Fig. 5 shows the pore size distribution obtained for samples activated at 850 8C for 1, 2.5 and 3 h. The results obtained for the activation carried out at 900 8C are very similar to those at 850 8C.
The Barrett–Joyner–Halenda (BJH) method [35] was used to deduce the pore size distribution.
As observed for all the carbons,there is an important amount of pores of around 500A˚ , which is a result observed by other authors [20]. Moreover, for long activation periods, there is also an important amount of large pores of 1000A˚ .
This trend of increasing pore size with activation time has been observed by other authors [16].
It suggests that the activation process consists of micropore formation, followed by pore enlargement.