Development of Activated Carbon Blended with Waste Bark

Abstract

Activated carbons were prepared from woody pellets, which were mixed with several percentages of waste bark and wood of typical conifer trees. Specific surface areas of activated carbons from several percentages of waste bark were measured in yields between 9-17%. Specific surface areas of activated carbons of 0wt% bark (100wt% wood) and 100wt% bark (0wt% wood) were 900-1,200m²/g and 740-780m²/g, respectively. Waste bark seemed to be inferior to wood as a precursor of activated carbon. However, specific surface area of 25wt% bark (75wt% wood) was 1,230-1,430m²/g, and it was the largest, even though mixed with bark. X-ray fluorescence of the ashes which were prepared from waste bark were measured, and calcium was detected as a main element, whose content was over 70wt%. Raw materials, char and activated carbons were analyzed by X-ray powder diffraction measurement. Calcium oxalate was detected in raw materials, and calcium carbonate and calcium oxide were detected in char and activated carbons, respectively, which were produced by pyrolysis from precursor during carbonization process and activation process. During activation, calcium carbonate, which was in char, was decomposed to calcium oxide and carbon dioxide, and it seems they participated in development of specific surface area of activated carbons mixed with bark. Adsorption performances of activated carbon of 25wt% bark for toluene, isopropyl alcohol and acetaldehyde were compared with those of the coconut shell based activated carbon, and revealed to be better than them.