Analysis and Characterization of Manufactured Nanoparticles in Aquatic Environments - Environmental and Human Health Impacts of Nanotechnology - page 211

Agglomeregation State Concentration Shape

Surface
Speciation

Size

Surface
Charge

+

+

+

+

+

Surface
Functionality

Size
Distribution

Porosity /
Surface Area

Structure /
Crystallinity

Composition

Figure 6.1 The important properties of manufactured nanoparticles in aqueous media are
shown, indicating that the central concept of a homogeneous solid sphere with a clean
surface is often an over-simplifi cation. All or several of these properties are needed to under-
stand the fate and behaviour of these nanoparticles in the environment or to characterize a
certain ecotoxicology experiment. Therefore, a combination of analytical methods is required
to obtain a complete characterization. (Figure partly adopted from Tinke et al. , 2006.)
(See colour plate section for a colour representation)

sites (Chapter 3 (this volume); Waychunas et al. , 2005 ; Wigginton et al. , 2007a ;
Madden and Hochella, 2005), and therefore it is essential to be able to characterize
these properties as a function of size.
Particle size is the most common property used to describe a particle but it is
only for perfect, compact spheres that size is a trivial descriptor (only one value
required). For irregularly shaped particles equivalent spherical diameters (ESD)
have to be used (Jennings and Parslow, 1988) (Table 6.2). Different particle ESD
could be of varying signifi cance in different process studies. More importantly, the
different methods discussed later in this section apply to specifi c ESD. Therefore,
such methods can not provide directly comparable numbers. There is an extensive
literature available on the fundamental aspects of particle size analysis (Barth and
Flippen, 1995; Webb, 2008) and, although they cover only larger particles ( ∼ 0.1 µ m

and above), much can be learned from these and applied also to NPs.