Environmental Impacts on the Photocatalytic Activities of Anatase and Rutile

Titanium dioxide (TiO2) nanoparticles (NPs) are widely used in various industries and are increasingly found in environmental systems, especially in soil. However, the environmental behavior of TiO2 NPs is still poorly understood. Hence, this study aims to fill this gap by investigating the short- and long-term effects of soil solutions on anatase and rutile NPs. The experiments were carried out using two soil types, which have very different chemical properties, in order to obtain a more nuanced picture of how these factors affect the stability, surface chemistry, and photocatalytic activity of TiO2 NPs. The results indicate that acidic soil solutions with lower ionic strength tend to enhance the stability of TiO2 NPs by preventing aggregation, while alkaline solutions with higher ionic strength promote aggregation and reduce photocatalytic activity by blocking active sites. Additionally, the adsorption of organic matter and other soil components on the nanoparticle surface further complicates their behavior, potentially reducing their photocatalytic efficiency. The interaction time plays a crucial role in determining the long-term fate of TiO2 NPs in soil environments. Extended exposure to soil solutions leads to changes in crystallite size, surface charge, and the adsorption of functional groups, which, in turn, affect the NPs’ photocatalytic properties.