Florian Part

Current limitations and challenges in nanowaste detection, characterisation and monitoring.

Engineered nanomaterials (ENMs) are already extensively used in diverse consumer products. Along the life cycle of a nano-enabled product, ENMs can be released and subsequently accumulate in the environment. Material flow models also indicate that a variety of ENMs may accumulate in waste streams. Therefore, a new type of waste, so-called nanowaste, is generated when end-of-life ENMs and nano-enabled products are disposed of. In terms of the precautionary principle, environmental monitoring of end-of-life ENMs is crucial to allow assessment of the potential impact of nanowaste on our ecosystem. Trace analysis and quantification of nanoparticulate species is very challenging because of the variety of ENM types that are used in products and low concentrations of nanowaste expected in complex environmental media. In the framework of this paper, challenges in nanowaste characterisation and appropriate analytical techniques which can be applied to nanowaste analysis are summarised. Recent case studies focussing on the characterisation of ENMs in waste streams are discussed. Most studies aim to investigate the fate of nanowaste during incineration, particularly considering aerosol measurements; whereas, detailed studies focusing on the potential release of nanowaste during waste recycling processes are currently not available. In terms of suitable analytical methods, separation techniques coupled to spectrometry-based methods are promising tools to detect nanowaste and determine particle size distribution in liquid waste samples. Standardised leaching protocols can be applied to generate soluble fractions stemming from solid wastes, while micro- and ultrafiltration can be used to enrich nanoparticulate species. Imaging techniques combined with X-ray-based methods are powerful tools for determining particle size, morphology and screening elemental composition. However, quantification of nanowaste is currently hampered due to the problem to differentiate engineered from naturally-occurring nanoparticles. A promising approach to face these challenges in nanowaste characterisation might be the application of nanotracers with unique optical properties, elemental or isotopic fingerprints. At present, there is also a need to develop and standardise analytical protocols regarding nanowaste sampling, separation and quantification. In general, more experimental studies are needed to examine the fate and transport of ENMs in waste streams and to deduce transfer coefficients, respectively to develop reliable material flow models.

Traceability of fluorescent engineered nanomaterials and their fate in complex liquid waste matrices.

The number of products containing engineered nanomaterials (ENMs) has increased due to their high industrial relevance as well as their use in diverse consumer products. At the end of their life cycle ENMs might be released to the environment and therefore concerns arise regarding their environmental impact. In order to track their fate upon disposal, it is crucial to establish methods to trace ENMs in complex environmental samples and to differentiate them from naturally-occurring nanoparticles. The goal of this study was to distinctively trace ENMs by (non-invasive) detection methods. For this, fluorescent ENMs, namely quantum dots (QDs), were distinctively traced in complex aqueous matrices, and were still detectable after a period of two months using fluorescence spectroscopy. In particular, two water-dispersible QD-species, namely CdTe/CdS QDs with N-acetyl-l-cysteine as capping agent (NAC-QDs) and surfactant-stabilized CdSe/ZnS QDs (Brij(®)58-QDs), were synthesized to examine their environmental fate during disposal as well as their potential interaction with naturally-occurring substances present in landfill leachates. When QDs were spiked into a leachate from an old landfill site, alteration processes, such as sorption, aggregation, agglomeration, and interactions with dissolved organic carbon (DOC), led to modifications of the optical properties of QDs. The spectral signatures of NAC-QDs deteriorated depending on residence time and storage temperature, while Brij(®)58-QDs retained their photoluminescence fingerprints, indicating their high colloidal stability. The observed change in photoluminescence intensity was mainly caused by DOC-interaction and association with complexing agents, such as fulvic or humic acids, typically present in mature landfill leachates. For both QD-species, the results also indicated that pH of the leachate had no significant impact on their optical properties. As a result, the unique spectroscopic fingerprints of QDs, specifically surfactant-stabilized QDs, allowed distinctive tracing in complex aqueous waste matrices in order to study their long-term behavior and ultimate fate.

