Fenton-Type Bimetallic Catalysts for Degradation of Dyes in Aqueous Solutions

Abstract

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.

Degradation of pollutants in water by Fenton-like oxidation over LaFe-catalysts: Optimization by experimental design

“…Concerning the monometallic catalysts, higher conversions are shown for FeZSM5 (violet curves) in comparison with LaZSM5 (orange curves), with much more notable differences in the case of Tar. This is not surprising since iron is a J o u r n a l P r e -p r o o f crucial metal for Fenton reactions, as already reported in other works [15][16][17]20,35,36,49,50]. Interestingly, for both pollutants, the catalyst LaZSM5 (orange curves) shows comparable conversions with 34.7 % and 40.1 % for Tar and Caf, respectively.…”

“…After centrifugation, the solution was analyzed in order to quantify the degradation of the organic pollutants with the help of UV-vis and TOC analyses. An UV-vis spectrophotometer (UV-2501PC from Shimadzu) was used at the characteristic wavelengths max= 427 nm and 272 nm for Tar and Caf, respectively [20,26,27].…”

“…For Caf degradation, it seems that the H2O2 concentration is not important compared to other factors. temperature in order to achieve the best compromise for a better degradation [20,35,36]. Table 3 shows the optimal conditions determined by using the Box-Behnken design for obtaining the maximum pollutants' degradation by Fenton-like oxidation.…”

“…In the case of zeolites, Cu(II) or Mn(II) were ion-exchanged together with Fe(III) ions in NaY zeolite and used as bimetallic catalysts in Fenton-like oxidation for removing two dye compounds (procion yellow (PY) and tartrazine (Tar)). CuFe-NaY and MnFe-NaY displayed the best mineralization rates for PY and for Tar degradation [20].…”

“…These heterogeneous catalysts offer a great stability of the active centres, present limited leaching of metals from the catalyst, are easy recoverable from the reaction medium, and can be regenerated by a suitable activation procedure [15][16][17]. In addition, the utilization of clays or zeolites as catalysts for Fenton-like reaction is very attractive, due to the selective sorption capacities , nontoxic nature, availability, and low cost [15][16][17]19,20] of these porous materials.…”