Synthesis and stabilities of Fe, Ni and Zn oxide incorporated colloidal TiO2

Abstract

Owing to the unique physical and chemical characteristics of nanoparticles (NPs), their use in the manufacturing of commercial products is on the rise. The future will see an increasing quantity of NPs being discharged into our surroundings. This is precisely why it is important to understand their stability under changing conditions. This research examined the role of added Fe (III), Ni (II) and Zn (II) on the formation and stabilities of aqueous colloids of TiO2 particles. To the best of our knowledge, this is the first attempt to investigate the stability of lab synthesized composite NPs. The study confirmed that both the stability and environmental fate of metal oxide and mixed metal oxide NPs depends on the composition of aqueous environment. This can add more to the general understanding of NPs while paving way for exploring the stability and environmental fate of various mixed metal oxide/composites NPs as previous studies explored only commercially prepared plain NPs. TiO2 and TiO2-Fe2O3, TiO2-NiO, and TiO2-ZnO were synthesized following reported methods. Different characterization techniques including transmission electron microscope (TEM), x-rays diffraction (XRD), energy dispersive X-ray (EDX) analysis, and dynamic light scattering (DLS) were used to confirm the surface morphology, phase, elemental composition, and hydrodynamic (Dh) size of synthesized TiO2 particles. As-synthesized TiO2 and its various forms (TiO2-Fe2O3, TiO2-NiO, and TiO2-ZnO) showed rapid aggregation behavior in solutions, which is a sign of less or no threat to human health and the environment. Among the synthesized composites, TiO2-Fe2O3 showed the highest stability across all the methods utilized in this research. For all the approaches employed in dispersing aggregates of TiO2 NPs and their composites in solution, homogenization method displayed the highest efficiency. Moreover, the addition of an electrolyte i.e., KCl into the particle suspensions has affected the ionic strength of these suspensions resulting in an increased aggregation due to the shifting of ions-particles equilibrium. Thus, the formation of composites on TiO2 can govern both the stability and environmental fate of TiO2 particles under various aqueous environments.