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Mikroplastik Detektion mit Thermoanalytischen Methoden: Analytik, Referenzmaterial, Ringversuche
(2024)
Ich dem Vortrag geht es um die Vorstellung von thermoanalytischen Methoden für die Mikroplastik-Detektion. Verschiedene Kopplungsmöglichkeiten werden gezeigt und die Funktionsweise der TED-GC/MS wird erklärt. Im zweiten Teil werden Referenzmaterialien für die Mikroplastik-Analytik diskutiert. PET -Tabletten des PlasticTrace Projektes werden vorgestellt. Am Ende wird der VAMAS Ringversuch zur Mikroplastik-Detektion gezeigt.
Monitoring of microplastics in food matrices is crucial to determinate the human exposure. By direct ingestion microplastics could be released in the food during the production, through packaging and by consumer’s use. The absence of standard methods to quantify and detect different size range and type of microplastics has led to difficult and time consuming procedural steps, poor accuracy and lack of comparability. In this work, matrix characterization and laboratory experiments were used to investigate the efficiency of sample preparation in milk powder. This information is crucial to compile a standard procedure for sample preparation and digestion of common milk powder to detect different particle sizes and types of polymers. Charaterisation is done by TGA and TOC measurements.
Following the recommendation of the European Chemicals Agency, on 25 September 2023 the European Commission passed a comprehensive new regulation to reduce emissions of microplastics (MP) into the environment, which includes the sale and use of intentionally added MP.1,2 This also applies to the application of synthetic rubber granulate infill in artificial turf systems and will ultimately have an impact on recreational sports. In Germany, rubber granulate made of ethylene-propylene-diene-monomer rubber (EPDM) is currently predominantly used. So far, there is no sufficient database for estimating MP emissions from artificial turf pitches into the environment and thus their relevance as a source of MP pollution.3 This topic is controversially discussed due to the complexity of sampling and analytics. To close this research gap, this project has the goal to determine mass balances for the emissions of MP from artificial turf pitches to allow an estimation of the amount of MP released per artificial turf pitch and year.
Within this study, MP emissions of three artificial turf scenarios at different time states (unaged, artificially aged and real-time aged) are compared: the past (old turf: fossil based, synthetic infill), present (most commonly installed in Europe: fossil based, EPDM infill), and the future (turf with recycled gras fibres, no synthetic infill). To simulate the outdoor weathering during the lifespan of an artificial turf of approx. 15 years, brand-new artificial turf and EPDM rubber granulate were accelerated aged by means of UV weathering and mechanical stress. Potential MP emissions into surface and groundwater are simulated by lysimeter and shake experiments. MP mass contents are subsequently determined by Thermal Extraction Desorption Gas Chromatography/Mass Spectrometry. Using special microfilter crucibles allows the estimation of the particle sizes of the emitted MP, which is a fundamental requirement for an assessment of potential health hazards for humans.
Advances in ultrafast laser manufacturing: nanostructures, thin films, and scaling perspectives
(2024)
Advanced ultrafast laser technology is a rapidly growing field that currently enables many new industrial and scientific applications. During the last decades, this has been significantly driven by the availability of high-repetition-rate laser sources and novel beam delivery concepts. At the laser side, Moore’s law equally manifests for ultrafast laser technologies, since the average output power of such lasers doubles approximately every two years. This development is mainly driven by the increase of the pulse repetition rates of energetic laser pulses, currently enforcing the development of smart beam control and novel scanning strategies for preventing heat-accumulation and plasma-shielding effects during laser-based materials processing. This keynote presentation addresses the advantages, recent developments, and perspectives of laser processing with ultrashort laser pulses. A special focus is laid on the tailored structuring of thin films as well as the manufacturing and probing of sub-diffraction surface nanostructures – an ongoing race to extreme scales. Current limitations are identified and an outlook to future scaling perspectives will be provided.
