alkalinity pinkish red wastewater are 500min and 400 min respectively corresponding to different activating agents: H₃P0₄/ZnCl₂ and H₃P0₄/K0H. When the equilibrium concentration is 100 mg/L, the saturated adsorption quantity is 180 mg/g and 280 mg/g respectively. The experimental data on the adsorption equilibrium isotherms corresponding to both samples also can be fitted well by the Langmuir isotherm equation.In general, for the activated carbon made from bamboo, two-step preparation method, technics and adsorption capability are better than one-step activation method through the study in this thesis.