Table 1.
Chemical composition and pH of OECD surface water.
Fig 1.
TEM images of the studied NPs.
a: Zn NPs, b: Cu NPs, c: Ag NPs.
Fig 2.
Zeta potential intensity distributions for three separate measurements of 10 nm citrate coated AgNPs (particle concentration: 10 μg mL-1) in (a) 10 mM NaCl and (b) 150 mM NaCl, with intensity (kcounts s-1) on the y-axis and zeta potential (mV) plus electrophoretic mobility (μmcmV-1s-1) on the x-axes.
The different curves represent three consecutive measurements of the same sample. The zeta potentials were determined using the Smoluschowski approximation.
Fig 3.
Particle size distribution measurements (volume) by means of PCCS of citrate-capped Ag NPs in 10 mM and 150 mM NaCl, respectively.
Fig 4.
Plot illustrating the effect of particle/agglomerate size on Henry’s function f(κ·a) for NaCl solutions with 10 and 150 mM ionic strengths using the Ohshima correction (Eqs 3 and 4).
Table 2.
Variations in f(κ·a) and zeta potential with changing particle size and ionic strength according to the Ohshima correction[7, 35] using values for Ag NPs in NaCl (Fig 3) compared with the Smoluschowski (κ·a>>1, f(κ·a) = 1.5) and the Hückel (κ·a<<1, f(κ·a) = 1) models.
[35].
Fig 5.
ZP intensity distributions in blank solutions without any particles: (a) cell media (BEGM) and (b) 10 mM NaCl, and corresponding intensity distributions in the same solutions with citrate-capped AgNPs: (c) cell media (BEGM) and (d) 10 mM NaCl.
For the blank samples (a) and (b), average values of three independent measurements are shown, whereas corresponding three independent measurements are shown for the samples that contain particles, (c) and (d).
Fig 6.
Particle size distribution (volume) of citrate-capped Ag NPs in BEGM cell media.
Data from [24].
Fig 7.
Fraction of released Zn, determined by means of AAS, compared to the total amount of Zn (added as Zn NPs: 10 mg L-1 and 100 mg L-1) in synthetic surface water after 15, 30 and 60 min of exposure.
Fig 8.
Simulation of changes in Henry’s function (κ·a), Eq 3, as a function of the fraction of metal release compared with the total amount of metal in the added Me NPs (0.1 gL-1) of two different particle sizes, a) Ø 10 nm and b) 1000 nm, in dispersion media of different ionic strength (0.1, 1, 150 mM).
Fig 9.
Particle size distribution (a) and scattered light intensity (b), as depicted by means of PCCS, of Zn NPs in synthetic surface water (10 mgL-1) after 1, 15, 30 and 60 min of exposure.
Table 3.
XPS data on Cu 2p and O 1s for dry, sonicated, and non-sonicated Cu NPs.