AbstractMicroplastics (MP) can be detected in all environmental systems. Marine and terrestrial aquatic systems, especially the transported suspended solids, have often been the focus of scientific investigations in the past. Sediments of aquatic river systems, on the other hand, were often ignored due to the time‐consuming sample preparation and analysis procedures. Spectroscopic measurement methods counting particle numbers are hardly suitable as detection methods, because there are plenty of natural particles next to a small number of MP particles. Integral methods, such as thermoanalytical methods are determining the particle mass independently of the inorganic components.In this study, a workflow for sample preparation via density separation and subsequent analysis by thermal extraction desorption‐gas chromatography/mass spectrometry is presented, which leads to representative and homogeneous samples and allows fast and robust MP mass content measurements suitable for routine analysis. Polymers were identified and quantified in all samples. Polyethylene and styrene‐butadiene rubber are the dominant polymers, besides polypropylene and polystyrene. Overall, total polymer masses between 1.18 and 337.0 µg/g could be determined. Highest MP concentrations in riverbed sediment are found in sites characterized by low flow velocities in harbors and reservoirs, while MP concentrations in sandy/gravelly bed sediments with higher flow velocities are small.
By automatically recording as much information as possible in automated laboratory setups, reproducibility and traceability of experiments are vastly improved. This presentation shows what such an approach means for the quality of experiments in an X-ray scattering laboratory and an automated synthesis set-up.
Bakterielle Biofilme stellen in medizinischen und industriellen Bereichen ein ernsthaftes Problem dar. Eine der größten gesellschaftlichen Herausforderungen liegt in der zunehmenden Resistenz von Bakterien gegen Biozide, die bei antimikrobiellen Behandlungen eingesetzt werden, z.B. durch übermäßigen Einsatz in Medizin, Industrie und Landwirtschaft oder durch Reinigung und Desinfektion in Privathaushalten. Daher sind neue effiziente bakterienabweisende Strategien, die den Einsatz von Bioziden vermeiden, dringend erforderlich.
Ein vielversprechender Weg zur Erzielung bakterienabweisender Oberflächen liegt in der berührungslosen und aseptischen großflächigen Laserbearbeitung von technischen Oberflächen. Maßgeschneiderte Oberflächentexturen, ermöglicht durch verschiedene Laserbearbeitungsstrategien, die zu topographischen Skalen im Bereich von Nanometern bis Mikrometern führen, können eine Lösung für diese Herausforderung darstellen.
In dem Vortrag wird ein Überblick über den aktuellen Stand der Technik bei der subtraktiven Texturierung von Laseroberflächen zur Kontrolle der Biofilmbildung bei verschiedenen Bakterienstämmen und in unterschiedlichen Umgebungen gegeben. Auf der Grundlage spezifischer Eigenschaften von Bakterien und laserbearbeiteten Oberflächen werden die Herausforderungen antimikrobieller Oberflächendesigns erörtert und zukünftige Richtungen aufgezeigt.
Calcium sulfate hemihydrate (CaSO4ᐧ0.5H2O), also known as bassanite, has been used as a precursor to produce gypsum (dihydrate, CaSO4ᐧ2H2O) for various construction and decorative purposes since prehistoric times. The main route to obtain hemihydrate is a thermal treatment of gypsum at temperatures typically between 150 °C and 200 °C to remove some of the structural water.
In this contribution, we introduce (Fig. 1) a more efficient and sustainable method (T < 100 °C) that enables the direct, rapid, and reversibly conversion of gypsum to bassanite using reusable high salinity aqueous solutions (brines with c[NaCl] > 4 M). The optimum conditions for the efficientproduction of bassanite in a short time (< 5 min) involve the use of brines with c(NaCl) > 4 M and maintaining a temperature, T > 80 °C. When the solution containing bassanite crystals is cooled down to around room temperature, eventually gypsum is formed. When the temperature is raised again to T > 80 °C, bassanite is rapidly re-precipitated. This contrasts with the typical behaviour of the bassanite phase in low salt environments.