A review of the fate of engineered nanomaterials in municipal solid waste streams

Significant knowledge and data gaps associated with the fate of product-embedded engineered nanomaterials (ENMs) in waste management processes exist that limit our current ability to develop appropriate end-of-life management strategies. This review paper was developed as part of the activities of the IWWG ENMs in Waste Task Group. The specific objectives of this review paper are to assess the current knowledge associated with the fate of ENMs in commonly used waste management processes, including key processes and mechanisms associated with ENM fate and transport in each waste management process, and to use that information to identify the data gaps and research needs in this area. Literature associated with the fate of ENMs in wastes was reviewed and summarized. Overall, results from this literature review indicate a need for continued research in this area. No work has been conducted to quantify ENMs present in discarded materials and an understanding of ENM release from consumer products under conditions representative of those found in relevant waste management process is needed. Results also indicate that significant knowledge gaps associated with ENM behaviour exist for each waste management process investigated. There is a need for additional research investigating the fate of different types of ENMs at larger concentration ranges with different surface chemistries. Understanding how changes in treatment process operation may influence ENM fate is also needed. A series of specific research questions associated with the fate of ENMs during the management of ENM-containing wastes have been identified and used to direct future research in this area.

Modeling the fate and end-of-life phase of engineered nanomaterials in the Japanese construction sector

To date construction materials that contain engineered nanomaterials (ENMs) are available at the markets, but at the same time very little is known about their environmental fate. Therefore, this study aimed at modeling the potential fate of ENMs by using the example of the Japanese construction sector and by conducting a dynamic material flow analysis. Expert interviews and national reports revealed that about 3920-4660 tons of ENMs are annually used for construction materials in Japan. Nanoscale TiO2, SiO2, Al2O3 and carbon black have already been applied for decades to wall paints, road markings or concrete. The dynamic material flow model indicates that in 2016 about 95% of ENMs, which have been used since their year of market penetration, remained in buildings, whereas only 5% ended up in the Japanese waste management system or were diffusely released into the environment. Considering the current Japanese waste management system, ENMs were predicted to end up in recycled materials (40-47%) or in landfills (36-41%). It was estimated that only a small proportion was used in agriculture (5-7%, as ENM-containing sewage sludges) or was diffusely released into soils, surface waters or the atmosphere (5-19%). The results indicate that ENM release predominantly depend on their specific applications and characteristics. The model also highlights the importance of adequate collection and treatment of ENM-containing wastes. In future, similar dynamic flow models for other countries should consider, inasmuch as available, historical data on ENM production (e.g. like declaration reports that are annually published by relevant public authorities or associations), as such input data is very important regarding data reliability in order to decrease uncertainties and to continuously improve model accuracy. In addition, more environmental monitoring studies that aim at the quantification of ENM release and inadvertent transfer, particularly triggered by waste treatment processes, would be needed in order to validate such models.

Preparation of water-soluble, PEGylated, mixed-dispersant quantum dots, with a preserved photoluminescence quantum yield

High quantum yields, colloidal stability and surfaces amenable to diverse chemical modifications are critical objectives for quantum dot (QD) synthesis. We present an approach of QD preparation developed for achieving these criteria. In addition, the nascent QDs are already water-soluble. We then partially exchanged the N-acetyl cysteine (NAC) ligands on our core–shell–shell CdTe/CdS/ZnS QDs for dithiol-poly(ethylene glycol) (dithiol-PEG). This resulted in mixed-dispersant QDs with photoluminescence properties rivaling those of QDs synthesized under high temperature conditions and modified by ligand exchange using dithiol-PEG. Optimization of the dithiol-PEG adsorption conditions not only retained efficient surface passivation by NAC as well as luminescence properties, but also resulted in sufficiently dense PEG-grafting to confer strong colloidal stability. Since particle properties such as solubility and protein resistance critically depend on the PEG conformation and density, we also evaluated the effects of various adsorption and grafting conditions on the polymer, using ATR-FTIR and TGA analysis. Leakage of cadmium ions from the core is prevented by the ZnS-shell, which is stabilized by the remnant NAC and physicochemically shielded by the PEG-layer. Furthermore, the residual NAC has carboxylic groups that can in principle still be chemically-modified with diverse functional groups. These characteristics, particularly their excellent solubility in water, render our QDs compatible for use in biomedical and environmental applications.

