Degradability of aged aquatic suspensions of C60 nanoparticles

In this study, aged aqueous suspensions of C60 (nC60) were investigated in the respirometric OECD test for ready biodegradability. Two suspensions of nC60 were prepared by stirring and aged under indirect exposure to sunlight for 36 months. ATR-FTIR analyses confirmed the presence of C60-structures in the suspensions. Samples of the nC60 suspensions (20 mg/l) were inoculated with activated sludge (30 mgTSS/L) and incubated in a mineral medium under aerobic conditions. Since no mineralisation of nC60 was observed after 28 days of incubation, 5 mg/l sodium acetate was added to the media. After additional 20 days, no mineralisation of nC60 was observed. However, within a few days sodium acetate was completely mineralised, showing that the biomass was not inhibited by the presence of nC60. Based on results from this simple approach, aged nC60 can be classified as not ready biodegradable according to the standard OECD test procedure. - Highlights: → Aqueous nC60 was tested for ready biodegradability in standard OECD test. → nC60 suspensions were prepared by stirring for 36 months in indirect sunlight. → No mineralisation of nC60 was seen after 28 days incubation with activated sludge. → The biomass was not inhibited by the presence of 20 mg/L nC60. → nC60 is classified as not ready biodegradable. - Aged suspensions of nC60 were found not to be ready biodegradable according to the OECD test procedure. The biomass was not inhibited by the presence of nC60.