Table 3 Synthesis methods for iron-based biochar
Product of Fe-based biochar | Precursor material | Synthesis method | Synthesis process and condition | References |
|---|---|---|---|---|
Fe-loaded BC | FeCl3·6H2O, rape straw | Pyrolysis | FeSO4 and FeCl3 were mixed with biomass, aged for 12 h, and dried at 60 °C | |
nZVI-loaded BC | FeSO4·7H2O, NaBH4, herb residue | Co-reduction | Biomass was pyrolyzed at 400 °C for 2 h under N2, washed in 0.1 M HCl for 12 h, washed in water, and reduced by using NaBH4 under N2 | |
Fe3O4-loaded BC | FeCl2, FeCl3, corn stalk | Co-precipitation | Biomass was pyrolyzed at 400 °C for 2 h under N2, washed in HCl for 12 h, added with 5 M NaOH, Fe2+, and Fe3+, at 80 °C for 1 h | |
γ-Fe2O3-loaded BC | FeSO4·7H2O, banana peels | Hydrothermal | Biomass were mixed with FeSO4.7H2O, autoclaved at 180 °C for 6 h, and calcinated at 600 °C for 2 h under N2 | |
Fe-loaded BC | Fe, α-Fe2O3, Fe3O4, walnut shell, pinenut, coconut | Ball milling | Biomass was pyrolyzed at 500 °C for 1.5 h, mixed with Fe, α-Fe2O3, or Fe3O4 into 500 mL vacuum jar for ball milling process at 500 rpm for 6 h | |
nZVI-supported carbon (C–Fe0) | Fe(NO3)3·9H2O, carbon black | Carbothermal iron reduction | Fe(NO3)3 was impregnated onto carbon black at 600–800 °C for 3 h under Ar, | |
Fe-impregnated BC | FeCl3, maize straw, wheat straw, peanut shell | Pyrolysis | Biomass was mixed with FeCl3, stirred for 2 h, and pyrolyzed anaerobically at 350 and 700 °C. | |
Magnetic hematite-biochar composites (FOC), pyrite–biochar composites (FSC) | Pyrite powder, hematite powder, reed biochar | Co-pyrolysis | Biomass was pyrolyzed at 500 °C for 5 h under the oxygen-limited conditions, mixed with pyrite powder or hematite powder at the biomass:iron mass ratio of 1:3 in water matrix under sonication and stirring for 2 h, drying at 80 °C, and re-pyrolyzed at 600 °C for 6 h | |
Magnetite-impregnated BC | FeSO4·7H2O, FeCl3·6H2O, biochar | Co-precipitation | Biochar was mixed with FeSO4·7H2O and FeCl3·6H2O in water matrix, heated at 65 °C, cooled at 40 °C with continuous stirring, mixed with 5 M NaOH solution to pH 10–11, stirred for 1 h, rested overnight, filtered, and dried at 80 °C | |
Magnetic mesoporous carbon (MNPs@C) | FeCl2, FeCl3, activated carbon | Co-precipitation | Activated carbon was mixed with FeCl2, FeCl3, and NH3, stirred under N2 for 80 °C for 30 min, cooled to room temperature, rinsed with DI water, and dried at 70 °C for 6 h | |
Carbon-coated nZVI (Fe0@C) | Glucose, Fe3O4, | Combined hydrothermal carbonization and carbothermal reduction | Glucose was dissolved in water, mixed with Fe3O4, sonicated and stirred for 2 min, autoclaved at 120 °C for 10 h, cooled to room temperature, washed with ethanol, and pyrolyzed at 300, 500 and, 700 °C for 2 h each | |
Biochar-supported nano-scale zero-valent iron stabilized by carboxymethyl cellulose (BC-CMC-nZVI) | FeSO4·7H2O, NaBH4, wheat straw | Biomass was pyrolyzed at 600 °C for 2 h under limited oxygen condition, mixed with FeSO4·7H2O in N2-purged water matrix, mixed with CMC, mixed with NaBH4, purged with N2, aged for 12 h, and freeze-dried before use | ||
nZVI-loaded BC5 | FeSO4·7H2O, NaBH4, gasification product-BC | Reduction, deposition | FeSO4·7H2O was dissolved in N2-purged water, reduced by NaBH4, stirred for 20 min, deposited onto BC, aged at 25 °C for 3 h, filtered, washed with ethanol, and freeze-dried for 6 h | |
Magnetic carbonaceous adsorbent (MCA) | FeCl3·6H2O, corncob | Hydrothermal | Biomass was mixed with ZnCl2, autoclaved for 180 °C for 6 h to form carbonaceous precursor, mixed with FeCl3·6H2O, mixed with NaOH, autoclaved for 180 °C for 6 h, cooled to room temperature, washed with DI water, and dried in vacuum | |
Ball-milled BC (BM-BC) | Bagasse (BG), bamboo (BB) and hickory chips (HC) | Pyrolysis, ball milling | Biomasses were pyrolyzed at 300 450, and 600 °C for 1.5 h in N2 condition, and ball-milled at 300 rpm for 12 h | |
Ball milled Fe0-BC (BM-Fe0–BC) | Fe powder, cornstalk | Pyrolysis, ball milling | Biomasses were pyrolyzed at 300, 500, and 700 °C, mixed with Fe powder, purged with N2, ball milled at 400 rpm for 48 h | |
Fe, N co-doped biochar (Fe–N–BC) | FeSO4·7H2O, urea, wheat straw | Pyrolysis | FeSO4·7H2O, urea, ascorbic acid were dissolved in water, mixed with and biomass, autoclaved at 160 °C for 10 h, dried at 80 °C for 24 h, and calcinated at 800 °C for 1 h |
