Abstract:A critical analysis of the available engineered nanomaterials (ENMs) environmental fate modelling approaches indicates that existing tools do not satisfactorily account for the complexities of nanoscale phenomena. Fractal modelling (FM) can complement existing kinetic fate models by including more accurate interpretations of shape and structure, density and collision efficiency parameters to better describe homo- and heteroaggregation. Pathways to including hierarchical symmetry concepts and a route to establi… Show more
“…Existing models are promising but in need of further experimental data and validation, including parameters for fractal modeling . Second order dissolution rate equations have been employed for Ag NPs to capture the initially fast release of Ag ions followed by slower kinetics due to effects such as particle agglomeration .…”
Section: Resultsmentioning
confidence: 99%
“…Estimates of the surface area from theoretical predictions coupled with dissolution experiments of SiO 2 NPs have been done by Vogelsberger et al 44 Existing models are promising but in need of further experimental data and validation, 63 including parameters for fractal modeling. 129 Second order dissolution rate equations have been employed for Ag NPs to capture the initially fast release of Ag ions followed by slower kinetics due to effects such as particle agglomeration. 50 Such second-order equations have in several cases been shown to fit experimental data better compared with first-order equations, 50 but need further validation with respect to experimental data for different kind of NPs.…”
Knowledge on relations between particle
properties and dissolution/transformation
characteristics of metal and metal oxide nanoparticles (NPs) in freshwater
is important for risk assessment and product development. This critical
review aims to elucidate nanospecific effects on dissolution of metallic
NPs in freshwater and similar media. Dissolution rate constants are
compiled and analyzed for NPs of silver (Ag), copper (Cu), copper
oxide/hydroxide (CuO, Cu(OH)2), zinc oxide (ZnO), manganese
(Mn), and aluminum (Al), showing largely varying (orders of magnitude)
constants when modeled using first order kinetics. An effect of small
primary sizes (<15 nm) was observed, leading to increased dissolution
rate constants and solubility in some cases. However, the often extensive
particle agglomeration can result in reduced nanospecific effects
on dissolution and also an increased uncertainty related to the surface
area, a parameter that largely influence the extent of dissolution.
Promising ways to model surface areas of NPs in solution using fractal
dimensions and size distributions are discussed in addition to nanospecific
aspects related to other processes such as corrosion, adsorption of
natural organic matter (NOM), presence of capping agents, and existence
of surface defects. The importance of the experimental design on the
results of dissolution experiments of metal and metal oxide NPs is
moreover highlighted, including the influence of ionic metal solubility
and choice of particle dispersion methodology.
“…Existing models are promising but in need of further experimental data and validation, including parameters for fractal modeling . Second order dissolution rate equations have been employed for Ag NPs to capture the initially fast release of Ag ions followed by slower kinetics due to effects such as particle agglomeration .…”
Section: Resultsmentioning
confidence: 99%
“…Estimates of the surface area from theoretical predictions coupled with dissolution experiments of SiO 2 NPs have been done by Vogelsberger et al 44 Existing models are promising but in need of further experimental data and validation, 63 including parameters for fractal modeling. 129 Second order dissolution rate equations have been employed for Ag NPs to capture the initially fast release of Ag ions followed by slower kinetics due to effects such as particle agglomeration. 50 Such second-order equations have in several cases been shown to fit experimental data better compared with first-order equations, 50 but need further validation with respect to experimental data for different kind of NPs.…”
Knowledge on relations between particle
properties and dissolution/transformation
characteristics of metal and metal oxide nanoparticles (NPs) in freshwater
is important for risk assessment and product development. This critical
review aims to elucidate nanospecific effects on dissolution of metallic
NPs in freshwater and similar media. Dissolution rate constants are
compiled and analyzed for NPs of silver (Ag), copper (Cu), copper
oxide/hydroxide (CuO, Cu(OH)2), zinc oxide (ZnO), manganese
(Mn), and aluminum (Al), showing largely varying (orders of magnitude)
constants when modeled using first order kinetics. An effect of small
primary sizes (<15 nm) was observed, leading to increased dissolution
rate constants and solubility in some cases. However, the often extensive
particle agglomeration can result in reduced nanospecific effects
on dissolution and also an increased uncertainty related to the surface
area, a parameter that largely influence the extent of dissolution.
Promising ways to model surface areas of NPs in solution using fractal
dimensions and size distributions are discussed in addition to nanospecific
aspects related to other processes such as corrosion, adsorption of
natural organic matter (NOM), presence of capping agents, and existence
of surface defects. The importance of the experimental design on the
results of dissolution experiments of metal and metal oxide NPs is
moreover highlighted, including the influence of ionic metal solubility
and choice of particle dispersion methodology.
“…Colloids, which can be defined as particles with any shape and equivalent diameters ranging from 1 to 1000 nm, are ubiquitous in aquatic environments. , Compared with large scale colloids, nanoscale colloids, which have at least one dimension that is less than 100 nm, may have a high reactivity, leading to unexpected human health or environmental hazards. , Due to the profound complexity and heterogeneity of colloids, information on the occurrence, fate and biological effects of nanocolloids is not yet available. , …”
Nanocolloids are widespread in natural water systems, but their characterization and ecological risks are largely unknown. Herein, tangential flow ultrafiltration (TFU) was used to separate and concentrate nanocolloids from surface waters. Unexpectedly, nanocolloids were present in high concentrations ranging from 3.7 to 7.2 mg/L in the surface waters of the Harihe River in Tianjin City, China. Most of the nanocolloids were 10-40 nm in size, contained various trace metals and polycyclic aromatic hydrocarbons, and exhibited fluorescence properties. Envelopment effects and aggregation of Chlorella vulgaris in the presence of nanocolloids were observed. Nanocolloids entered cells and nanocolloid-exposed cells exhibited stronger plasmolysis, chloroplast damage and more starch grains than the control cells. Moreover, nanocolloids inhibited the cell growth, promoted reactive oxygen species (ROS), reduce the chlorophyll a content and increased the cell permeability. The genotoxicity of nanocolloids was also observed. The metabolomics analysis revealed a significant ( p < 0.05) downregulation of amino acids and upregulation of fatty acids contributing to ROS increase, chlorophyll a decrease and plasmolysis. The present work reveals that nanocolloids, which are different from specific, engineered nanoparticles (e.g., Ag nanoparticles), are present at high concentrations, exhibit an obvious toxicity in environments, and deserve more attention in the future.
“…hetero-attachment efficiency) [76] . Furthermore, for a better description of aggregation phenomena, fractal modelling can complement existing kinetic fate models by providing more accurate integration of shape, structure, density and collision efficiency [77] .…”
Highlights
The transparent and systematic reporting of computational models facilitates their regulatory acceptance and use.
A reporting format for physiologically based kinetic, toxicodynamic and environmental fate models was developed.
The QSAR Model Reporting Format (QMRF) was adapted to describe QSARs for nanomaterials.
The model documentation is stored in the publicly accessible JRC Data Catalogue.
The model documentation was used to give an overview of the model landscape for nanomaterials.
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