Corrigendum to “Supplementary material – Traceability of fluorescent engineered nanomaterials and their fate in complex liquid waste matrices” [Environ. Pollut. 214 (July 2016), 795–805]

Corrigendum to “Supplementary material e Traceability of fluorescent engineered nanomaterials and their fate in complex liquid waste matrices” [Environ. Pollut. 214 (July 2016), 795e805] Florian Part a, , Christoph Zaba , Oliver Bixner , Christian Zafiu , Stephan Hann , Eva-Kathrin Sinner b, , Marion Huber-Humer a a Department of Water-Atmosphere-Environment, Institute of Waste Management, University of Natural Resources and Life Sciences, Muthgasse 107, 1190 Vienna, Austria b Department of Nanobiotechnology, Institute for Synthetic Bioarchitectures, University of Natural Resources and Life Sciences, Muthgasse 11, 1190 Vienna, Austria c ICS-6 Structure Biochemistry, Forschungszentrum Jülich, Wilhelm-Johnen-Straße, 52425 Jülich, Germany d Department of Chemistry, Division of Analytical Chemistry, University of Natural Resources and Life Sciences, Muthgasse 18, 1190 Vienna, Austria

Environmentally relevant aspects of nanomaterials at the end of the use phase – Part I: Wastewater and sewage sludge (NanoTrust dossier No. 043en – February 2015)

Synthetically produced nanomaterials (Engineered Nanomaterials – ENMs) can potentially be released along the entire lifecycle of a product. The use of products with suspended ENMs, such as sunscreen lotions, almost certainly leads to an immediate environmental input. In contrast, ENMs that are solidly integrated in a product matrix can only be released by mechanical and/or chemical processes. ENMs can enter the environment either directly or indirectly (e.g. during the disposal phase), where both their properties and environmental conditions can determine their aggregation behavior. Weathering experiments with facade paints show that only a very small proportion of the contained titanium dioxide nanoparticles (TiO2-NPs) are released. In paints with silver nanoparticles (Ag-NPs), however, up to 30% of the particles can leach out over time. In the case of textiles treated with Ag-NPs, up to 10% of the silver contents can be washed out and enter the wastewater. Tests show that Ag-NPs can be transported over long distances in sewers without deposition. These are partly transformed into water-insoluble silver sulfide. Up to 85% of the TiO2-NPs and up to 99% of the Ag-NPs are removed via sewage sludge during waste water treatment, whereby Ag-NPs and other silver forms are transformed into water-insoluble silver chloride and -sulfide. Once ENMs enter surface waters, a differentiation between natural and engineered nanoparticles becomes complicated. Studies on TiO2-NPs, which can enter swimming waters via sunscreen lotions, show that these aggregate quickly and can subsequently be measured in the sediment.

Umweltrelevante Aspekte von Nanomaterialien am Ende der Nutzungsphase – Teil II: Abfallverwertung und -entsorgung (NanoTrust-Dossier Nr. 044 – April 2015)

Kunstlich hergestellte Nanomaterialien (ENM) konnen potenziell wahrend aller Abfallbehandlungsprozesse freigesetzt werden sowie in Reststoffen, Altstoffen, Sekundarrohstoffen oder Komposten akkumulieren. Zum Verbleib und Verhalten von ENM wahrend der Abfallverwertung und -entsorgung liegen jedoch erst wenige Untersuchungen vor. In Osterreich werden mehr als die Halfte des in Haushalten anfallenden Abfalls getrennt gesammelt und als Altstoff, biogene Abfalle sowie Problemstoffe und Elektroaltgerate weiterbehandelt. Der Rest wird entweder in Mullverbrennungsanlagen (MVA) oder in mechanisch-biologischen Abfallbehandlungsanlagen (MBA) behandelt. Erste Untersuchungen in MVAs zeigen, dass sich thermisch stabile ENM (Metalloxide) uberwiegend in den festen Ruckstanden (Schlacke, Flugasche) anreichern. In Osterreich werden diese uberwiegend in Reststoffdeponien abgelagert. ENM konnen auch wahrend des Recyclings von Produkten wieder freigesetzt werden (etwa Quantum Dots aus LEDs von Elektroaltgeraten oder CNTs aus Verbundmaterialien). Nanosilber scheint sich beim Recycling negativ auf die mechanischen Eigenschaften von Kunststoffen auszuwirken. ENM konnen direkt als Produktionsabfalle oder als Bestandteil von „Nano-Produkten“ bzw. als Sekundarabfalle, wie ENM-haltige Klarschlamme oder Verbrennungsruckst.nde, deponiert werden. Es wird geschatzt, dass weltweit zwischen 60 bis 86 % der am haufigsten eingesetzten ENM in Deponien landen. Da die Einsatzgebiete von ENM sehr mannigfaltig sind und deren Schicksal in der Umwelt im Einzelfall sehr unterschiedlich sein kann, konnen noch keine verallgemeinerten Aussagen getroffen werden.