A comparative study about the effects of isomorphous substitution of transition metals (Ti, Cr, Mn, Co and Ni) on the UV/Fenton catalytic activity of magnetite

Magnetite catalysts doped by five common transition metals (Ti, Cr, Mn, Co and Ni) on a similar level were prepared by a precipitation-oxidation method and characterized by chemical analysis, XRD,TG-DSC, BET surface area and XANES. The effects of substituting metal species on the photocatalytic performance of magnetite were investigated and compared through the UV/Fenton degradation of tetrabromobisphenol A (TBBPA). The substitution of above metals improved the heterogeneous UV/Fenton degradation of TBBPA, and the improvement extent increased in the following order: Co < Mn < Ti approximate to Ni < Cr. Fewer intermediate product species were detected in the systems with higher degradation efficiency. The distinct effects of these substituting metals on the UV/Fenton catalytic activity of magnetite were discussed in terms of reaction mechanism and surface property varieties. The substituting cations participated in the H2O2 decomposition through Haber-Weiss mechanism and enhanced separation and transfer efficiency of the photo-generated electrons and holes, both of which improved the generation of (OH)-O-center dot free radicals. Furthermore, with larger specific surface area and higher surface hydroxyl amount, substituted magnetite exhibited stronger catalytic activity for TBBPA degradation. (C) 2013 Elsevier B.V. All rights reserved.