Influence of Ca species on the surface properties of TiO₂ nanoparticles and its possible transformation

Metal oxide (e.g., TiO₂) nanoparticles have been used in various environmental, food and medical products. Other chemical species, e.g., major cationic or anionic compounds, are also found in these applications. However, limited information on the interactions of nanoparticles with the other chemical species is available. Thus, this study aimed to examine interaction of TiO₂ nanoparticles with individual and combined presence of Ca compounds by the surface chemistry of TiO₂ nanoparticles using dynamic light scattering, Fourier transform infrared spectrometry and energy-dispersive X-ray spectroscopy. Moreover, surface characteristics such as crystallinity, functional group indices (hydroxyl, carbonyl and vinyl), oxygen to carbon ratio, as well as the influence of surface characteristics on the zeta potential and particle sizes were evaluated. The results indicated that the crystallinity, oxygen to carbon ratio, hydroxyl and vinyl groups of TiO₂ nanoparticles were significantly affected from the interaction with Ca compounds. As a result of surface transformation, affecting the functional groups and crystallinity, the zeta potential and particle size were significantly influenced.