Microplastics in ecosystems: from current trends to bio-based removal strategies

Plastics are widely used due to their excellent properties, inexpensiveness and versatility leading to an exponential consumption growth during the last decades. However, most plastic does not biodegrade in any meaningful sense; it can exist for hundreds of years. Only a small percentage of plastic waste is recycled, the rest being dumped in landfills, incinerated or simply not collected. Waste-water treatment plants can only minimize the problem by trapping plastic particles of larger size and some smaller ones remain within oxidation ponds or sewage sludge, but a large amount of microplastics still contaminate water streams and marine systems. Thus, it is clear that in order to tackle this potential ecological disaster, new strategies are necessary. This review aims at briefly introducing the microplastics threat and critically discusses emerging technologies, which are capable to efficiently clean aqueous media. Special focus is given to novel greener approaches based on lignocellulose flocculants and other biomaterials. In the final part of the present review, it was given a proof of concept, using a bioflocculant to remove micronized plastic from aqueous medium. The obtained results demonstrate the huge potential of these biopolymers to clean waters from the microplastics threat, using flocculants with appropriate structure.UIDB00102/2020/ UIDB/05183/2020/ PTDC/AGR-TEC/4814/2014/ PTDC/ASP-SIL/30619/2017/ CEECIND/01014/2018info:eu-repo/semantics/publishedVersio

Improved Aerosol Deposition Profiles from Dry Powder Inhalers

Lung diseases such as asthma and chronic obstructive pulmonary disease (COPD) are major health burdens on the global population. To treat diseases of the lung, topical therapies using dry powder inhalers (DPIs) have been employed. However, a relatively small amount of dose (5.5 – 28 %) reaches the lung during DPI therapy leading to high inter-patient variability in therapy response and oropharyngeal deposition. Strategies were assessed to take patient variability in inhalation performance into account when developing devices to reduce throat deposition and to mitigate flow rate dependency of the emitted aerosol. A cyclone-spacer was manufactured and evaluated with marketed and in-house manufactured formulations. An in vivo study showed that a high resistance inhaler would produce longer inhalation times in lung disease patients and that a spacer with high resistance may prove a suitable approach to address inter-patient variability. Two spacer prototypes were evaluated with cohesively- and adhesively-balanced particle blends. The data suggested that the throat deposition dramatically decreased for the emitted particles when the spacers were used with the inhalers (e.g. 18.44 ± 2.79% for salbutamol sulphate, SS 4 kPa) due to high retention of the formulation within the spacer (87.61 ± 2.96%). Moreover, variation in fine particle fraction and dose was mitigated when increasing the flow rate (82.75 ± 7.34 %, 92.2 ± 7.7 % % and 77.0 ± 10.1 % at 30, 45 and 60 Lmin-1, respectively). The latter was an improvement over previous proposed DPI spacers, where variability in emitted dose due to airflow rate was a major issue. Due to the different physicochemical properties of the active pharmaceutical ingredients used in the formulation, throat deposition and respirable fraction for adhesively-balanced particles (e.g. SS) were double that of the cohesively- balanced particles (salmeterol xinafoate, SX) (e.g. 65.83 ± 8.99 % vs. 45.83 ± 5.04 % for SS:Coarse Lactose (CL) and SX:CL, respectively). Scanning electron microscopy revealed that surface-bound agglomerates were more freely removed from the carrier, but subject to decreased impaction-type deagglomeration forces in the spacer than for carrier-bound drug. An ex vivo study using breath profiles from healthy volunteers identified the minimization of differences between adhesively- and cohesively-balanced blends when full breath profiles were studied compared to square-wave airflow. Therefore the use of constant flow for in vitro testing should not be the sole flow regime to study aerosolization when developing new inhalation devices and formulations

Electrospun Recycled Polyethylene Terephthalate Microfibers as an Asphalt Mix Additive

