“…The surface chemistry of activated carbons can be modified, as previously stated, through various post-synthesis treatments [ 104 , 105 ], which do not only involve the acidic-basic character of the surfaces, but also the nature of the surface heteroatoms. As mentioned, the existence of certain oxygenated groups functionalities confers acidic properties, hence why the acidic character of ACs is frequently developed through heat treatment in the gas phase with oxygen, ozone, carbon dioxide, steam, and nitrous oxide (150–700 °C) [ 74 , 90 , 92 ], or liquid phase with oxidants such as nitric acid, hypochlorite, permanganate, or hydrogen peroxide [ 106 , 107 , 108 ].…”