Potential release scenarios for carbon nanotubes used in composites
TL;DR: It can be concluded that in general, significant release of CNTs from products and articles is unlikely except in manufacturing and subsequent processing, tires, recycling, and potentially in textiles.
About: This article is published in Environment International.The article was published on 2013-09-01 and is currently open access. It has received 214 citations till now.
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TL;DR: This review discusses various enhancement technologies such as the use of ultrasounds for in-process nanoparticles dispersion and of processing aspects to reach optimal properties for using nanocomposites in the selected applications.
Abstract: For the last decades, nanocomposites materials have been widely studied in the scientific literature as they provide substantial properties enhancements, even at low nanoparticles content. Their performance depends on a number of parameters but the nanoparticles dispersion and distribution state remains the key challenge in order to obtain the full nanocomposites’ potential in terms of, e.g., flame retardance, mechanical, barrier and thermal properties, etc., that would allow extending their use in the industry. While the amount of existing research and indeed review papers regarding the formulation of nanocomposites is already significant, after listing the most common applications, this review focuses more in-depth on the properties and materials of relevance in three target sectors: packaging, solar energy and automotive. In terms of advances in the processing of nanocomposites, this review discusses various enhancement technologies such as the use of ultrasounds for in-process nanoparticles dispersion. In the case of nanocoatings, it describes the different conventionally used processes as well as nanoparticles deposition by electro-hydrodynamic processing. All in all, this review gives the basics both in terms of composition and of processing aspects to reach optimal properties for using nanocomposites in the selected applications. As an outlook, up-to-date nanosafety issues are discussed.
514 citations
TL;DR: The goal of this present review is to use knowledge on the life cycle of nano-products to derive possible transformations common ENPs in nano- products may undergo based on how these products will be used by the consumer and eventually discarded.
333 citations
Cites background from "Potential release scenarios for car..."
...Other ENP release and transformation reviews were material specific, such as Ag ENPs (Levard et al., 2012; Reidy et al., 2013), carbon nanotubes (CNTs) (Petersen et al., 2011; Nowack et al., 2013; Köhler et al., 2008) or composite materials (Froggett et al., 2014)....
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..., 2013), carbon nanotubes (CNTs) (Petersen et al., 2011; Nowack et al., 2013; Köhler et al., 2008) or composite materials (Froggett et al....
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TL;DR: The main focus of this review is to explore the maximum applications of CNTs for human health, and it particularly focus on nanocarrier and biomedical applications.
Abstract: Remarkable advances have been achieved in modern material technology, especially in device fabrication, and these have facilitated the use of diverse materials in various applications. Carbon nanotubes (CNTs) are being successfully implemented in drug delivery, sensing, water purification, composite materials, and bone scaffolds. Thus, CNTs must meet a wide range of criteria such as surface modification, high aspect ratio, desired conductivity, high porosity and loading, non-toxicity, specificity, and selectivity, and compatibility for device fabrication. The main focus of this review is to explore the maximum applications of CNTs for human health, and we particularly focus on nanocarrier and biomedical applications. The scope of this review initially covers the basic aspects of CNTs and is also extended further to describe their synthesis strategies as well as various challenges encountered in their functionalization, dispersion, and toxicity. Our discussion also emphasizes future directions for these emerging fields of research.
302 citations
TL;DR: Evaluated studies with both positive and negative effects of different carbon nano-materials on terrestrial plants and associated soil-dwelling microbes highlight critical knowledge gaps, including the need for more soil-based investigations under environmentally relevant conditions.
Abstract: There has been great interest in the use of carbon nano-materials (CNMs) in agriculture. However, the existing literature reveals mixed effects from CNM exposure on plants, ranging from enhanced crop yield to acute cytotoxicity and genetic alteration. These seemingly inconsistent research-outcomes, taken with the current technological limitations for in situ CNM detection, present significant hurdles to the wide scale use of CNMs in agriculture. The objective of this review is to evaluate the current literature, including studies with both positive and negative effects of different CNMs (e.g., carbon nano-tubes, fullerenes, carbon nanoparticles, and carbon nano-horns, among others) on terrestrial plants and associated soil-dwelling microbes. The effects of CNMs on the uptake of various co-contaminants will also be discussed. Last, we highlight critical knowledge gaps, including the need for more soil-based investigations under environmentally relevant conditions. In addition, efforts need to be focused on better understanding of the underlying mechanism of CNM-plant interactions.