Traditionally, hemihydrate is obtained through a solid state thermal treatment because bassanite is considered to be metastable with respect to gypsum and anhydrite in aqueous solutions, and therefore gypsum-to-bassanite conversion should not occur in water. Its very occurrence actually contradicts numerical thermodynamic predictions regarding solubility of calcium sulfate phases. By following the evolution of crystalline phases with in situ and time-resolved X-ray diffraction/scattering and Raman spectroscopy, we demonstrated that the phase stability in brines at elevated temperatures is inaccurately represented in the thermodynamic databases. Most notably for c(NaCl) > 4 M, and T > 80 °C gypsum becomes readily more soluble than bassanite, which induces the direct precipitation of the latter from gypsum. The fact that these transformations are controlled by the solution provides extensive opportunities for precise manipulation of crystal formation. Our experiments confirmed that bassanite remained the sole crystalline structure for many hours before reverting into gypsum. This property is extremely advantageous for practical processing and efficient crystal extraction in industrial scenarios.
Inputs of plastic impurities into the environment via the application of fertilizers are regulated in Germany and the EU by means of ordinances. Robust and fast analytical methods are the basis of legal regulations. Currently, only macro- and large microplastic contents (>1 mm) are measured. Microplastics (1–1,000 µm), are not yet monitored. Thermal analytical methods are suitable for this purpose, which can determine the mass content and can also be operated fully automatically in routine mode. Thermal extraction desorption-gas chromatography/mass spectrometry (TED-GC/MS) allows the identification of polymers and the determination of mass contents in solid samples from natural environments. In accordance with the German or European Commission (EC) Fertiliser Ordinance, composting plants should be monitored for microplastic particles with this method in the future. In this context a compost plant was sampled. At the end of the rotting process, the compost was sieved and separated in a coarse (>1 mm) and a fine fraction (<1 mm). The fine fraction was processed using density separation comparing NaCl and NaI as possible salt alternative and screened for microplastic masses by TED-GC/MS with additional validation and quality assurance experiments. With TED-GC/MS total microplastics mass contents of 1.1–3.0 μg/mg in finished compost could be detected with polyethylene mainly. What differs much to the total mass of plastics in the coarse fraction with up to 60 μg/mg, which were visually searched, identified via ATR-FTIR and gravimetrically weighted.
Surfaces of metallic copper and copper alloys effectively inactivate microorganisms and viruses. However, the exact inactivation mode is still under debate. Main factors are assumed to include direct contact with the metallic surface, influx of Cu(I)/Cu(II) ions and the generation of reactive oxygen species (ROS). Laser-induced periodic surface structures (LIPSS) are frequently reported to act antibacterial, mainly by prevention of bacterial adhesion due to a limited number of possible adhesion points or by increasing the overall surface of intrinsically antibacterial materials. In time-kill experiments with E. coli and S. aureus we analyzed the impact of LIPSS on the toxicity of metallic copper and brass. We also conducted ROS accumulation assays and conclude that the application of LIPSS is not generally straight forward to obtain or improve antibacterial surfaces. Thus, the antibacterial effects of LIPPS.
Bacteria are ubiquitous and colonize all types of surfaces, including those in close proximity to humans, such as skin, food, and everyday objects. This raises the question of whether their presence represents a problem to be mitigated or a potential source of benefit to be harnessed, thereby stimulating scientific inquiry into the role of surface-associated bacteria in diverse domains ranging fromhuman health to industrial biotechnology. Aim: The objective of this project is to explore the impact of modifying surface topography on bacterial adhesion behavior. By manipulating the physical characteristics of the substrate, the attachment and detachment dynamics of bacteria can potentially be modified, leading to novel strategies for controlling bacterial colonization in various applications, such as medical devices. Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) were tested on LIPSS-covered Fused Silica samples.
