Development of a Regenerable Fe-Ag/CNF Catalyst for the Oxidation of Organics-Laden Wastewater

The present study introduces an activated carbon bead-supported regenerable bimetal (Fe-Ag) catalyst for the catalytic wet air oxidation (cWAO) of organics in an industrial wastewater (chemical oxygen demand/COD ~ 120000 mg/L). The catalytic oxidation reaction is performed at 27 bar and 230 °C in a trickle bed reactor. The Fe-Ag nanoparticles-modified carbon nanofibers enhance the exposure of the bimetals to the aqueous organics during oxidation. The spent cWAO catalyst is regenerated through simple solvent-washing and H₂-reduction steps. The SEM, XRD, Raman, and XPS spectroscopic results indicate that the physicochemical properties of the fresh catalyst, including the materials specific surface area are retained in the regenerated catalyst. The regenerated catalyst shows approximately the same efficiency (~ 99% COD reduction) as that of the fresh catalyst in three consecutive oxidation-regeneration cycles. The bimetal catalyst developed in this study for the treatment of aqueous organics is cost-effective and scalable. Graphical Abstract: (Figure presented.)