Oxygen-containing functional groups of biochar for promoted CO2 capture

Pyrones, chromenes and ketones of the oxygen-containing functional groups are basic groups that contribute to the alkalinity of the surface. However, most oxygen-containing functional groups are acidic, including carboxylic acids, phenols, lactones and lactone groups (Montes-Morán et al., 2004Chiang and Juang, 2017), which are not conducive to the adsorption of acidic CO2 molecules from an acid-base reaction point of view. However, it is also believed that the introduction of oxygen atoms into the carbon surface to form acidic oxygen-containing functional groups facilitates hydrogen bonding interactions between the carbon surface and CO2 molecules, particularly carboxyl and hydroxyl groups. Carboxyl and hydroxyl groups increase the polarity of the adsorbent and facilitate the adsorption of CO2 with the quadrupole moment (Xing et al., 2014Kudin et al., 2008Song et al., 2020). Liu et al. (Liu and Wilcox, 2012) concluded that the oxygen-containing functional groups increased CO2 adsorbed in the microporous structure because the higher electron density around the oxygen-containing functional groups attracts more CO2.”

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