Understanding and predicting the environmental dispersion of iron oxide nanoparticles: a comprehensive study on synthesis, characterisation, and modelling†

Abstract

Iron oxide nanoparticles (IONPs) are among the most versatile and applied nanoparticles due to their unique properties. However, the distribution of these nanoparticles (NPs) in the environmental system presents a critical problem for understanding the generation of reactive oxygen species (ROS) and their unpredictable effect on micro and macro fauna/flora due to their chemical form. This study describes strategies to evaluate the dispersion of IONPs in environmental media under controlled conditions of pH (5–9), hardness (0–400 mg CaCO₃ per L), temperature (10–30 °C), and exposure time (0–48 h) in aquatic systems. For this purpose, iron-based nanoparticles (hematite, goethite, and magnetite) were synthesised and characterised using chemical and morphological analytical techniques. Subsequently, the effect of environmental parameters on the dispersion of NPs was investigated by developing a model using a central composite rotatable design (CCRD) with total Fe as the dependent variable. The three IONPs were synthesised with a size of less than 100 nm. It was observed that the nano-hematites and magnetites had spherical morphology, while goethite appeared as nanorods. The resulting models, integrating linear, quadratic, and combined effects, exhibited high predictive capacities of 76.4%, 93.6%, and an impressive 99.9% for nano-hematite, goethite, and magnetite, respectively. This research contributes to better understanding of nanoparticle behaviours in natural settings, providing essential insights to assess and potentially mitigate the adverse consequences of IONPs contamination in aquatic environments.