Arundo donax cane as a precursor for activated carbons preparation by phosphoric acid activation

Canes from Arundo donax, a herbaceous rapid-growing plant, were used as precursor for activated carbon preparation by phosphoric acid activation under a self-generated atmosphere. The influence of the carbonization temperature in the range 400-550 degreesC and of the weight ratio phosphoric acid to precursor (R = 1.5-2.5) on the developed porous structure of the resulting carbons was studied for 1 g of carbonization time. Surface properties of the activated carbons were dependent on a combined effect of the conditions employed. Carbons developed either with R = 1.5 over the range 400-500 degreesC, or with R = 2 at 500 degreesC exhibited surface areas of around 1100 m(2)/g, the latter conditions promoting a larger pore volume and enhanced mesoporous character. For both ratios, temperature above 500 degreesC led to reduction in porosity development. A similar effect was found for the highest ratio (R = 2.5) and 500 degreesC. The influence of carrying out the carbonization either for times shorter than 1 h or under flowing N-2 was also examined at selected conditions (R = 2, 500 degreesC). Shorter times induced increase in the surface area (similar to1300 m(2)/g), yielding carbons with smaller mean pore radius. Activated carbons obtained under flowing N-2 possessed predominant microporous structures and larger ash contents than the samples derived in the self-generated atmosphere. (C) 2002 Elsevier Science Ltd. All rights reserved.