科研之友
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摘要
Particle size distribution of nanoparticles is critical for transport, fate, and their biological toxicity in the environment. This work employed asymmetrical flow field flow fractionation coupled with multiangle light scattering (AF4-MALS) to evaluate the effects of solution properties such as pH, ionic strength (IS), and natural organic matter (NOM) on the size distribution of nanosized C-60 during long-term mixing of C-60 powder in water. Large nC(60) clusters (a few micrometers in size) were initially formed and gradually disaggregated into small particles from 20 to 500 nm. Increasing pH from 5.65 to 9.04 made the proportion of small sized nC(60) of 30-100 nm (90.8% in particle number) disappear, whereas the percentage of 130-140 nm-sized particles gradually increased. Compared with the size distribution of nC60 formed in the pure water (130-150 nm in radius), a low ionic strength (IS) of 0.001 mol.L-1 promoted nC(60) disaggregation and simultaneously reduced the particle size of nC(60) (80-110 nm in radius). Increasing the IS to 0.01 mol.L-1 led to the aggregation of nC(60) particles in solution with the size distribution in the range of 120-140 nm in radius. Humic acid (0 to 10 mg.L-1.promoted the formation of non-aggregated nC(60) in the water, and inhibited aggregation. NOM and IS had jointly affected the size distribution of nC(60). At low concentrations (5 mg.L-1.of NOM, high IS (0.1 mol.L-1.enhanced the formation of smaller nC(60) particles (radius < 120 nm), whereas under high NOM conditions (20 mg.L-1 ., the increase in IS led to disaggregation of nC(60) clusters.
