A parametric study on the decolorization and mineralization of C.I. Reactive Red 141 in water by heterogeneous Fenton-like oxidation over FeZSM-5 zeolite.

Ceyda Yaman,Gönül Gündüz

doi:10.1186/s40201-015-0162-6

Abstract

In this study, the heterogeneous Fenton-like degradation of Reactive Red 141 (RR141) in water was investigated over iron containing ZSM-5 zeolite (Si/Al = 42) prepared by ion-exchange (FeZSM-5 (42)). The catalyst was characterized by XRD, SEM, FTIR, TPR, and ICP-AES measurements. The effects of the initial concentrations of the dye and H2O2, the initial pH of the solution, catalyst loading, and the reaction temperature were investigated on heterogeneous Fenton-like degradation of RR141. The reduction of the solution initial pH from ca. 7.0 to ca. 3.5 had a positive effect on color removal. A complete color removal was achieved with all the H2O2 concentrations in the range of 0.007 - 0.067 M over the FeZSM-5 (42) catalyst after 2 h of reaction. The COD reduction increased from 52% to 81% with an increase in the amount of the catalyst. The COD reduction was affected positively with the increase in temperature from 298 K through 313 K to 323 K and then to 333 K. The initial decolorization rate was described by the equation: −rA0 = 9.4*104 e-38.8/RT CRR141,0 CH2O2,00.184 with an H2O2 concentration range of 0.007 M – 0.033 M (where R is in kJ/mol).

Highlights

Sulfonated and unsulfonated azo dyes have a negative aesthetic effect on the wastewater that is highly colored even at a low concentration of dye
Catalyst characterization The prepared catalyst was characterized by nitrogen adsorption, X-ray diffraction patterns (XRD), scanning electron microscope (SEM), Fourier transform-infrared (FTIR) spectrometer, inductively coupled plasma atomic emission spectrometer (ICP-AES), and by temperature programmed reduction (TPR) measurements
The heterogeneous Fenton-like degradation of Reactive Red 141 (RR141) in water was investigated over iron containing ZSM-5 zeolite (Si/Al = 42) prepared by ionexchange

Summary

Introduction

Sulfonated and unsulfonated azo dyes have a negative aesthetic effect on the wastewater that is highly colored even at a low concentration of dye. It is difficult to remove azo dyes in wastewater produced by textile industries using biological, physical and chemical treatment methods because of the chemical stability of these dyes, the high cost of the processes, and disposal problems. It is necessary to find an effective method for the wastewater treatment of reactive azo dyes. Heterogeneous Fenton-type catalysts have been developed by incorporating transitional metal cations such as iron ions or iron oxides into porous supports such as zeolites and pillared clays [17,18,19,20,21]. In the presence of H2O2, hydroxyl radicals (OH.) are produced by interaction of H2O2 with the iron (II) species present on the porous support. Iron (III) can react through Equations 2–4 with hydrogen

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