Photochemical reactivity of aqueous fullerene clusters: C60 versus C70

Over the past few years, there has been a strong interest in exploring the potential impact of fullerenes in the environment. Despite that both C-60 and C-70 have been detected in environmental matrices, the research on the impact of higher fullerenes, such as Cm, has been largely missing. This study evaluated and compared the phototransformation of aqueous C-60 and C-70 clusters (nC(60) and nC(70)) and their O-1(2) production under sunlight and lamp light irradiation (315 nm, 360 nm and 420 nm). The nC(60) and nC(70) samples formed by direct mixing with water adopted a face-centered cubic (FCC) crystal structure. The apparent quantum yields (AQYs) of fullerene phototransformed were relatively constant over the examined wavelengths, while O-1(2) production AQYs decreased with increased wavelengths. The long-term fate studies with outdoor sunlight indicated that both nC(60) and nC(70) lost considerable organic carbon contents (>80%) in water after similar to 8 months of irradiation and that the intermediate photoproducts of nC(60) and nC(70) exhibited a progressively increased level of oxygen-containing functionalities. Overall, the study indicates that nC(70) can be photochemically removed under sunlight conditions and that the photoreactivity of nC(60) based on AQYs is greater than that of nC(70). (C) 2016 Elsevier B.V. All rights reserved.