Photocatalytic and surface properties of titanium dioxide nanoparticles in soil solutions

Abstract

Nanotechnology has emerged as a rapidly growing scientific field with diverse applications. Titanium dioxide nanoparticles are among the most commonly used nanoparticles due to their unique properties. However, their release into the environment poses potential ecological risks to the soil, groundwater, and aquatic systems. Therefore, this study explores the behavior of anatase and rutile nanoparticles in Chernozem soil solutions, focusing on their optical, surface, and photocatalytic properties. After immersion in soil solutions, both anatase and rutile nanoparticles exhibited optical changes, while their semiconductive properties, as indicated by the band gap, remained unaltered. Rutile nanoparticles displayed a decreased isoelectric point after interaction with soil solutions, probably due to deprotonation based on infrared spectroscopy results. Photocatalytic activity assessments revealed a slowdown in the case of anatase by 14% and rutile by 27% after exposure to soil solutions. However, after a three-hour degradation process, the titanias regained their initial levels of activity. The reduction in photoactivity was attributed to adsorption onto the surface of nanoparticles of Zn²⁺, Ca²⁺, PO₄³⁻ organic molecules (such as amines, alkenes, and carboxyl groups) present in the soil solution, hindering catalytic reactions. Anatase nanoparticles exhibited superior performance compared to rutile, which can be attributed to their larger specific surface area and higher hydrophilicity, resulting in the enhanced generation of reactive species. This study provides valuable insights into the complex interactions between nanoparticles and soil solutions, shedding light on their optical properties, surface characteristics, and catalytic activity.