Abstract:

To prepare catalysts with high activity in the Fenton reaction toward the decomposition of pollutants in water, SiO₂ coated polyacrylate and manganese dioxide composite colloids(PAA-Mn@SiO₂) were carbonized under N₂ atmosphere. The synthesis process is very facile and effective. The as-prepared manganese oxides-carbon@SiO₂ core shell type catalyst (MnO_X-C@SiO₂) was characterized by X-ray diffraction(XRD), X-ray photoelectron spectroscopy(XPS), scanning electron microscope(SEM), transmission electron microscope(TEM) and the specific surface area analysis. The results indicate that low-valenced manganese oxides(Mn₃O₄ and MnO) are formed in the MnO_X-C@SiO₂ due to the reductive atmosphere formed by the pyrolysis of PAA, which is beneficial for the enhancement of the catalytic performance in the Fenton reaction. In addition, the SiO₂ shell not only effectively prevents the inside manganese oxide nanoparticles from getting larger but also stops the product from aggregating during carbonation. The carbon component in the core can further stabilize the manganese oxide nanoparticles and promote the enrichment of organic pollutants. The specific surface area of the MnO_X-C@SiO₂ is 317.3 m²/g, which is well dispersed in water. For the catalytic degradation of methylene blue(MB) solution via the Fenton process, the degradation rate of MB can reach ~96.8% only after 40 min.

Key words: manganese oxide, carbon, silica, core-shell structure, catalysis