Degradation Of Orange Ⅱ Wastewater By Modified Iron And Cobalt Oxides Materials Under Heterogeneous Photocatalytic Systems

CoFe₂O₄ hollow spheres and Fe-Co-SBA,the cobalt iron oxidesmodified materials,were prepared and characterized,and their photocatalytic activity was studied.Different photocatalytic degradation systems were constructed,and the degradation performance of OrangeⅡby these systems was explored.The main active species were detected to reveal the degradation mechanism.Considering the needs of practical applications,the reusability of photocatalysts was evaluated.（1）CoFe₂O₄ hollow spheres enhanced persulfate activation under visible light to degrade OrangeⅡCobalt ferrite photocatalytic material with hollow sphere structure was prepared by solvothermal method and characterized in detail.CoFe₂O₄ Hollow Spheres（CF-HS）showed high photocatalytic activity and excellent reusability.Visible light（Vis）can excite CF-HS and transfer electrons from the valence band to the conduction band for activating persulfate（PS）.The degradation efficiency of OrangeⅡby CF-HS/PS/Vis system reached 98.0% within 75 minutes.The degradation rate of OrangeⅡby CF-HS/PS/Vis system at pH=3-11 was more than 98.5%.Free radical quenching experiments and electronic spin resonance（ESR）spectra confirmed that sulfate radicals,hydroxyl radicals,superoxide radicals and photogenerated holes were the main active species in the degradation reaction.In addition,CF-HS showed excellent stability as 99.6% of OrangeⅡwas degraded after eight cycles.（2）Visible light enhanced Fe-Co-SBA activation BS/PS/H₂O₂ to treat OrangeⅡwastewaterFe-Co-SBA,the bimetallic supported photocatalytic material,was prepared by in situ spontaneous combustion,and characterized.Three different visible light（Vis）assisted heterogeneous photocatalytic systems （BS（bisulfite）/Fe-Co-SBA/Vis,PS（persulfacte）/Fe-Co-SBA/Vis and H₂O₂ （hydrogen peroxide）/Fe-Co-SBA/Vis） for degrading OrangeⅡwere investigated.The role of some significant parameters on the degradation of OrangeⅡin the three systems were studied separately and compared.The concentration of BS,PS or H₂O₂ led to a significant effect on the degradation of OrangeⅡ.In addition,BS/Fe-Co-SBA/Vis system and PS/Fe-Co-SBA/Vis system were found to be fit for a wider pH range of 3 to 9.However,we found that the initial pH of solution during the reaction had a great influence on the degradation of Orange II in the H₂O₂/Fe-Co-SBA/Vis system.The main free radicals involved in the degradation of Orange II in the BS/Fe-Co-SBA/Vis system were·OH and SO₄^-·.·OH,SO₄^-·and O₂^-·are the main free radicals in the PS/Fe-Co-SBA/Vis system,while there were mainly·OH radicals in the H₂O₂/Fe-Co-SBA/Vis system as determined by electron spin-resonance spectroscopy.Photocatalytic dye degradation mechanisms were proposed for the systems based on the generation of different radicals in each system.