2.3. Characterization methods
2.3.1. Surface area and pore size distribution
The specific surface area (SBET) and porosity of the samples were
determined by nitrogen adsorption–desorption isotherms measured
in a Micromeritics ASAP 2020 apparatus. Adsorption of N2
was performed at 77 K. Before analysis, the samples were degassed
under N2 flow at 350 C for 2 h in a vacuum at 27 Pa. The SBET of the
prepared activated carbons was estimated by the BET method
using N2 adsorption isotherm data. The micropore volumes were
calculated from the amount of N2 adsorbed at a relative pressure
of 0.1, and the mesopore volumes were calculated by subtracting
the amounts adsorbed at a relative pressure of 0.1 from those at
a relative pressure of 0.95 (Rodriguez-Reinoso et al., 1982). The
Barret–Joyner–Halenda (BJH) model was employed to calculate
the pore-size distribution of the samples.