Preparation and Properties of CaCO₃-Supported Nano-TiO₂ Composite with Improved Photocatalytic Performance

In order to improve the photocatalytic degradation efficiency of nano-TiO₂, reduce its usage and realize recycling and reuse, CaCO₃-TiO₂ composite photocatalyst was prepared with calcium carbonate (CaCO₃) and TiO₂ in a grinding machine through the integration of grinding depolymerization, dispersion and particle composition. The photocatalytic degradation performance, recycling performance, structure and morphology of CaCO₃-TiO₂ were studied. The interaction mechanism between CaCO₃ and TiO₂ and the improvement mechanism for the photocatalytic performance of TiO₂ were also discussed. The results show that under the UV light irradiation for 20 and 40 min, the degradation efficiency of methyl orange by the composite photocatalyst with 40% TiO₂ (mass fraction) was 90% and 100%, respectively. This was similar to that of pure TiO₂, and the performance of the composite photocatalyst was almost unchanged after five cycles. CaCO₃-TiO₂ is formed by the uniform loading of nano-TiO₂ particles on the CaCO₃ surface, and the nano-TiO₂ particles are well dispersed. Due to the facts that the dispersion of nano-TiO₂ is improved in the presence of CaCO₃ and the charge transport capability is improved through the interfacial chemical bonds between CaCO₃ and TiO₂, the formation of this complex is an intrinsic mechanism to improve the photocatalytic efficiency of nano-TiO₂ and reduce its usage in application processes.