Preparation Of CoFe₂O₄/Titanate As Heterogeneous Catalysts Of Peroxymonosulfate Activation For Degradation Of Organics

In recent decades, environment pollution issues have been threatening the lives and health of people. Hydroxyl radicals-based Fenton reactions were studied and applied widely, however, the low efficiency and narrow p H usage still hindered their development. The research about sulfate radicals which can be produced by reactions between transition metal ions and peroxymonosulfate became a hot spot. In this field, the preparation of heterogeneous catalysts was the key factor because hazardous metal would cause secondary pollution to the solution. In this paper, based on these results, we prepared two kinds of cobalt ferrite / layered titanate with different morphologies to reduce the leached metal ions by the anion-exchange of titanate and this will also provide a new way to the future.Cobalt ferrite / layered titanate nanotubes（ Co Fe₂O₄/TNTs） were prepared by an impregnation- calcination method, XRD、TEM、N2 absorption- desorption and other methods were used to record their crystallographic and micro-structures, VSM was also used to study their magnetic properties. During the catalytic reactions, Rh B was adopted as a model pollutant, a series of catalysts were compared for activation of peroxymonosulfate, besides, the influence of some parameters like the dosages of catalysts and oxidant, temperatures and p H were analyzed systemically. Hydroxyl and sulfate radicals were both identified as the main species produced according to the classical radicals competing tests. Compared to the Co Fe₂O₄, the composites own better performance and less cobalt ions leaching, which means as a kind of novel substrate, titanate nanotubes not only can make the active sites more dispersed but also will surpass the metal ions leaching by strong anion-exchange functions.Hydrothermal method was applied to get the Co Fe₂O₄ microspheres with mean size, and SiO₂ was used as the template, finally Co Fe₂O₄@ titanates could be formed after the coating of titania and subsequent etching process. We used the phenol as the modal pollutants, and studied the effects of various parameters to this system. TEM results revealed that the surface of core-shell structures were made up numerous titanate nanosheets, the double-shelled characteristics would endow much porosity and benefit to the transportation process of the reactions. On the other hand, ICP results showed that the leached cobalt concentration was dramatically reduced from 12.0 mg/L to 2.9 mg/L, which means that the spatial effect and chemical anion-exchange process both can realize the reduction of the metal ions leached concentration. Radical competing tests revealed sulfate radicals play a more important part than hydroxyl radicals, for recycling of the catalyst, its performance showed a little decrease but also could realize the same efficiency under 100 min.