245 citations
Cites background from "Potential release scenarios for car..."
...Importantly, CNM stability and transport will not only depend on native material properties but also on the characteristics of any conjugated composites and on the surrounding conditions (Nowack et al., 2013)....
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...Nowack et al. (2013) suggested that the predominant release pathway is during initial synthesis and handling of ENMs, which will result in occupational exposure and perhaps large-scale environmental exposure if an accidental release occurs....
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...Due to lack of specific regulations for ENM disposal, CNMs composites are often incinerated, and the formation of aerosols or air borne particles containing the CNTs is possible (Petersen et al., 2011; Nowack et al., 2013)....
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TL;DR: It is the aim of this Review to critically compare naturally observed processes with those found for engineered systems to identify the "nanospecific" properties of manufactured particles and describe critical knowledge gaps relevant for the risk assessment of manufactured nanomaterials in the environment.
Abstract: The production and use of nanoparticles leads to the emission of manufactured or engineered nanoparticles into the environment. Those particles undergo many possible reactions and interactions in the environment they are exposed to. These reactions and the resulting behavior and fate of nanoparticles in the environment have been studied for decades through naturally occurring nanoparticulate (1–100 nm) and colloidal (1–1000 nm) substances. The knowledge gained from these investigations is nowhere near sufficiently complete to create a detailed model of the behavior and fate of engineered nanoparticles in the environment, but is a valuable starting point for the risk assessment of these novel materials. It is the aim of this Review to critically compare naturally observed processes with those found for engineered systems to identify the “nanospecific” properties of manufactured particles and describe critical knowledge gaps relevant for the risk assessment of manufactured nanomaterials in the environment.
234 citations
References
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TL;DR: The results of this study indicate that risks to aquatic organisms may currently emanate from nano- Ag, nano-TiO(2), and nano-ZnO in sewage treatment effluents for all considered regions and for nano-Ag in surface waters.
Abstract: Engineered nanomaterials (ENM) are already used in many products and consequently released into environmental compartments. In this study, we calculated predicted environmental concentrations (PEC) based on a probabilistic material flow analysis from a life-cycle perspective of ENM-containing products. We modeled nano-TiO2, nano-ZnO, nano-Ag, carbon nanotubes (CNT), and fullerenes for the U.S., Europe and Switzerland. The environmental concentrations were calculated as probabilistic density functions and were compared to data from ecotoxicological studies. The simulated modes (most frequent values) range from 0.003 ng L−1 (fullerenes) to 21 ng L−1 (nano-TiO2) for surface waters and from 4 ng L−1 (fullerenes) to 4 μg L−1 (nano-TiO2) for sewage treatment effluents. For Europe and the U.S., the annual increase of ENMs on sludge-treated soil ranges from 1 ng kg−1 for fullerenes to 89 μg kg−1 for nano-TiO2. The results of this study indicate that risks to aquatic organisms may currently emanate from nano-Ag, n...
2,258 citations
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...
1,703 citations
"Potential release scenarios for car..." refers background in this paper
...The release of inorganic nanomaterials from textiles during washing has been reported in several papers (Benn and Westerhoff, 2008; Geranio et al., 2009; Lorenz et al., 2012; Windler et al., 2012)....
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...Most studies were carried out with nano-Ag and found significant release into the washwater both as dissolved and particulate Ag (Benn and Westerhoff, 2008; Geranio et al., 2009; Lorenz et al., 2012)....
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TL;DR: The thermal stability and flame retardancy of polyurethanes is reviewed in this article, where a detailed description of TGA, TGA-MS and TGAFTIR methods for studying the decomposition mechanism and kinetics is also provided.
1,329 citations
"Potential release scenarios for car..." refers background in this paper
...In Australia, about 70% of MSW has been directed to landfills without pre-treatment in 2002 (Chattopadhyay and Webster, 2009)....
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TL;DR: Results show that much of the ENM released from products is present in matrix-bound form, but that also some fraction is released as single, dispersed nanoparticles, which is important to investigate in what form ENM are released.
