Impact of natural organic matter on the physicochemical properties of aqueous C60 nanoparticles

Existing toxicity data indicate that industrial-scale production of C-60 fullerene poses a potential threat to the environment. Evaluating the environmental impact of C-60 requires careful characterization of its physicochemical properties in the natural aqueous environment. Our study aims to determine the effects of aquatic natural organic matter (NOM) on the physicochemical properties of aqueous C-60 nanoparticles, nC(60). Stable nC(60) suspensions were formed using three different solvent exchange protocols. They were thoroughly characterized for particle size, morphology, and electrophoretic mobility in the absence or presence of two model NOM components, Suwannee River humic acid and fulvic acid. NOM caused disaggregation of nC(60) crystals and aggregates under typical solution conditions of natural water, leading to significant changes in particle size and morphology. Such effect increased with increasing NOM concentration. The changes in nC(60) size and morphology strongly depended on the nC(60) formation pathway. Results from this study indicate that NOM may play a critical role in the transport and toxicity of C-60 in the natural aqueous environment.