Table 6 Recent advances in biochar modification by minerals and their effectiveness in environmental application.
Objectives | Modify agent | Environmental application | Key results | References |
|---|---|---|---|---|
Provide a large number of hydroxyl groups | Montmorillonite | Adsorption of atenolol (86.86 mg g−1) and Pb (II) (139.78 mg g−1) | Amino O and amino N produced hydrogen bonds on the modified biochar surface | |
Enhance the surface area | Montmorillonite | Immobilization of Zinc, Copper, and lead in soil | FTIR and sorption experiments results showed that chemisorption was the prevalent immobilization process | |
Improve the surface area | Montmorillonite | Tetracycline sorption (77.96 mg g−1) | The leading sorption mechanism was Physisorption | |
Precipitate Pb | Hydroxyapatite | Pb immobilization in the soil | The residual fraction of lead enhanced by 66% after the addition of modified biochar | |
Stimulate surface complexation and enhance surface area | Goethite | Immobilization of phosphorous, cadmium, roxarsone, and arsenic in the soil | Co-precipitation, surface complexation, redox reaction, and ion exchange attributed to the immobilization process | |
Enhancement of pore structure | Diatomite | Methylene blue sorption capacity (153 mg g−1) | The modified biochar has numerous pore channels in the mesoporous area, supporting the dye sorption | |
Produce active oxygen species via S and Fe addition | Hematite | Norfloxacin sorption (about 1.90 mg g−1) | Hematite loading successfully produced · SO−4 and –OH, stimulating the norfloxacin degradation | |
Increase ion exchange for anions | Mg–Al | Phosphate sorption (80.43 mg g−1) | the adsorption capacity of phosphate enhanced with the enhancement of the Al3+/Mg2+ ratio due to weakened inter-layer charge density and widened inter-layer space | |
Increase ion exchange for anions | Zn-Al | Phosphorus sorption (152 mg g−1) | Inter-layer complexation and anion exchange were major sorption mechanisms | |
Increase ion-exchange | Mg–Al | Methylene blue sorption (406 mg g−1) | Within 20 min the adsorption mechanism could reach an equilibrium | |
Promote anions for co-precipitation | Mg-Fe | Sorption of lead (476 mg g−1) | Co-precipitation among hydroxyl groups of surface and Pb (II) was the leading sorption mechanism | |
increase ion exchange | Attapulgite | Immobilization of cadmium and arsenic in sediment | Compared with pristine biochar, modified biochar had greater pore volume, surface area, higher CEC, and a large amount of O-enrich groups | |
Increase ion exchange | Attapulgite | Sorption of oxytetracycline (33 mg g−1) | Complexation, ion exchange, and hydrogen bonding contributed to great sorption capacity |