In recent decades, the use of different types of fibers in asphalt has become increasingly popular. Fibers are used in an asphalt mix to improve its durability and resistance against distresses such as rutting and cracking due to repetitive vehicle loading at high temperatures, and low-temperature contraction. Consequently, accurate rheological and performance characterization of asphalt binders and mixes containing fibers is of vital importance. With increased concerns over the environmental disruptions as a result of disposing end-of-life plastics in landfills and the need for improving sustainability of the construction materials, incorporating plastic in construction materials has always been an important topic for researchers. Among different types of plastics, containers made from polyethylene terephthalate (PET) constitute a large portion of the waste plastic problem. While using waste PET particles in asphalt mixes has been found to be a feasible option, mechanical properties of final product may not adequately benefit from the high modulus and tensile strength of PET plastic. In this study the end-of-life PET plastic obtained from bottled water containers was used for production of PET microfibers using a fiber production technique known as electrospinning. A solution-based electrospinning method was employed in the laboratory to produce electrospun PET microfibers (EPM) by using different concentrations of PET in the solution and discharge rates. Then, the effect of using EPM as an additive on asphalt mix properties was investigated. The selection of PET as the feedstock for EPM production was made due to its high thermal stability, ductility, surface area, and strain resistance. EPM was produced from a solution of micronized PET (MPET) in a mix of dichloromethane (DCM) and trifluoroacetic acid (TFA). Two MPET concentrations, namely 15 and 20% and various solution discharge rates, namely 40, 50, 60, 120, and 250 μL/min were utilized to determine the effects of the electrospinning parameters on the mechanical and chemical characteristics of the produced EPM. For this purpose, Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), and tensile strength tests were conducted on produced EPMs. To evaluate the feasibility of incorporating EPM in the asphalt mixes, a comprehensive testing program was carried out in this study. The performance of asphalt mixes containing different amounts of EPM was assessed by conducting Hamburg wheel tracking (HWT), semi-circular bend (SCB), and tensile strength ratio (TSR) tests. These tests were included in the experimental design to determine the resistance of the asphalt mixes to rutting, cracking, and moisture-induced damage. FTIR spectroscopy analysis revealed that the electrospinning parameters and solution’s proportions did not alter the molecular structure of the PET or generate new molecules. Analyzing the SEM micrographs showed that the diameter distribution in the EPM fibers decreased with a reduction in discharge rates at a constant MPET concentrations. In addition, morphological examination of SEM micrographs suggested that the most uniform and smooth fibers were consistently produced at the lowest discharge rate. Increasing the discharge rates resulted in the formation of fibers with rough textures, non-uniform in shape and size, and fractured. The mechanical properties of the produced EPM also exhibited a correlation with the fibers’ diameters. More specifically, fibers having smaller diameter resulted in enhanced mechanical properties. In view of the findings pertinent to the EPM’s chemical composition, morphological characteristics, mechanical properties, and yield consideration electrospinning using a solution of 20% MPET concentration and a discharge rate of 60 μL/min was found to result in EPMs of optimal mechanical and morphological properties. Performance tests conducted on asphalt mixes revealed that the addition of EPM to asphalt mixes improved their resistance to rutting, based on the HWT test. Asphalt mixes containing 0.5 and 1.0% EPM by binder weight tested in a HWT device exhibited a resistance to rutting and moisture-induced damage which were greater than those of the mixes which did not contain any EPM. However, increasing the EPM content to 1.5% by the weight of binder was not found to benefit its resistance to rutting. Conducting TSR tests on asphalt mixes revealed that incorporating EPM in the mixes enhanced their resistance to moisture-induced damage, confirming the findings of the HWT tests. Finally, conducting SCB tests revealed that incorporating EPM in asphalt mixes resulted in an improved resistance to cracking when compared to mixes which did not contain any EPM. Overall, it was concluded that incorporating EPM in asphalt mixes can potentially be a feasible approach to reduce plastic landfills and improve the performance and sustainability of the ground transportation system

Triboelektrische Trennung - Eine neue Methode zur Trennung feiner organischer Pulver?

Triboelectric separation is a technique to separate dry powders according to their ability to generate charge. Charge generation occurs due to the contact of and subsequent separation of two surfaces. A physical description of the triboelectric effect is still unknown. For particles flowing through a tube, particle-particle and particle-wall interaction occur. To enhance separation properties of binary powder mixtures charge generation are enlarged by increasing particle-particle interactions, whereas materials of the tube wall do not influence the separation properties.Die triboelektrische Trennung ist eine Methode, um trockene Pulver durch ihre Ladungserzeugung zu trennen. Die Ladungserzeugung erfolgt durch Kontakt und anschließende Trennung zweier Oberflächen. Eine physikalische Beschreibung des triboelektrischen Effekts ist noch nicht bekannt. Bei Partikeln, die durch ein Rohr strömen, treten Partikel-Partikel und Partikel-Wand Kontakte auf. Ein Erhöhen der Partikel-Partikel Kontakte führt zu erhöten Trenneigenschaften, wohingegen die Materien der Rohrwand diese nicht beeinflussen

