Effect of monovalent and divalent cations, anions and fulvic acid on aggregation of citrate-coated silver nanoparticles
01 Jun 2013-Science of The Total Environment (SCIENCE OF THE TOTAL ENVIRONMENT)-Vol. 454455, pp 119-131
TL;DR: An empirical formula is proposed that reproduces the effect of mixtures of electrolytes in the presence of humic substances and cations that can be used to help predict the aggregation behavior of cit-AgNPs in environmental and ecotoxicological media.
About: This article is published in Science of The Total Environment.The article was published on 2013-06-01. It has received 246 citations till now. The article focuses on the topics: Electrolyte & Dynamic light scattering.
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TL;DR: In this paper, the main parameters that will affect the surface state of nanoparticles and their influence on antimicrobial efficacy are reviewed and an analysis of several works on Ag NPs activity, observed through the scope of an oxidative Ag+ release.
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TL;DR: If traditional approaches based on the DLVO-theory can be useful in specific cases, quantitative aggregation models taking into account DOM dynamics, bridging, and disaggregation are needed for a comprehensive modeling of colloids stability in natural media.
Abstract: This contribution critically reviews the state of knowledge on interactions of natural colloids and engineered nanoparticles with natural dissolved organic materials (DOM). These interactions determine the behavior and impact of colloids in natural system. Humic substances, polysaccharides, and proteins present in natural waters adsorb onto the surface of most colloids. We outline major adsorption mechanisms and structures of adsorption layers reported in the literature and discuss their generality on the basis of particle type, DOM type, and media composition. Advanced characterization methods of both DOM and colloids are needed to address insufficiently understood aspects as DOM fractionation upon adsorption, adsorption reversibility, and effect of capping agent. Precise knowledge on adsorption layer helps in predicting the colloidal stability of the sorbent. While humic substances tend to decrease aggregation and deposition through electrostatic and steric effects, bridging-flocculation can occur in th...
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TL;DR: Recent achievements in the field of nano-ecotoxicology in both aquatic and terrestrial systems are highlighted but also substantial gaps that require further attention in the future are referred to.
Abstract: Nanoparticles serve various industrial and domestic purposes which is reflected in their steadily increasing production volume. This economic success comes along with their presence in the environment and the risk of potentially adverse effects in natural systems. Over the last decade, substantial progress regarding the understanding of sources, fate, and effects of nanoparticles has been made. Predictions of environmental concentrations based on modelling approaches could recently be confirmed by measured concentrations in the field. Nonetheless, analytical techniques are, as covered elsewhere, still under development to more efficiently and reliably characterize and quantify nanoparticles, as well as to detect them in complex environmental matrixes. Simultaneously, the effects of nanoparticles on aquatic and terrestrial systems have received increasing attention. While the debate on the relevance of nanoparticle-released metal ions for their toxicity is still ongoing, it is a re-occurring phenomenon that inert nanoparticles are able to interact with biota through physical pathways such as biological surface coating. This among others interferes with the growth and behaviour of exposed organisms. Moreover, co-occurring contaminants interact with nanoparticles. There is multiple evidence suggesting nanoparticles as a sink for organic and inorganic co-contaminants. On the other hand, in the presence of nanoparticles, repeatedly an elevated effect on the test species induced by the co-contaminants has been reported. In this paper, we highlight recent achievements in the field of nano-ecotoxicology in both aquatic and terrestrial systems but also refer to substantial gaps that require further attention in the future.
529 citations
Cites background from "Effect of monovalent and divalent c..."
...Furthermore, multivalent cations are more efficient than monovalent cations [97], whereas the efficiency within both groups of cations depends on their respective identity as judged by critical coagulation concentrations (CCCs): the aggregation of citrate-coated Ag NP was, for instance, more efficient for Ca2+ than Mg2+ [76], which may be explained by the higher ability of Ca2+ to form citrate complexes [98]....
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TL;DR: An exhaustive examination of current research trends with a focus on nanomaterials (NMs) to considerably improve the performance of classical wastewater treatment technologies, e.g. adsorption, catalysis, separation, and disinfection is undertaken.
