Fe-Co-SBA assisted by visible light can effectively activate NaHSO3 or H2O2 for enhanced degradation of Orange II: Activation of NaHSO3 versus H2O2

Two different visible light (Vis) assisted heterogeneous photocatalytic systems (BS (bisulfite)/Fe-Co-SBA (Fe-Co-Santa Barbara amorphous material)/Vis and H2O2 (hydrogen peroxide)/Fe-Co-SBA/Vis) for degrading Orange II were investigated. The role of some significant parameters on the degradation of Orange II in the two systems were studied separately and compared. The concentration of either BS or H2O2 led to a significant effect on the degradation of Orange II. In addition, BS/Fe-Co-SBA/Vis system was found to be suitable for a wider pH range of 3-9. 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 center dot OH and SO4 center dot- while they were mainly center dot OH radicals in the H2O2/Fe-Co-SBA/Vis system as determined by electron spin-resonance (ESR) spectroscopy. Photocatalytic dye degradation mechanisms were proposed for both the systems based on the generation of different radicals in each system.