2.4.3. N2 sorption analysis
Gas sorption isotherms were obtained using an ASAP 2020 from
Micromeritics, operated at 196 C. Prior to analysis, the samples
were degassed under vacuum at 90 C for 12 h. The specific surface
area (SSA) was calculated using the multipoint Brunauer–Emmett–
Teller (BET) method (Brunauer et al.,1938) for adsorption values in
the relative pressure range between 0.05 and 0.3, while the pore
size distribution was calculated based on the density functional
theory (DFT) method using the model for N2 at 196 C. The total
pore volume was obtained from single point adsorption at a
relative pressure P/P0 1. These calculations, including calculations
of the errors of the SSA values, were all performed using the
ASAP 2020 (Micromeritics) software.