Table 8.
Summary of various engineered/modified biochars and their immobilization efficiency for organic contaminants in the soil system.
| Biochar type | Pyrolysis temperature (°C) | Modification agents/technique | Application rate | Organic contaminants | Immobilization performances | Main findings | References |
|---|---|---|---|---|---|---|---|
| Maize stalk | 700 | Sulfur-nZVI | 0.25 and 1.5% | Nitrobenzene | 0.72 mg g−1 | The mass ratio of sulfur-nZVI and biochar was 3:1, the application rate was 0.5%, and 98% nitrobenzene removal was attained within 24 h | 152 |
| Rice husk | 700 | Rhamnolipid | 2% | Petroleum | 30 mg kg−1 | The removal amount of total petroleum hydrocarbons for planted and un-planted soil and planted soil with rhamnolipid-treated biochar application were 8%, 19%, and 35%, respectively | 153 |
| Maize stalk | 600 | Acinetobacter-loaded and Ferric nitrate nonahydrate | 0.1% | Atrazine | 20 mg kg−1 | Almost all the atrazine was degraded after treatment of engineered biochar, mainly owing to the Fe-loading boosted the microbial degradation capability as an electron transfer medium | 94 |
| Wheat straw | 500 | Ball milling | 0.4% | Tetracycline | 2.17 mg kg−1 | 96% removal of tetracycline was found after the application of ball-milled biochar owing to the degradation and adsorption mechanisms | 154 |
| Maize straw | 650 | KOH | 1, 3, and 5% | Perfluorooctanoic acid | 10 μg g−1 | Application of KOH treated-biochar decreased the uptake (50%) and bioavailability (90%) of perfluorooctanoic acid in the polluted sediments | 63 |
| Corn straw | 600 | Fe/Mg-LDH | 0.5% | Sulfamethoxazole | 8 mg kg−1 | Pot experiments exhibited that treated biochar could prompt urea-hydrogen peroxide to degrade sulfamethoxazole by 68% | 84 |
| Rice husk | 500 | Bacillus siamensis | 3% | Dibutyl phthalate | 100 μg g−1 | Bacterial-inoculated biochar enhanced the biodegradation of Dibutyl phthalate in soil and reduced its uptake via leafy vegetables | 155 |
| Walnut shell | 700 | FeCl3 and Illite | 0.2 and 4% | Metolachlor | 10 to 120 mg L−1 | Application of FeCl3 and Illite co-loaded biochar boosted the adsorption capability of soil (129 mg g−1) which was greater than control soil (72 mg g−1 | 156 |
| Waste timber | 900 | CO2/steam activation | 0.1 to 5% | Polyfluoroalkyl substances | 1200 to 3800 μg kg−1 | Activated biochars at a 5% rate strongly decreased leaching amounts of poly-fluoroalkyl by 98–100% | 157 |
| Maize straw | 600 | Fe(NO3)3 and KMnO4 | 0.5, 1, and 2% | Dibutyl phthalate | 40 mg kg−1 | The residual dibutyl phthalate in grains reduced by 28 to74% under engineered biochar treatments as the dose increased, while that of un-modified biochar treatment reduced by 6 to 51%, relative to the control | 158 |
| Basket willow | 700 | Microwaves | 5% | PAHs | 39.9 mg kg−1 | The application of modified biochar decreased the dissolved PAH concentration in soils by (85%) relative to the unamended soils | 50 |
| Biogas residues | 700 | Potassium ferrate | 1% | Benzo[a]pyrene | 8.16 mg kg−1 | The Fe-loaded biochar coupled with ammonium persulfate resulted in the degradation amount reaching 91% after 72 h in polluted soil | 67 |
| Sewage sludge | 700 | Rhamnolipid | 2% | Petroleum | 50,048 mg kg−1 | Rhamnolipid-doped biochar exhibited superior capability for the degradation of petroleum than raw biochar (32 vs 21%) | 156 |
| Bur cucumber shoot | 700 | H2SO4 | 2% | Sulfamethazine | 10 mg L−1 | The loamy sand soil after H2SO4-treated biochar application exhibited a higher adsorption capacity for sulfamethazine, (182 mg kg−1) | 157 |
| Buffalo nutshell | 500 | Lanthanum ferrite | 0.75 g L−1 | PAHs | Total 61,586 ng g−1 | With the application of lanthanum ferrite-loaded biochar, the total PAHs elimination reached (76%) which could be attributed to the interactions between the graphitized biochar network and surface oxygen species at lanthanum ferrite defective sites | 158 |
| Olive residue | 400 | Potassium permanganate | 2.5% | Pentachlorophenol | 2 to 30 μg g−1 | The treated biochar was capable of achieving the maximum rates of remediation and great removal of extractable pentachlorophenol under both anaerobic and aerobic conditions | 159 |
| Palm branches | 300 | Chitosan | 1% | Imazapyr and imazapic herbicides | 500 mg L−1 | For the removal of imazapyr and imazapic, the chitosan-doped biochar-amended soil respectively exhibited 84% and 73% removal efficacy, greater than control soil (8% and 50%) | 160 |
| Giant reed | 500 | Cupric nitrate | 40% | Phenanthrene | 0.013 mg L−1 | Constructed wetlands with cupric nitrate-doped biochar eliminated (94%) phenanthrene | 161 |