Abstract: The efficient handling of wastewater pollutants is a must, since they are continuously defiling limited fresh water resources, seriously affecting the terrestrial, aquatic, and aerial flora and fauna. Our vision is to undertake an exhaustive examination of current research trends with a focus on nanomaterials (NMs) to considerably improve the performance of classical wastewater treatment technologies, e.g. adsorption, catalysis, separation, and disinfection. Additionally, NM-based sensor technologies are considered, since they have been significantly used for monitoring water contaminants. We also suggest future directions to inform investigators of potentially disruptive NM technologies that have to be investigated in more detail. The fate and environmental transformations of NMs, which need to be addressed before large-scale implementation of NMs for water purification, are also highlighted.
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References
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TL;DR: The results of this study make it possible for the first time to carry out a quantitative risk assessment of nanoparticles in the environment and suggest further detailed studies of nano-TiO2.
Abstract: The aim of this study was to use a life-cycle perspective to model the quantities of engineered nanoparticles released into the environment. Three types of nanoparticles were studied: nano silver (nano-Ag), nano TiO2 (nano-TiO2), and carbon nanotubes (CNT). The quantification was based on a substance flow analysis from products to air, soil, and water in Switzerland. The following parameters were used as model inputs: estimated worldwide production volume, allocation of the production volume to product categories, particle release from products, and flow coefficients within the environmental compartments. The predicted environmental concentrations (PEC) were then compared to the predicted no effect concentrations (PNEC) derived from the literature to estimate a possible risk. The expected concentrations of the three nanoparticles in the different environmental compartments vary widely, caused by the different life cycles of the nanoparticle-containing products. The PEC values for nano-TiO2 in water are 0....
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TL;DR: Variable leaching rates among sock types suggests that the sock manufacturing process may control the release of silver, and physical separation and ion selective electrode (ISE) analyses suggest that both colloidal and ionic silver leach from the socks.
Abstract: Manufacturers of clothing articles employ nanosilver (n-Ag) as an antimicrobial agent, but the environmental impacts of n-Ag release from commercial products are unknown. The quantity and form of the nanomaterials released from consumer products should be determined to assess the environmental risks of nanotechnology. This paper investigates silver released from commercial clothing (socks) into water, and its fate in wastewater treatment plants (WWTPs). Six types of socks contained up to a maximum of 1360 µg-Ag/g-sock and leached as much as 650 µg of silver in 500 mL of distilled water. Microscopy conducted on sock material and wash water revealed the presence of silver particles from 10 to 500 nm in diameter. Physical separation and ion selective electrode (ISE) analyses suggest that both colloidal and ionic silver leach from the socks. Variable leaching rates among sock types suggests that the sock manufacturing process may control the release of silver. The adsorption of the leached silver to WWTP biom...
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TL;DR: An empirical kinetic law is proposed that reproduces the observed effects of dissolution time, pH, humic/fulvic acid content, and temperature observed here in the low range of nanosilver concentration most relevant for the environment.
Abstract: Many important aspects of nanosilver behavior are influenced by the ionic activity associated with the particle suspension, including antibacterial potency, eukaryotic toxicity, environmental release, and particle persistence. The present study synthesizes pure, ion-free, citrate-stabilized nanosilver (nAg) colloids as model systems, and measures their time-dependent release of dissolved silver using centrifugal ultrafiltration and atomic absorption spectroscopy. Ion release is shown to be a cooperative oxidation process requiring both dissolved dioxygen and protons. It produces peroxide intermediates, and proceeds to complete reactive dissolution under some conditions. Ion release rates increase with temperature in the range 0−37 °C, and decrease with increasing pH or addition of humic or fulvic acids. Sea salts have only a minor effect on dissolved silver release. Silver nanoparticle surfaces can adsorb Ag+, so even simple colloids contain three forms of silver: Ag0 solids, free Ag+ or its complexes, an...
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TL;DR: The surface properties of ENPs are of essential importance for their aggregation behavior, and thus for their mobility in aquatic and terrestrial systems and for their interactions with algae, plants and, fungi as mentioned in this paper.
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