Nitrogen-containing functional groups promoted CO2 capture

https://doi.org/10.1016/j.ccst.2022.100059

“Experts have proposed various nitrogen-containing functional groups on the surface by reacting the biochar with nitrogen-containing reagents or activating the biochar with nitrogen-containing prerequisites. Common nitrogen-containing functional groups (amide, imine, pyridine, pyrrole, and lactam groups) promote the growth of alkalinity on the surface of biochar (Shafeeyan, 2010; Shen and Fan, 2013; Guo et al., 2018) (Table 2). Nitrogen functional groups can also contribute to enhance interactions between carbon surfaces and acid molecules, such as dipole-dipole, H-bonding, and covalent bonding and so on (Shen et al., 2010). Xu et al. obtained nitrogen-doped biochar using ammonium hydroxide ball milling, and the nitrogen functional group species doped onto the surface of the biochar were mainly amine (-NH₂) and nitrile (CN). The nitrogen-doped biochar showed a 31.6%−55.2% higher adsorption capacity of CO₂ than pristine biochar, due to the strong pole-pole interaction between the large quadrupole moment of the carbon dioxide molecule and the polar sites associated with the nitrogen functional (Xu et al., 2019).”