Influence of the morphology and the surface chemistry of carbons on their catalytic performances in the catalytic wet peroxide oxidation of organic contaminants

The catalytic behavior of five different carbon materials (mesoporous graphite-like carbon Sibunit, catalytic filamentous carbon (CFC), nano-diamonds (ND) and onion-like carbon (OLC)) in the catalytic wet peroxide oxidation of model organic compounds with different sorption capacities and stability towards oxidation (phenol, ethanol and formic acid) has been examined, in the absence and in the presence of Fe3+ ions. All the bare carbons showed extremely low catalytic activity in the oxidation of phenol, ethanol and formic acid in the absence of iron. The homogeneous Fe-catalyzed oxidation of all substrates was much faster. Furthermore, in the Fe-promoted catalytic oxidation over carbons, the presence of ND inhibited the oxidation of the model substrates compared to the homogeneous Fe3+-catalyzed oxidation. On the contrary, the other carbon samples (OLC, CFC, Sibunit) accelerated the oxidation of ethanol and formic acid under the same reaction conditions. More complex effects were observed for OLC, СFС and Sibunit in the oxidation of phenol. A tentative mechanism is discussed.