Valorizing and Remediating Synthetic Polymers with Tenacious Backbones

Synthetic polymers or plastics are manufactured long-chained molecules primarily sourced from nonrenewable fossil fuels like petroleum. Owing to their superior properties (e.g., durability, impermeability, and high strength to mass ratio), plastics are the most widely used material, replacing traditional materials like metals, wood, and glass. However, the same properties that make plastics desirable are also responsible for their recycling difficulty and biopersistence. As a result, over 79% of the 6.3 billion metric tons of plastics waste generated to date accumulates in landfills or escapes into the environment, persisting for decades or centuries. This thesis highlights the immensity of plastics pollution and contributes polymer chemistry-based solutions in recycling and remediation methodologies. Chapter 1 emphasizes that the desirable properties of plastics are also responsible for their problematic persistence in the environment, causing a predicament where plastics are indispensable yet detrimental to the environment. Because it is impractical for society to avoid plastics altogether, developing recycling and remediation methods that use waste plastics as feedstocks alleviates their environmental impact. Many polymers, however, cannot be recycled via mechanical processes, and as a result, they are incinerated or landfilled. These waste plastics slowly disintegrate into microplastics, which are significant environmental pollutants and have problematic health effects. One example is the superabsorbent material made of crosslinked sodium polyacrylate used in diapers and feminine hygiene products. We aimed to develop a chemical recycling solution for the superabsorbent polymer used in Procter and Gamble’s (P&G’s) hygiene products (PAAP&G). After discussing various chemical recycling methods, we highlight the unavailability of closed-loop recycling methods for PAAP&G. We then transition to chapter 2, where we present an open-loop recycling method inspired by the common acrylic acid origin of PAAP&G and pressure-sensitive adhesives. This transformation was executed in three steps, namely (i) decrosslinking via hydrolysis, (ii) an optional chain-shortening step via sonication, and (iii) functionalizing via base-mediated esterification. Viscoelastic properties were tuned by adjusting the molar mass using sonication or incorporating amine functional groups, making adhesives spanning various applications, including tapes, bandages, and sticky notes. Any new recycling methodology requires an unbiased comparative evaluation to determine its processing and environmental impacts—chapter 3 utilized life cycle assessment to evaluate and improve the recycling method presented in chapter 2. The significant improvements to the previously developed process include: (i) replacing the base hydrolysis with acid hydrolysis and (ii) replacing the base-mediated esterification with Fischer esterification. Life cycle assessment suggested that our new approach outperforms the conventional petroleum-based route on nearly every metric, including carbon dioxide emissions and energy usage. Recycling diapers and feminine hygiene products through this method could avoid the disposal of 2 million metric tons of polymer waste annually. Chapter 4 begins with accidentally discovering that the adhesives developed in chapters 2 and 3 effectively captured micronized rubber, a type of microplastics, in a mixed solvent waste container. Next, we demonstrated the removal of various microplastics using adhesive-coated glass slides followed by quantitatively evaluating removal in suspensions of 10 μm polystyrene as a function of adhesive molar mass. We successfully quantified polystyrene removal using flow cytometry without fluorescent labeling and confirmed > 99% removal efficiencies. Chapter 5 summarizes each chapter and recommends future directions, including preliminary work towards developing a one-pot process to recycle PAAP&G to make PSAs where the idea stems from the similarity between acid hydrolysis and acid-catalyzed esterification.PHDChemistryUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/170029/1/paulchaz_1.pd

