Fe(III)-Exchanged Zeolite As Efficient Electrocatalysts for Electrodegradation of Congo Red Dye

Abstract

The role of the nanostructured iron catalysts hosted by different type of zeolite structures (NaY and ZSM5) on the electrochemical degradation of Congo Red dye (C32H22N6Na2O6S2) was investigated. Here, the nano-iron zeolite catalysts with high surface areas (up to 853 m2 g-1) were prepared by ion-exchange method1 serving tunable particle size and acidity that is highly sensitive to the local reaction environment at the electrode surface. The structural and morphological analysis was carried out using scanning electron microscopy (SEM), X-ray diffraction and N2-sorption techniques. In order to clarify the electrocatalytic trend observed by constant potential electrolysis, we further considered the acidity properties of the zeolites determined by microcalorimetric measurements. Moreover, it was noted that the presence of NH4 +, H+ and Na+ ions in the case of ZSM5 zeolite allows the rearrangement of the iron-zeolite architecture, resulting in a more favorable stabilization of the degradation process as a function of the production rate. Compared with the FeNaY catalysts, the FeZSM5 catalysts (Fe(Na)ZSM5, Fe(H)ZSM5 and Fe(NH4)ZSM5) exhibited excellent activity and stability, with a maximum dye degradation around 64% on the Fe(H)ZSM5 catalyst. This work, revealing the synergetic interactions between the acid sites of the zeolite and the catalytic active sites, provides a new route for the development of electrochemical sensing low-metal content zeolite structures.Acknowledgements:This work was conducted in the framework of the BioTecNorte projects: NORTE-01-0145-FEDER-000004, PTDC/AAGTEC/5269/2014, UID/QUI/00686/2013, and UID/QUI/0686/2016. Z. B. is grateful for ERASMUS research grant.Reference:1. M. Ferreira, F. Pinto, O. S. G. P. Soares, M. F. R. Pereira, J. J. M. Órfão, J. L. Figueiredo, I. C. Neves, A. M. Fonseca, P. Parpot, Chemical Engineering Journal, 228 (2013) 374.