Design and construction of a rainfall simulator to test metal runoff at atmospheric conditions
(2023)
A rainfall simulator was presented as an environmental assessment tool to quantify wash-off concentrations from metallic materials. It is part of the RUNOFF-project, which studies and re-assesses the durability of roofing and facade materials under current atmospheric conditions in Germany.
Studying building materials is important as they have a significant impact on achieving a variety of goals and targets within the sustainable developments goals (SDGs). The durability of materials is essential to reach sustainability. However, the durability of metallic materials is strongly depended on climate conditions, which have changed as a result of technical measures in industry, climate change and increasing urbanisation. In Germany at least, the data base is not up-to-date leading to prediction models regarding corrosion resistance and durability of metallic materials which can no longer be trusted and therefore need to be re-assessed and updated. Also, not only the demand for sustainable but also environmentally friendly building materials has increased dramatically. A number of construction materials produce chemical hazards, and therefore have negative impacts on water quality, soils health and ecosystems. To limit these impacts, environmental assessment methods and tools are needed to measure and quantify the inputs and outputs of building materials throughout their lifetime.
Im Verbundprojekt RUSEKU wurde die Probenahme von Wasserproben entscheidend weiterentwickelt. Wichtig ist hierbei zu gewährleisten, dass genügend Merkmalsträger in jeder Probe untersucht werden. Es muss daher eine für den Probenahmeort repräsentative Beprobung hinsichtlich des Wasservolumens in Abhängigkeit der Partikelanzahl gewährleistet sein.
Das Hauptaugenmerk lag im vorliegenden Projekt auf einer praxisnahen Beprobungsstrategie. Es wurden verschiedene Konzepte ausprobiert.
• Grundsätzlich hat sich gezeigt, dass eine Stichprobe eine Momentaufnahme des MP-Massengehaltes zeigt. Es wird eine hohe Statistik, also eine Vielzahl an Messungen am gleichen Probenahmeort, benötigt, um eine valide Aussage über den MP-Gehalt zu machen.
• Es zeigt sich, dass eine integrale Probenahme über mehrere Wochen mit dem SK routinemäßig möglich ist. Die erfassten MP-Massen sind reproduzierbar und robust.
• Die DFZ ist für Stichproben geeignet. Partikel < 50 µm werden eventuell unterschätzt
• Die fraktionierte Filtration kann für Stich- und Mischproben direkt im Feld genutzt werden. Fraktionen von 10 und 5 µm werden später im Labor Vakuum filtriert. Es erfolgt eine Fraktionierung der Probe mit Siebmaschenweiten von 1000, 500, 100, 50, 10 und 5 µm.
• Die fraktionierte Filtration kann auch anschließend an die Beprobung mit dem SK zur Anwendung kommen. Wird die mit dem SK gewonnene Wasserprobe fraktioniert filtriert, kann neben einem MP-Gesamtgehalt auch eine Einschätzung über die Partikelgrößen gewonnen werden.
• Für Wässer mit geringen Partikelzahlen wurde ein Messfiltertiegel entwickelt. Dieser hat eine Maschenweite von 6 µm. Seine Anwendung kann mögliche Verluste beim Transferieren vom Probenahmetool zum Messgefäß und mögliche Kontaminationen reduzieren.
Die Optimierung der Probenahmestrategie wurde durch Modellversuche und Simulationen unterstützt. Modellversuche zum Sinkverhalten und Simulationen von MP in realen Gewässern verdeutlichten das komplexe Verhalten der Partikel. Es konnte gezeigt werden, dass Partikel ab einer bestimmten Größe (und kleiner) bei genügend starker Turbulenz sich in der Wassersäule unabhängig von ihrer Dichte verhalten und so auch MP mit kleiner Dichte (z.B. PE) in der gesamten Wassersäule zu finden sind. Es konnte mit dem TEM die Existenz von NP gezeigt werden.
