Synthesis of Ce-doped Mn3Gd7-xCex(SiO4)6O1.5 for the enhanced catalytic ozonation of tetracycline.

A novel cerium doped compounds Mn3Gd7-xCex(SiO4)6O1.5 with an apatite structure was found and used to achieve high-efficiency degradation of tetracycline in aqueous solution. The catalysts were characterized by XRD, XPS, EDS and other techniques. The characteristic results indicated that the catalytic activity of the compound was improved due to the introduction of Ce in the structure, because Ce3+ which was stably present in the apatite structure can serve as an active site for the reaction, and in addition, there was a high presence between Ce4+ and Ce3+ on the surface of the catalyst. The redox potential and high oxygen storage capacity were also beneficial for the catalytic reaction. The results of free radical capture indicated that both superoxide radicals and hydroxyl radicals participated in the catalytic oxidation process and played an important role in the reaction. The decomposition of tetracycline followed the pseudo second-order reaction kinetics. In addition, the catalyst exhibited long-term stability and low metal leaching during the reaction, which indicated that the novel cerium-doped apatite structure material could be a promising wastewater treatment material.