Role of the pore structure of Fe/C catalysts on heterogeneous Fenton oxidation

The aim of this work is to evaluate the influence of the pore structure of Fe-supported carbon catalysts in heterogeneous Fenton oxidation. For such goal, two types of porous carbons i.e. biomass-derived carbon (BDC) and polymer-derived carbon (PDC) were employed as catalytic supports. Both solids present the same specific surface area (ca. 1300 m2/g) but a different character of porosity. The former showed a remarkable pore fraction in the range of micropores (<2 nm) whereas the latter displayed substantial pores in the range of micro- and mesopores (2-5 nm). The Fe2O3/carbon catalysts were produced by wet impregnation of iron oxide precursor followed by calcination at 300 °C. Elemental mapping of EDX analysis confirmed the evenly distribution of metal on carbon, which Fe loading was set to 0.5, 1 and 2 wt.. Remarkably, the specific surface area of the supports remained almost unchanged after the immobilization of iron oxide (below 5 drop). The performance of the catalysts was investigated in the oxidation of methylene blue (MB) under ambient conditions (MB0 = 20 mg L-1; H2O20 = 12.5 mL L-1; catalyst = 125 mg L-1; 30 °C). The experimental data were successfully described by an intraparticle gradient model with first order of reaction of methylene blue and accounting adsorption equilibrium. The mass transfer and reaction parameters showed that the porous structure of the support plays a key role on the oxidation process. Iron oxide dispersed on mesoporous support was more advantageous i.e. featuring a higher reaction rate constant (40% increase in removal capability). Regarding the stability, the mesoporous catalyst maintained its high activity upon four consecutive runs. © 2019 Elsevier Ltd.