Nano-TiO2-Enhanced Surface Functionalization of Recycled Concrete Aggregates for Improved Degradation Efficiency of Low-Concentration Sulfur Dioxide

This study investigates the enhancement of recycled concrete aggregate (RCA) surfaces with nano-TiO2 for an improved degradation of low-concentration sulfur dioxide (SO2). Nano-TiO2 particles, known for their photocatalytic properties, were uniformly deposited on RCA surfaces. Upon exposure to SO2 under light irradiation, the functionalized RCA exhibited significantly improved degradation efficiency. This was attributed to the photo-induced oxidation of SO2 by nano-TiO2. Enhanced degradation was further observed under UV light due to increased photoactivation. The nano-TiO2 coating also showed good durability and stability, ensuring long-term effectiveness. The experimental outcomes reveal that TiO2-treated recycled aggregates exhibit an 85% retained photocatalytic activity post five cycles of reuse. Furthermore, the investigation employs a second-order polynomial-based mathematical fitting function to generate a three-dimensional trend surface, visually illustrating the inverse relationships between sulfur dioxide degradation and environmental variables, such as initial concentration and flow rates. Finally, this study demonstrates the potential of nano-TiO2-modified RCA for mitigating the environmental impact of low-concentration SO2, contributing to the development of more sustainable construction materials and broadening RCA’s applications in environmental remediation.