Intensification of catalytic wet peroxide oxidation with microwave radiation: Activity and stability of carbon materials.

Graphical abstract Highlights • Carbon materials are active in MW-CWPO, combining redox properties and hot spots. • Surface chemistry has a key role in the activity, especially for graphites. • The structure of the materials affects their stability. • AC crumbles down by hot spot formation inside micropores, causing a pop-corn effect. • Graphitic layered structure allows heat dissipation, enhancing catalyst stability. Abstract Several commercial carbon materials have been tested as catalysts in the Microwave-assisted Catalytic Wet Peroxide Oxidation process (MW-CWPO). Two graphites (G-F and G-S), two activated carbons (AC-M and AC-C), two carbon blacks (CB-V and CB-A) and silicon carbide (SiC) were selected due to their MW-absorbing properties. Phenol (100 mg L−1) was used as target pollutant, operating in batch at pH 0 3, 120 °C, 500 mg L−1 catalyst load and the theoretical stoichiometric amount of H 2 O 2 (500 mg L−1). All carbon materials showed to be active in terms of H 2 O 2 decomposition and phenol oxidation. Nonetheless, G-S and AC-M stood out as the most active materials in terms of TOC removal, with values of 94 and 93% TOC elimination, respectively. On the other hand, both carbon blacks and G-F yielded a significantly lower TOC degradation. Surface chemistry seems to rule the activity of graphites, in particular the pH slurry (4.5 for G-S and 8.4 for G-F). The most active catalysts, G-S and AC-M were used in 5 consecutive cycles in order to study their stability. While G-S remained active, AC-M. [ABSTRACT FROM AUTHOR]