| Characterization | Determination | Results and remarks | References |
| Elemental analysis | C, H, O, S, and N associated ratios | H/C, O/C, and N associated ratios are used to determine the degree of aromaticity and maturation | [56, 60, 61] | BET | Surface area, pore structures, average pore diameter, pore volume, and average pores of BC | 1057 m2g−1; macroporosity and microporosity; 5.2 nm; 0.24 mLg−1; 3.3 nm | [63, 125] | Boehm titration | Acidic and basic functional groups | Functional groups determined include carboxylic, lactonic, and phenolic | [45, 65] | FTIR/FTIS | Changes that occur in BC preparations as well as chemical functional groups present on the original BC | Changes include dehydration, pyrolysis, graphene nucleation, and finally carbonization; O–H (3600–3100 cm−1), C=C and C=O stretching (1740–1600 cm−1), C–O–C symmetric stretching (1097 cm−1), –COOMe (1400–1500 cm−1), and so on | [66–68] | CEC | Measure of the surface charge in soil or BC | At aging 278 to 518 mmolckg−1, 10.2 to 69.2 mmolckg−1, at neutral pH and 16.2 ± 6.0 and 21.0 ± 17.2 mmolckg−1 for BC produced at 400 and 600°C | [19, 69] |
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