Monitoring fate and behaviour of Nanoceria under relevant environmental conditions

Abstract

The exponential use of engineered nanoparticles (ENPs) in commercial applications and of their resultant increasing release into the aquatic systems raises concerns as their potential impacts are unknown. According to the Organisation for Economic Co-operation and Development (OECD) ceria oxide nanoparticles (nCeO2) are among priority nanomaterials in need of immediate risk assessment owing to their increasing production and application in products. Herein we present findings on the transformation of nCeO2 nanoparticles exposed to varied concentrations and type of natural organic matter (humic acid and alginate) as a function of time; as well as pH using nanoparticle tracking analysis (NTA) and Transmission Electron Microscope (TEM). The results revealed significant tendency of nCeO¬2 to undergo aggregation, agglomeration and certain degree of deagglomeration processes under different environmental conditions. Moreover, the findings suggested that both electrostatic and steric interactions influenced the stability of the nanoparticles in aqueous media. Thus, nCeO2 stability kinetics is dependent on the physicochemical properties of the exposure media, and in turn plays a significant role with respect to risk assessment of ENPs including undergoing different forms of transformations after entry in the environment.