3.2.2. Pore structure
Supplementary Fig. S1. and Table 2 show the pore diameter distributions
and surface areas of the feedstock and different biochar
samples. The mode, mean, and median pore diameters in the biochar
sample obtained at 500 C were smaller than those of biochar
samples obtained at 300 and 700 C. The specific pore volume of
the biochars ranged from 0.85 to 1.44 (cm3/g) and increased consistently
as pyrolysis temperature was increased from 300 to
700 C. Specific surface area of the biochar increased from 7.03
(m2 g1) at 300 C to 12.56 (m2 g1) at 500 C. However, biochar
surface area decreased substantially when pyrolysis temperature
was increased to 700 C. Chun et al. (2004) reported that the surface
area of a biochar produced at 700 C is lower than that of
one produced at 600 C, suggesting that fine-pore structure may
be damaged at 700 C.