49 research outputs found

    A thermoanalytical insight into the composition of biodegradable polymers and commercial products by EGA-MS and Py-GC-MS

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    Biodegradable polymers are proposed as a potential solution to environmental problems related to plastic pollution. Potential benefits have been suggested in applications such as agricultural mulching and fishing gear, where there can be considerable difficulty recovering products from the environment at the end of their service life. Biodegradation is a complex process influenced by both the properties of the material and the receiving environment in which it needs to biodegrade. Assessing the degradation process necessitates the chemical composition (i.e. polymer and additives) of biodegradable products to be characterised by reliable analytical methods. Pyrolysis coupled to Gas Chromatography and Mass Spectrometry (Py-GC-MS) and Evolved Gas Analysis coupled to Mass Spectrometry (EGA-MS) are emerging techniques to characterise plastic materials, providing a greater sensitivity and resolution when compared to more widely used spectroscopic techniques (FTIR and Raman). In this work, we have applied a systematic approach combining EGA-MS and multi-shot Py-GC-MS for the thermoanalytical investigation of 5 biodegradable polymers and 5 biodegradable-labelled commercial products. We identified thermal degradation profiles, main m/z ions and pyrolysis markers for the polymers PBAT, PBS, PBHV and two types of PLA. We applied the obtained information to investigate the composition of 4 mulch films and 1 fishing net. EGA-MS was fundamental to optimise single or multi shot pyrolysis acquisition, allowing an optimal Py-GC-MS separation and identification of the pyrolysis products. PLA and PBAT were detected in three mulch films, with the addition of starch in a film labelled as Mater-Bi and in one of unknown composition. Online silylation was crucial for detecting polysaccharides in a composite film containing hemp fibres. The presence of butylene, succinate, adipate and terephthalate units was highlighted analysing a fishing net made of a newly developed PBSAT resin. Finally, Py-GC-MS was effective in identifying the presence of additives such as 1,6-diisocyanato-hexane (chain extender) and di(3-butenyl) ester of sebacic acid derived from the plasticizer dibutyl sebacate

    Tunable Ag@SiO2 core-shell nanocomposites for broad spectrum antibacterial applications

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    Silica encapsulated silver nanoparticle core–shell nanocomposites of tunable dimensions were synthesised via a one-pot reverse microemulsion route to achieve controlled release of Ag+ ions for broad spectrum antibacterial application. Silver release rates and bactericidal efficacy against Gram-positive and Gram-negative bacteria, S. aureus and P. aeruginosa respectively, were inversely proportional to nanoparticle core diameter (3–8 nm) and silica shell (7–14 nm) thickness, and readily tuned through a facile hydrothermal etching protocol employing a PVP stabiliser to introduce mesoporosity

    Deep dive into the chronic toxicity of tyre particle mixtures and their leachates.

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    This is the final version. Available from Elsevier via the DOI in this record. Data Availability: Data will be made available on request.Particles from the tread of vehicle tyres are a global pollutant, which are emitted into the environment at an approximate rate of 1.4 kg.year-1 for an average passenger-car. In this study, popular tyre brands were used to generate a tyre tread microparticle mixture. The chronic toxicity of both particles and chemical leachates were compared on a planktonic test species (Daphnia magna). Over 21 days of exposure, pristine tyre tread microparticles were more toxic (LC50 60 mg.L-1) than chemical lechates alone (LC50 542 mg.L-1). Microparticles and leachates showed distinct effects on reproduction and morphological development at environmentally relevant concentrations, with dose-dependent uptake of particles visible in the digestive tract. Chemical characterization of leachates revealed a metal predominance of zinc, titanium, and strontium. Of the numerous organic chemicals present, at least 54 were shared across all 5 tyre brands, with many classified to be very toxic. Our results provide a critically needed information on the toxicity of tyre tread particles and the associated chemicals that leach from them to inform future mitigation measures. We conclude that tyre particles are hazardous pollutants of particular concern that are close to or possibly above chronic environmental safety limits in some locations.Natural Environment Research Council (NERC

    Tailored mesoporous silica supports for Ni catalysed hydrogen production from ethanol steam reforming

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    Mesoporous silica supported Ni nanoparticles have been investigated for hydrogen production from ethanol steam reforming. Ethanol reforming is structure-sensitive over Ni, and also dependent on support mesostructure; three-dimensional KIT-6 possessing interconnected mesopores offers superior metal dispersion, steam reforming activity, and on-stream stability against deactivation compared with a two-dimensional SBA-15 support

    Cloud Computing As a Tool for Enhancing Ecological Goals?

