Table 17.

Loading capacities of different biochar-based materials towards different organic pollutants

Raw feedstock	Temperature	Production pathway	Target contaminant	Maximum adsorption capacity (mg g−1)	Adsorption mechanism	References
Orange peel waste	150–600 °C	Microwave pyrolysis via carbon dioxide and steam activation	Congo red	136.00	Electrostatic interaction	Yek et al. (2020)
Hickory chips	600 °C	Pyrolysis followed by impregnation with iron (II, III) oxide	Methylene blue	500.5	Electrostatic interaction and π–π interaction	Li et al. (2020e)
Switchgrass	900 °C	Pyrolysis	Orange G	38.2	Electrostatic interaction, and π–π interaction	Park et al. (2019)
Frass of mealworms	800 °C	Pyrolysis	Malachite green	1738.6	Electrostatic interaction, hydrogen bonding, and π–π interaction	Yang et al. (2019b)
Corncob	400 °C	Pyrolysis followed by impregnation with triethylenetetramine, and treatment with sulphuric acid	Sunset yellow	77.1	Electrostatic interaction	Mahmoud et al. (2020)
Macroalgae (Undaria pinnatifida)	800 °C	Chemical functionalisation with potassium hydroxide followed by pyrolysis	Rhodamine B	533.8	Electrostatic interaction, hydrogen bonding, van der Waals forces, and π–π interaction	Yao et al. (2020)
			Methylene blue	841.64
			Malachite green	4066.96
Corn straw	500 °C	Nitric acid treatment, sodium hydroxide activation, followed by pyrolysis iron (III) chloride modification	Malachite green	515.8	Electrostatic attraction	Eltaweil et al. (2020)
Swine manure and fly ash	700 °C	Pretreatment of fly ash with sodium hydroxide, mixing with swine manure and pyrolysis	Methylene blue	131.6	Electrostatic interaction, and π–π interaction	Wang et al. (2020c)
Tapioca peel waste	800 °C	Mixing of pyrolysed feedstock with thiourea and pyrolysis	Rhodamine B	33.1	Electrostatic interaction, and Hydrogen bonding	Vigneshwaran et al. (2021)
			Malachite Green	30.18
Switchgrass	900 °C	Pyrolysis	Congo red	22.6	Electrostatic interaction, and π–π interaction	Park et al. (2019)
Wakame (macroalgae)	800 °C	Chemical functionalisation with potassium hydroxide followed by pyrolysis	Malachite green	4066.9	Electrostatic interaction, π–π stacking, hydrogen bonding, and van der Waals force	Yao et al. (2020)
Rice straw	500 °C	Pyrolysis followed by wet attrition	Methylene blue	90.91	Electrostatic interaction	Abd-Elhamid et al. (2020)
			Crystal violet	44.64
Corncob	400 °C	Pyrolysis followed by partial oxidation and amination	Congo red	89.3	Chemisorption	Faheem et al. (2019)
Chicken manure	500 °C	Pyrolysis	Phenols	106.2	Electrostatic interaction, π–π interaction, and hydrogen bonding	Thang et al. (2019)
			2,4-dinitrophenol	148.1
Alfalfa	700 °C	Pyrolysis followed by nitric acid treatment, acid pickling, and reheating	p-Nitrophenol	49.25	Hydrogen bonding, and π–π interaction	Chen et al. (2019)
Malt bagasse	500–900 °C	Pyrolysis followed by zinc chloride activation; pyrolysis followed by hydrochloric acid treatment	2-chlorophenol	150.0	Electrostatic interaction	Machado et al. (2020)
Alfalfa	650 °C	Pyrolysis	Bisphenol A	63.0	π–π interaction, and hydrophobic interaction	Choi and Kan (2019)
Rice husk	450 °C	Pyrolysis followed by potassium hydroxide functionalisation	Phenols	179.0	π–π interaction, and hydrogen bonding	Shen et al. (2020)
Furniture waste	700 °C	Pyrolysis followed by coating with fulvic acid	4-chlorophenol	133.0	Hydrogen bonding, and π–π interaction	Wu and Chen (2019)
Macroalgae	800 °C	Pyrolysis followed by hydrochloric acid treatment	Pyrene	0.19	Hydrophobic interaction	Qiao et al. (2018)
Corn straw	500–800 °C	Pyrolysis followed by mixing with potassium hydroxide, and then pyrolysis	Naphthalene	450.4	π–π interaction, and pore filling	Qu et al. (2021)
Rice husk	500 °C	Pyrolysis followed by iron (II) sulphate modification	Phenanthrene	97.6	π–π interaction, hydrophobic interactions, and pore filling	Guo et al. (2018a)
Macroalgae	800 °C	Zinc chloride and iron (III) chloride modification, followed by pyrolysis, and hydrochloric acid treatment	Naphthalene	90.0	π–π interaction, partitioning effect, and pore filling	Cheng et al. (2020b)
Alfalfa	650 °C	Pyrolysis	Sulphamethoxazole	90.0	π–π interaction, and hydrophobic interactions	Choi and Kan (2019)
Rice straw	550 °C	Pyrolysis followed by hydrochloric acid treatment	Benzoic acid	7.97	π–π interaction, and van der Waals attractions	Singh et al. (2020)
Microalgae	750 °C	Pyrolysis	Tetracycline	132.8	Hydrophobic interactions, and π–π interaction	Choi et al. (2020)
Grape pomace	350 °C	Pyrolysis	Cymoxanil pesticide	161.0	Hydrophilic interactions	Yoon et al. (2021)
Corn cob	600 °C	Pyrolysis followed by hydrofluoric acid treatment	2,4-dichlorophenoxyaceti acid (2,4-D) herbicide	34.4	Hydrogen bonding, pore filling, and π–π interaction	Binh and Nguyen (2020)
Lotus seedpod	500–650 °C	Pyrolysis followed by potassium hydroxide activation and pyrolysis	17β-estradiol hormone	183.6	π–π interaction, and electrostatic interaction	Liu et al. (2020b)

Different biomass-based feedstocks were studied against the targeted contaminants. Pre- or post-treatments were also investigated along with the temperatures at which the biochar was prepared. The maximum adsorption capacity in mg g⁻¹ along with the adsorption mechanism are provided