END OF LIFE MANAGEMENT OF ELECTRONIC WASTE

Electronic products are becoming obsolete at a very high rate due to rapid changes in consumer demand and technological advancements. However, on other hand End-of-Life (EOL) management of electronic products is not effectively approached while these products offer huge opportunities for effective recycling. In this context, this thesis has highlighted the current practices and issues related to EOL management of electronic products focusing on their different material compositions, the uses of their raw materials in the circular economy perspective. The thesis proposes the introduction of digital technologies into the recycling process to improve efficiency. More specifically, this thesis has focused on the corona electrostatic separation process and the improvement of efficiency based on the simulation of the particle trajectories to identify the most effective parameters. Thus, in this frame, a numerical model to predict the particle trajectories in a corona electrostatic separator is developed using COMSOL Multiphysics and MATLAB software and validated with experimental trials. The recycling of electronic waste is becoming challenging due to its diverse and constantly changing material composition. In this regard, this thesis illustrates the use of non-destructive visible near-infrared hyperspectral imaging (VNIR-HSI) technique to identify material accurately; the effectiveness of VNIR-HSI is demonstrated through an experimental campaign combined with machine learning models, such as Support Vector Machine, K-Nearest Neighbors and Neural Network.Nonostante i prodotti elettronici diventino obsoleti ad un ritmo molto elevato, a causa dei rapidi cambiamenti nella domanda dei consumatori e dei progressi tecnologici, la gestione del loro fine vita (End-of-Life (EOL)) non viene affrontata in modo efficace benché offra, invece, grandi opportunità di riciclo. In questo contesto, questa tesi ha evidenziato le attuali pratiche e problematiche relative alla gestione del fine vita dei prodotti elettronici concentrandosi sulla loro diversa composizione, l’utilizzo delle materie prime seconde ricavabili in una prospettiva di economia circolare. La tesi propone l’introduzione di tecnologie digitali nel processo di riciclo per migliorarne l'efficienza. In particolare, questa tesi si è concentrata sul processo di separazione elettrostatica a corona e sul miglioramento dell'efficienza grazie alla simulazione delle traiettorie delle particelle per identificare i parametri più efficaci. Pertanto, in questo studio, utilizzando i software COMSOL Multiphysics e MATLAB, è stato sviluppato un modello numerico per prevedere le traiettorie delle particelle in un separatore elettrostatico a corona; il modello è stato poi validato con prove sperimentali. Il riciclo dei rifiuti elettronici sta diventando sempre più complesso a causa della presenza di mix di materiali diversificati e in continua evoluzione. A questo proposito, la tecnologia di visione iperspettrale non distruttiva basata su lunghezze d’onda nel visibile e nel vicino infrarosso (VNIR-HSI) è stata utilizzata in questo lavoro di tesi per identificare il materiale in modo preciso; l'efficacia di VNIR-HSI, combinato con modelli di apprendimento automatico, come la Support Vector Machine, K-Nearest Neighbors e Neural Network, viene dimostrata attraverso una campagna sperimentale

Electroencapsulation and electrospraying of pharmaceutical materials in preparation for oral drug delivery applications

In bi-polar parallel nozzle electroencapsulation, two oppositely charged droplet jets are produced by electrospraying (electrostatic atomization), a method of extracting micro- or nanodroplets from a body of liquid using electrical forces. The two species of droplets are attracted to each other due to Coulombic forces. Upon contact, droplets of similar size can merge into a single-phase, or form a core-shell capsule structure, depending on the mutual miscibility of the liquids. In this work, an electroencapsulation setup was designed and experimented for the single-step production of two types of drug carrier particles of 10–50 μm in size: wrinkled, solid Eudragit L 100 enteric polymer micromatrix particles; and spherical microcapsules consisting of a solid Eudragit E 100 polymer shell and a liquid glycerol core. The carrier particle payload consisted of a model drug (griseofulvin); or griseofulvin loaded, mesoporous silicon (PSi) nano- and microparticles, which themselves are functional drug carriers. The goal was to obtain the carrier particle payloads as either stable drug dispersions in a disordered solid state, or non-agglomerated PSi nanoparticle dispersions, to enhance the drug dissolution properties at release. The carrier formulations would effectively render the payload in the form of an inert micropowder for purposes of handling and dosing. In oral administration, the formulations were to shield the payload from intestinal metabolism, and to restrain its release until arrival to target pH-conditions. The carrier particles were characterized to evaluate these properties. The micromatrix particles were proven stable and gastro-resistant in vitro. Griseofulvin dissolution and absorption properties improved significantly, the latter especially for the drug loaded PSi payloads. Finally, the efficiency of the asymmetric core-shell microcapsule production was optimized using Taguchi techniques. In conclusion, electroencapsulation was found to be a potentially feasible method to improve the oral bioavailability of poorly soluble drugs. Furthermore, partially crystalline piroxicam microparticles were produced by electrospraying, and characterized. The crystalline phase was shown to consist of a previously unknown, stable polymorphic form of piroxicam. The result suggests the method could provide a unique way to produce novel drug polymorphs. Thus, it is possible that the dissolution properties of certain drug materials could be improved sufficiently to facilitate oral administration, without the necessity to use more complex formulations