Porous properties of activated carbon produced from eucalyptus and wattle wood by carbon dioxide activation

This work focused on the preparation of activated carbon from eucalyptus and wattle wood by physical activation with CO2. The preparation process consisted of carbonization of the wood samples under the flow of N-2 at 400 degrees C and 60 min followed by activating the derived chars with CO2. The activation temperature was varied from 600 to 900 degrees C and activation time from 60 to 300 min, giving char burn-off in the range of 20-83%. The effect of CO2 concentration during activation was also studied. The porous properties of the resultant activated carbons were characterized based on the analysis of N2 adsorption isotherms at -196 degrees C. Experimental results showed that surface area, micropore volume and total pore volume of the activated carbon increased with the increase in activation time and temperature with temperature exerting the larger effect. The activated carbons produced from eucalyptus and wattle wood had the BET surface area ranging from 460 to 1,490 m(2)/g and 430 to 1,030 m(2)/g, respectively. The optimum activation conditions that gave the maximum in surface area and total pore volume occurred at 900 degrees C and 60 min for eucalyptus and 800 degrees C and 300 min for wattle wood. Under the conditions tested, the obtained activated carbons were dominated with micropore structure (similar to 80% of total pore volume).