indicating physical adsorption, a weak bonding between adsorbate
and adsorbent, is involved in the removal of CO2 [49]. The low O:C
molar ratio (0.004, Table 2) suggests the minimal polarity and
highly hydrophobicity for the biochar [44]. The absence of the
O-containing functional groups on the biochar surface prevents
the formation of water clusters via H-bonding [50]. This would
facilitate the hydrophobic sites on biochar surface to attract CO2
as a non-polar compound.
Additionally, the biogas samples taken from the biocharamended
digester contained H2S concentration below method
detection limit (