Ein wesentlicher Aspekt des RUSEKU Projektes war die Beprobung realer Kompartimente. Beprobt wurde neben Oberflächengewässern, das urbane Abwassersystem der Stadt Kaiserslautern, Waschmaschinenabwasser und Flaschenwasser.
• In Oberflächengewässern wurde hauptsächlich PE gefunden. Je nach Probe und Gewässer konnten auch PP, PS, PET, PA, SBR und Acrylate nachgewiesen werden.
• Im urbanen Abwassersystem der Stadt Kaiserslautern konnte an allen Probenahmestandorten MP nachgewiesen werden. Es wurde hauptsächlich PE, neben geringeren Mengen an PP, PS und SBR gefunden. Nach einem Regenereignis war der SBR Anteil deutlich erhöht.
• Die Beprobung eines realen Wäschepostens, bestehend aus T-Shirts und Hemden mit PA/CO oder PES/CO Mischgewebe, zeigte einen PA- und PES-Austrag im Waschwasser. Der überwiegende Teil der detektierten Fasern ist aber auf Baumwolle zurückzuführen. Reine gravimetrische Messungen zur Detektion von MP führen zu einer starken Überschätzung.
• In Flaschenwasser (PET-Flaschen) konnte MP detektiert werden. PET wurde nur im stillen Mineralwasser, nicht in Mineralwasser mit Kohlensäure gefunden werden. Teilweise wurde auch das MP-Material des Verschlusses im Wasser detektiert.
• Für Luftproben konnte ein Aufbau zur größenselektiven Beprobung getestet werden.
Neben der Probenahme hat das Projekt auch gezeigt, dass die TED-GC/MS geeignet für die MP-Detektion im Routinebetrieb ist. Die TED-GC/MS konnte weiter optimiert werden. Es wurden MP-Massen bestimmt.
Im Projekt wurden erste realitätsnahe Referenzmaterialien für die MP Detektion hergestellt. Die Herstellung von realitätsnahen Polymeren in ausreichender Homogenität und Menge hat sich als große Herausforderung herausgestellt.
A new concept for the ecotoxicological assessment of plastics under consideration of aging processes
(2023)
Microplastics are widely distributed in aquatic and terrestrial environments, but up to now less is known about (eco)toxicological impacts under realistic conditions. Research so far has focused mainly on impacts on organisms by fresh, single‐origin plastic fragments or beads. However, plastics found in the environment are complex in composition, this means different polymer types and sources, with and without additives and in all stages of age, and therefore, in a more or less advanced stage of degradation. For oxidized degradation products that might be released from plastic materials during aging, there is a lack of information on potentially adverse effects on aquatic biota. The latter is of particular interest as oxidized degradation products might become more water soluble due to higher polarity and are more bioavailable, therefore. The present study focused on plastic leachates of polystyrene (PS) and polylactic acid (PLA), which were derived from alternating stress by hydrolysis and ultraviolet (UV) radiation—representing a realistic scenario in the environment. Test specimens of PS, PLA, or a PLA/PS layer (each 50%) were alternately exposed to UV radiation for 5 days followed by hydrolysis for 2 days, for several weeks alternating. Ecotoxicological effects of the storage water (artificial freshwater) of the test specimens and additionally, in a second experimental setup, the effects of five potential polymer degradation products were detected by 72 h algae growth inhibition tests with Desmodesmus subspicatus. Results clearly indicate inhibitory effects on algae growth by contaminants in the storage water of stressed plastics with increasing growth inhibition of proceeding hydrolysis and UV stress times. Different polymers caused variable inhibitions of algae growth with stronger inhibitions by PS and less effects by PLA and the mixed layer of both. Moreover, not microplastic particles but the resulting dissolved degradation products after aging caused the ecotoxicological effects—with strong effects by the oxidized degradation products. The existing data highlight the relevance of plastic aging as a framework for microplastic ecotoxicity evaluation and allow a proof of concept.