Abstract: There is scientific agreement that engineered nanomaterial (ENM) production, use and disposal lead to environmental release of ENM. However, very little is known on emissions of ENM to the environment. Currently, techniques are lacking to quantitatively monitor ENM emissions to and concentrations in the environment, and hence data on emissions and environmental concentrations are scarce. One of the few available studies reports the detection of nano-TiO2 in water leaching from exterior facades. Some experimental evidence is available on the release of nanosized materials from commercial textiles during washing. A handful of modeling studies have investigated ENM release to the environment. These studies modeled either the release of ENMs to the environment from ENM containing products during the consumer usage, or the release throughout the whole life cycle of ENM and ENM-containing products. Sewage sludge, wastewater, and waste incineration of products containing ENM were shown to be the major flows through which ENMs end up in the environment. However, reliable data are particularly lacking on release during ENM production and on the application amounts and empirical information on release coefficients for all life cycle stages and environmental compartments. Quantitative data linking occupational exposure measurements and ENM emission flows into the environment are almost completely missing. Besides knowing the amounts of ENM released into the environment, it is equally important to investigate in what form ENMs are released. First results show that much of the ENM released from products is present in matrix-bound form, but that also some fraction is released as single, dispersed nanoparticles.
720 citations
"Potential release scenarios for car..." refers background in this paper
...The prospective widespread usage of carbon nanotubes (CNTs) in industrial applications and consumer products and articles creates the potential for release of CNTs that could result in a possible increase of human and environmental exposure to CNTs (Gottschalk and Nowack, 2011; Koehler et al., 2008)....
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...…prospective widespread usage of carbon nanotubes (CNTs) in industrial applications and consumer products and articles creates the potential for release of CNTs that could result in a possible increase of human and environmental exposure to CNTs (Gottschalk and Nowack, 2011; Koehler et al., 2008)....
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TL;DR: The results show that under conditions relevant to washing, primarily coarse Ag-containing particles are released, similar to previous studies of nano-Ag.
Abstract: The widespread use of silver nanoparticles (Ag-NPs) in commercial products, especially textiles, will likely result in an unknown spread of Ag into the environment. The quantification and characterization of the Ag released from nano-Ag-products is an important parameter needed to predict the effect of Ag-NPs on the environment. The aim of this study was to determine the amount and the form of Ag released during washing from nine fabrics with different ways of silver incorporation into or onto the fibers. The effect of pH, surfactants, and oxidizing agents was evaluated. The results show that little dissolution of Ag-NPs occurs under conditions relevant to washing (pH 10) with dissolved concentrations 10 times lower than at pH 7. However, bleaching agents such as hydrogen peroxide or peracetic acid (formed by the perborate/TAED system) can greatly accelerate the dissolution of Ag. The amount and form of Ag released from the fabrics as ionic and particulate Ag depended on the type of Ag-incorporation into the textile. The percentage of the total silver emitted during one washing of the textiles varied considerably among products (from less than 1 to 45%). In the washing machine the majority of the Ag (at least 50% but mostly >75%) was released in the size fraction >450 nm, indicating the dominant role of mechanical stress. A conventional silver textile did not show any significant difference in the size distribution of the released silver compared to many of the textiles containing nano-Ag. These results have important implications for the risk assessment of Ag-textiles and also for environmental fate studies of nano-Ag, because they show that under conditions relevant to washing, primarily coarse Ag-containing particles are released.
608 citations
"Potential release scenarios for car..." refers background in this paper
...Most of the silver-textiles were alsomade using a finishing process and therefore the nano-Ag was only bound to the fiber surface and thus susceptible to release whereas fibers with nano-Ag embedded in the fiber released much lower amounts (Geranio et al., 2009)....
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...The release of inorganic nanomaterials from textiles during washing has been reported in several papers (Benn and Westerhoff, 2008; Geranio et al., 2009; Lorenz et al., 2012; Windler et al., 2012)....
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...Most studies were carried out with nano-Ag and found significant release into the washwater both as dissolved and particulate Ag (Benn and Westerhoff, 2008; Geranio et al., 2009; Lorenz et al., 2012)....
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