Abstract
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.
Highlights
In recent decades, with the rapid development of industries such as chemical industry, mining industry and agricultural breeding industry, environmental pollution problems, including water pollution, have become increasingly serious
In this study, grinding depolymerization, dispersion and particle composition were integrated; the CaCO3 –TiO2 composite photocatalyst was prepared by directly dry grinding CaCO3 and nano-TiO2 powder in a grinding machine, which has the advantages of requiring a simple process and low cost
The photocatalytic performance of CaCO3 –TiO2 composite photocatalyst was tested with methyl orange as the target degradation product
Summary
With the rapid development of industries such as chemical industry, mining industry and agricultural breeding industry, environmental pollution problems, including water pollution, have become increasingly serious. Many studies have shown that loading nano-TiO2 on the surface of the carrier with a large particle size to prepare a composite photocatalyst can effectively solve the above problems [11,12,13]. Sun et al prepared CaCO3 –TiO2 composite pigment by liquid phase mechanical chemistry with CaCO3 as the carrier This process requires a large amount of water, and subsequent processes such as filtration and drying are required, which are complicated and consume more energy. In this study, grinding depolymerization, dispersion and particle composition were integrated; the CaCO3 –TiO2 composite photocatalyst was prepared by directly dry grinding CaCO3 and nano-TiO2 powder in a grinding machine, which has the advantages of requiring a simple process and low cost. The combination mechanism between CaCO3 and TiO2 and the improvement mechanism for the photocatalytic performance of nano-TiO2 were discussed
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