Fenton-type bimetallic catalysts for degradation of dyes in aqueous solutions

Dye compounds are becoming a problematic class of pollutants for the environment, so it is important to develop stable catalysts for their elimination. First, several studies were performed with different Y zeolites (NaY, (NH4)Y and USY) in order to select the best support for the preparation of the bimetallic catalysts. In particular, NaY zeolite was used as the support for Fe, Cu and Mn metals to prepare mono and bimetallic Fenton-type catalysts by the ion exchange method. The catalysts were characterized by several techniques, such as chemical analysis, nitrogen physisorption, X-ray diffraction (XRD), scanning electron microscopy (SEM) and cyclic voltammetry studies. Characterization results revealed that the metals were successfully ion-exchanged within the NaY zeolite. The prepared catalysts were tested for the aqueous-phase degradation of dye compounds (Procion yellow (PY) and Tartrazine (Tar)) at atmospheric pressure and different temperatures, using H2O2 as the oxidant. All the investigated samples were found to be active in degrading the dyes through the Fenton-type process; however, the oxidation rate was found to be higher in the presence of the bimetallic catalysts. CuFe-NaY displays the best mineralization rate for PY oxidation while MnFe-NaY shows the highest activity for Tar degradation. This work may provide further insight into the design of Fenton-type bimetallic catalysts with improved catalytic properties for environmental remediation.This research work has been developed under the scope of the projects: BioTecNorte (operation NORTE-01-0145-FEDER-000004), supported by the Northern Portugal Regional Operational Programme (NORTE 2020), under the Portugal 2020 Partnership Agreement, through the European Regional Development Fund (ERDF). This work also has been funded by national funds (Fundação para Ciência e Tecnologia, FCT), through the projects: PTDC/AAGTEC/5269/2014, Centre of Chemistry (UID/QUI/00686/2013 and UID/QUI/0686/2016) and Associate Laboratory LSRE-LCM-UIDB/50020/2020. OSGPS acknowledges FCT funding under the Scientific Employment Stimulus—Institutional Call CEECINST/00049/2018.