Overview of Nanoscience in the Environment - Environmental and Human Health Impacts of Nanotechnology - page 22

200 nm

(a) (b)

14 12

12

10

10

8

8

6

6

4

4

2

2

0 0

0 5 10 15

Equivelent circular diameter (nm)

0 5 10 15 20

AFM height (nm)

(c) (d)

3200 80

70

2400 60

50

40

1600

30

20

800

10

0

0

pH 2 pH 3 pH 4 pH 5

0 5 10 15 20 25

(e) (f) Hydrodynamic diameter (nm) pH

Figure 1.5 Characterization of iron oxide nanoparticles (200 mg L − 1 Fe) reference solution:
(a) transmission electronic microscopy (TEM) micrograph; (b) atomic force microscopy
(AFM) micrograph; (c) equivalent circular diameter histogram calculated from TEM micro-
graph; (d) particles height histogram measured by AFM; (e) hydrodynamic diameter for iron
oxide nanoparticles at pH 2 in the absence of humic acid measured by fl ow-fi eld fl ow frac-
tionation; (f ) Concentration of dissolved iron in the iron oxide suspension at variable pH
values. (M. Baalousha, A. Manciulea, S. Cumberland et al. , Aggregation and surface proper-
ties of iron oxide nanoparticles; infl uence of pH and natural organic matter, Environmental
Toxicology & Chemistry , 2008, 27 , 1875-82. Reproduced with permission from Allen Press
Publishing Services.)