Fe-doped Zeolites As Heterogeneous Fenton Catalysts For The Treatment Of Dyes Wastewater

The heterogeneous Fenton reactions have gradually become one of the most effective strategies for the treatment of dyes sewage.Three Mobil Five（MFI）structure zeolites（Silicalite-1（S-1）,Zeolite Socony Mobil（ZSM-5）and Titanium Silicalite-1（TS-1））and their Fe-doped counterparts were synthesized via hydrothermal methods in this study.The most suitable carrier for the heterogeneous Fenton reaction was determined and the highly active and stable catalysts were prepared for basic dyes degradation.In addition,we promoted the degradation activities of catalysts by introducing the mesoporous structures.（1）The S-1,ZSM-5,TS-1,FeS-1,FeZSM-5 and FeTS-1 were prepared through hydrothermal methods.Characterizations such as x-ray diffraction spectra（XRD）,fourier transform infrared spectroscopy（FT-IR）,scanning electron microscope（SEM）,Uv-Vis diffuse reflectance spectrum（UV-Vis DRS）,N₂ adsorption/desorption instrument,x-ray fluorescence spectroscopy（XRF）,zeta potential,energy dispersive spectroscopy（EDS）and elemental mappings analysis were used to investigate the morphologies and physic-chemical properties of the prepared materials.The catalytic activities of all samples were evaluated by conducting the dyes degradation experiments.The results indicated that FeZSM-5 showed the highest catalytic performance among FeZSM-5,FeS-1 and FeTS-1,and thus ZSM-5 as a carrier could be more suitable for heterogeneous Fenton reactions than S-1 and TS-1.（2）The framework Fe-doped ZSM-5 zeolites（f-Fe-ZSM-5）with different Fecontents were fabricated using hydrothermal methods.The structural properties and morphologies of synthesized materials were comprehensively characterized by XRD,EDS,SEM,N₂ adsorption/desorption instrument,FT-IR,XRF and UV-Vis DRS.The reaction parameters such as Fecontent of the catalyst,H₂O₂ concentration,reaction temperature and dyes type were extensively studied.The kinetics of degradation reactions and the stability of catalysts were evaluated.In addition,the main active species were confirmed using the quench experiments,and finally a possible reaction mechanism was proposed.The results demonstrated that the degradation efficiency of f-Fe-ZSM-5 for basic dyes was higher than that for acid dyes.The f-Fe（0.10）-ZSM-5displayed excellent degradation activities even after seven consecutive runs,which demonstrated the good stability of this catalytic systems.（3）The hierarchical FeZSM-5（H-FeZSM-5）was prepared via soft-template methods to introduce the mesopores into FeZSM-5.The XRD,SEM,TEM,EDS,FT-IR,UV-Vis DRS,N₂ adsorption/desorption instrument and XRF were used to study the morphologies and physic-chemical properties of synthesized materials.Afterward,the catalytic performance of H-FeZSM-5 was compared with that of FeZSM-5.It was shown that the catalytic activity of H-FeZSM-5 was 2.3 times that of FeZSM-5.The existence of mesoporous structure improved the degradation performance of the catalysts.