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    Cloud computing has been introduced as a promising information technology (IT) that embodies not only economic advantages in terms of increased efficiency but also ecological gains through saving energy. The latter has become particularly important in view of the rising energy costs of IT. The present study analyzes whether necessary preconditions for accepting cloud computing as a new infrastructure, such as awareness and perceived net value, exist on the part of the users. The analysis is based on a combined research framework of the theory of reasoned action (TRA) and the technology acceptance model (TAM) in a cloud computing setting. Two consumer surveys, the one to elicit beliefs and the second to gain insight into the ranking of the variables, are employed. This study uses structural equation modeling (SEM) to evaluate the hypotheses. The results indicate support for the proposed research framework. Surprisingly however, the ecological factor does not play a role in forming cloud computing intentions, regardless of prior knowledge or experience. Empirical evidence of this study suggests increasing efforts for informing actual and potential users, particularly in respect to possible ecological advantages through applying the new IT infrastructure

    user centered design approaches and methods for p5 ehealth

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    As seen throughout this book, eHealth informed by P5 approach gives full recognition to patients' contexts, needs, desires, and personal characteristics. These aspects should not only be considered as cornerstones for technology evaluation, but as fundamental guidelines for design in the first place. This relates to User-Centered Design, that is, any technology/service design where final users influence how the design itself takes place. In other words, eHealth development should be based on research data gathered among final users about their needs and contexts of use, in order to be specifically tailored on final users even before the realization of low-level prototypes. This methodological contribution presents a critical presentation, description, and evaluation of research tools to be employed not to evaluate technology's results and effectiveness, but the specific characteristics of users in order to orient design and development. Such an approach should be considered the "gold standard" of P5 eHealth solutions

    Structure-Reactivity Relations in Ruthenium Catalysed Furfural Hydrogenation

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    Furfural is an abundant and low-cost bio-derived platform chemical, obtained by xylose dehydration, and an important precursor to furfuryl alcohol and furan resins. The liquid phase selective hydrogenation of furfural to furfuryl alcohol was systematically investigated over silica supported Ru nanoparticles to elucidate structure-reactivity relations and obtain mechanistic insight. Furfural hydrogenation to furfuryl alcohol is weakly structure sensitive for Ru nanoparticles spanning 2 to 25 nm, and the dominant reaction pathway reaching 95 % selectivity under our conditions (<25 bar H2 and 100165 °C). In contrast, furfural decarbonylation to furan exhibits a strong structure sensitivity, being favoured over sub-10 nm particles. Increasing pH2 from 10 to 25 bar resulted in a modest increase in C=O hydrogenation, while higher temperatures promoted ring-opening of furfuryl alcohol

    Platinum catalysed aerobic selective oxidation of cinnamaldehyde to cinnamic acid

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    Aerobic selective oxidation of allylic aldehydes offers an atom and energy efficient route to unsaturated carboxylic acids, however suitable heterogeneous catalysts offering high selectivity and productivity have to date proved elusive. Herein, we demonstrate the direct aerobic oxidation of cinnamaldehyde to cinnamic acid employing silica supported Pt nanoparticles under base-free, batch and continuous flow operation. Surface and bulk characterisation of four families of related Pt/silica catalysts by XRD, XPS, HRTEM, CO chemisorption and N2 porosimetry evidence surface PtO2 as the common active site for cinnamaldehyde oxidation, with a common turnover frequency of 49,000 ± 600 h-1; competing cinnamaldehyde hydrogenolysis is favoured over metallic Pt. High area mesoporous (SBA-15 or KIT-6) and macroporous-mesoporous SBA-15 silicas confer significant rate and cinnamic acid yield enhancements versus low area fumed silica, due to superior platinum dispersion. High oxygen partial pressures and continuous flow operation stabilise PtO2 active sites against in-situ reduction and concomitant deactivation, further enhancing cinnamic acid productivity
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