The effects of microwave radiation time on the activation are
demonstrated in Fig. 2; the phosphoric acid/carbon ratio was 1:1
and the microwave power was 350 W. As can be seen, the activation
time had great influence on the development of pore structure.
At the initial stage, both micropores and mesopores increased significantly,
indicating that the pores were formed and enlarged
simultaneously in this stage. With activation time going on, the
increase of micropores gradually became slow and a slight drop
was observed at 30 min, while the mesopore surface and volume
went up steadily in the whole process. This phenomenon implied
that the formation of new pores became less significant as the activation
proceeded, and the micropores were continuously widened
into larger ones, resulting in the increase of mesopores. Another
possible reason for the loss of micropores was that they might also
be destroyed after long time exposure to the microwave radiation.A
similar tendency has been observed in the preparation of activated
carbon from rice husk (Kennedy et al., 2004).
The effects of microwave radiation time on the activation aredemonstrated in Fig. 2; the phosphoric acid/carbon ratio was 1:1and the microwave power was 350 W. As can be seen, the activationtime had great influence on the development of pore structure.At the initial stage, both micropores and mesopores increased significantly,indicating that the pores were formed and enlargedsimultaneously in this stage. With activation time going on, theincrease of micropores gradually became slow and a slight dropwas observed at 30 min, while the mesopore surface and volumewent up steadily in the whole process. This phenomenon impliedthat the formation of new pores became less significant as the activationproceeded, and the micropores were continuously widenedinto larger ones, resulting in the increase of mesopores. Anotherpossible reason for the loss of micropores was that they might alsobe destroyed after long time exposure to the microwave radiation.Asimilar tendency has been observed in the preparation of activatedcarbon from rice husk (Kennedy et al., 2004).
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