Methods for improving the photocatalytic performance of cement-based materials

Abstract

The surface of cement-based materials is prone to contamination by organic substances. In this study, hollow glass microspheres (HGM) loaded with N-TiO₂ were innovatively incorporated into the cement-based materials to enhance the degradation rate of organic pollutants. Initially, hollow glass microspheres loaded with N-TiO₂ (HGM@N-TiO₂) were prepared and their microstructure and photocatalytic performance were tested. Subsequently, the Monte Carlo model was utilized to simulate the transmission depth of visible light within cement-based materials. The distribution of the loaded catalyst was adjusted by controlling the slurry viscosity to match the light transmission depth. The results indicate that N-TiO₂ prepared by the sol-gel method was uniformly loaded on the surface of HGM. When the mass fraction of the catalyst in the cement slurry was 5 % and the slurry viscosity did not exceed 0.2 Pa·s, the volume fraction of the loaded catalyst within the 0 mm ∼ 1 mm depth range was over 25 %. The degradation rate of the organic compound Rhodamine B increased from 48 % with direct addition of N-TiO₂ to approximately 78 %. When the catalyst content exceeded 5 %, the volume fraction of the catalyst on the surface of the cement-based material increased, enhancing the photocatalytic effect. However, this also led to an increase in slurry viscosity, carbonation depth, and the number of harmful pores, resulting in a decrease in mechanical properties and the durability of photocatalytic activity. In order to improve the durability, the hydrophobic modifier sodium laurate was used to reduce the carbonation depth from 2.70 mm to 0.78 mm, and the long-term photocatalytic performance was significantly improved. This study effectively addresses the common encapsulation and shielding issues associated with conventional photocatalysts, thereby increasing light transmission depth within the cement-based matrix and enhancing photocatalytic efficiency.