Effects of Alkali/Char Ratio and Activation Temperature on Ultramicropores of Rice Husk Active Carbon

Porous carbons were prepared by KOH activation of rice husk char at alkali/char ratios of 0.6︰1 to 3︰1 and activation temperatures from 640℃ to 780 ℃.The obtained porous carbons were characterized using N 2 adsorption and desorption technique, CO 2 adsorption, TG-FTIR analyses.The results indicate that the ultramicropore size of the prepared porous carbons is mostly in the range of 0.42-0.70nm.As the alkali/char ratio increases, the volume of ultramicropores first rises and then diminishes, whereas the volume of ultramicropores tends to decrease monotonously with the increase of activation temperature.A microporous carbon with ultramicropore volume of 0.149 mL/g, ultramicropore fraction of 36.3%, pore volume of 0.411 mL/g, and specific surface area of 774 m 2 /g, can be produced by activation at 640℃ at the alkali/char ratio of 1︰1.The ultramicropore volume of the porous carbons and their CO 2 uptake at 10 4 Pa display a strong linear relationship.