Degradation of octane using an efficient and stable core-shell Fe3O4@C during Fenton processes: Enhanced mass transfer, adsorption and catalysis

Volatile organic compound (VOC) elimination technologies have been investigated to alleviate health damage and to reduce serious environmental risks. The degradation of hydrophobic and refractory VOCs calls for advanced oxidation processes with high degradation efficiency and low-level toxic byproduct generation. In this study, core-shell Fe3O4@C was employed as an advanced oxidation microreactor for hydrophobic and refractory VOC removal during the Fenton process, and octane was chosen as a typical target pollutant. The average octane removal efficiency increased by 41.6%, while the main byproduct concentrations decreased by 65.8% in the initial 60 min compared with Fe3O4. Density functional theory (DFT) calculations revealed the key role of Fe-O-C bond during the regeneration of Fe(II) species, and the enhanced octane adsorption process by the carbonyl sites. Calculation of mass transfer enhancement factor proved that the carbon shell was critical during mass transfer process. The advanced oxidation mechanism was investigated by detection and measurement of byproducts and hydroxyl radicals and XPS analysis. The synergism and the octane degradation pathway was proposed based on the two main types of reactions. This core-shell Fenton system suggests a promising approach for catalyst and microreactor design in advanced oxidation technologies for refractory VOCs removal.