Fe(III)-exchanged zeolites as efficient electrocatalysts for Fenton-like oxidation of dyes in aqueous phase.

Electrochemical oxidation, a powerful tool for the conversion of several of organic dye compounds using metal-exchanged zeolite modified electrodes, has shown great potential due to its capability of high efficiency degradation, a global priority for a sustainable environment. In this study, the role of the Fe(III)-exchanged-zeolite-modified electrodes using two different zeolite structures (such as FAU (Y) and MFI (ZSM-5)) on the Fenton-like oxidation of Congo Red dye (C 32 H 22 N 6 Na 2 O 6 S 2) was investigated at room temperature. To clarify the electrocatalytic trend observed by constant potential electrolysis, the surface acidity of the catalysts prepared by ion-exchange method was determined by microcalorimetric measurements of ammonia adsorption. The different acid properties deriving from the presence of different cations (NH 4 ⁺, H⁺ and Na⁺) in the case of MFI structure were found to enhance the ion-exchange capacity as well as the oxidation reaction. MFI catalysts - Fe(Na)ZSM-5, Fe(H)ZSM-5 and Fe(NH 4)ZSM-5 - exhibited excellent activity and stability at the end of the electrolysis (within 60 min), with a total dye degradation and an higher mineralization on Fe(H)ZSM-5 (64% of TOC), compared with Fe(Na)Y nano , which takes twice as long (120 min) for total degradation, with 19% of TOC removal. This work provides an effective route for the development of stable Fe(III)-zeolite-modified electrodes for electro-Fenton oxidation, with a better stabilization of Fe³⁺ ions within the framework, without the aggregation of iron and the addition of H 2 O 2 , at room temperature. [Display omitted] • Easy preparation of Fenton-like catalysts based on zeolites, MFI and FAU. • Highly effective Fe(III)-zeolite-modified electrodes to electro-Fenton oxidation. • Electrochemical method allows faster mineralization of dye without redox agents at RT. • Eco-friendly Fenton-like oxidation was achieved with MFI-zeolite catalysts. [ABSTRACT FROM AUTHOR]