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1.
Nature ; 580(7802): 216-219, 2020 04.
Artigo em Inglês | MEDLINE | ID: mdl-32269349

RESUMO

Present estimates suggest that of the 359 million tons of plastics produced annually worldwide1, 150-200 million tons accumulate in landfill or in the natural environment2. Poly(ethylene terephthalate) (PET) is the most abundant polyester plastic, with almost 70 million tons manufactured annually worldwide for use in textiles and packaging3. The main recycling process for PET, via thermomechanical means, results in a loss of mechanical properties4. Consequently, de novo synthesis is preferred and PET waste continues to accumulate. With a high ratio of aromatic terephthalate units-which reduce chain mobility-PET is a polyester that is extremely difficult to hydrolyse5. Several PET hydrolase enzymes have been reported, but show limited productivity6,7. Here we describe an improved PET hydrolase that ultimately achieves, over 10 hours, a minimum of 90 per cent PET depolymerization into monomers, with a productivity of 16.7 grams of terephthalate per litre per hour (200 grams per kilogram of PET suspension, with an enzyme concentration of 3 milligrams per gram of PET). This highly efficient, optimized enzyme outperforms all PET hydrolases reported so far, including an enzyme8,9 from the bacterium Ideonella sakaiensis strain 201-F6 (even assisted by a secondary enzyme10) and related improved variants11-14 that have attracted recent interest. We also show that biologically recycled PET exhibiting the same properties as petrochemical PET can be produced from enzymatically depolymerized PET waste, before being processed into bottles, thereby contributing towards the concept of a circular PET economy.


Assuntos
Hidrolases/química , Hidrolases/metabolismo , Plásticos/química , Plásticos/metabolismo , Polietilenotereftalatos/química , Polietilenotereftalatos/metabolismo , Engenharia de Proteínas , Reciclagem , Actinobacteria/enzimologia , Burkholderiales/enzimologia , Hidrolases de Éster Carboxílico/química , Hidrolases de Éster Carboxílico/metabolismo , Dissulfetos/química , Dissulfetos/metabolismo , Ensaios Enzimáticos , Estabilidade Enzimática , Fusarium/enzimologia , Modelos Moleculares , Ácidos Ftálicos/metabolismo , Polimerização , Thermobifida
2.
Proc Natl Acad Sci U S A ; 120(23): e2220021120, 2023 06 06.
Artigo em Inglês | MEDLINE | ID: mdl-37252959

RESUMO

The consistent rise of plastic pollution has stimulated interest in the development of biodegradable plastics. However, the study of polymer biodegradation has historically been limited to a small number of polymers due to costly and slow standard methods for measuring degradation, slowing new material innovation. High-throughput polymer synthesis and a high-throughput polymer biodegradation method are developed and applied to generate a biodegradation dataset for 642 chemically distinct polyesters and polycarbonates. The biodegradation assay was based on the clear-zone technique, using automation to optically observe the degradation of suspended polymer particles under the action of a single Pseudomonas lemoignei bacterial colony. Biodegradability was found to depend strongly on aliphatic repeat unit length, with chains less than 15 carbons and short side chains improving biodegradability. Aromatic backbone groups were generally detrimental to biodegradability; however, ortho- and para-substituted benzene rings in the backbone were more likely to be degradable than metasubstituted rings. Additionally, backbone ether groups improved biodegradability. While other heteroatoms did not show a clear improvement in biodegradability, they did demonstrate increases in biodegradation rates. Machine learning (ML) models were leveraged to predict biodegradability on this large dataset with accuracies over 82% using only chemical structure descriptors.


Assuntos
Plásticos Biodegradáveis , Poliésteres , Poliésteres/química , Plásticos/química , Polímeros , Biodegradação Ambiental , Projetos de Pesquisa
3.
Proc Natl Acad Sci U S A ; 119(13): e2121426119, 2022 03 29.
Artigo em Inglês | MEDLINE | ID: mdl-35312352

RESUMO

SignificanceMore than 400 million tons of plastic waste is produced each year, the overwhelming majority of which ends up in landfills. Bioconversion strategies aimed at plastics have emerged as important components of enabling a circular economy for synthetic plastics, especially those that exhibit chemically similar linkages to those found in nature, such as polyesters. The enzyme system described in this work is essential for mineralization of the xenobiotic components of poly(ethylene terephthalate) (PET) in the biosphere. Our description of its structure and substrate preferences lays the groundwork for in vivo or ex vivo engineering of this system for PET upcycling.


Assuntos
Dioxigenases , Ácidos Ftálicos , Plásticos/química , Polietilenotereftalatos/química
4.
Anal Chem ; 96(26): 10662-10668, 2024 07 02.
Artigo em Inglês | MEDLINE | ID: mdl-38875183

RESUMO

The uptake of plastic particles by plants and their transport through the food chain make great risks to biota and human health. Therefore, it is important to trace plastic particles in the plant. Traditional fluorescence imaging in plants usually suffers significant autofluorescence background. Here, we report a persistent luminescence nanoplatform for autofluorescence-free imaging and quantitation of submicrometer plastic particles in plant. The nanoplatform was fabricated by doping persistent luminescence nanoparticles (PLNPs) onto polystyrene (PS) nanoparticles. Cr3+-doped zinc gallate PLNP was employed as the dopant for autofluorescence-free imaging due to its persistent luminescence nature. In addition, the Ga element in PLNP was used as a proxy to quantify the PS in the plant by inductively coupled plasma mass spectrometry (ICP-MS). Thus, the developed nanoplatform allows not only dual-mode autofluorescence-free imaging (persistent luminescence and laser-ablation ICP-MS) but also ICP-MS quantitation for tracking PS in plant. Application of this nanoplatform in a typical plant model Arabidopsis thaliana revealed that PS mainly distributed in the root (>99.45%) and translocated very limited (<0.55%) to the shoot. The developed nanoplatform has great potential for quantitative tracing of submicrometer plastic particles to investigate the environmental process and impact of plastic particles.


Assuntos
Arabidopsis , Nanopartículas , Arabidopsis/química , Nanopartículas/química , Luminescência , Plásticos/química , Tamanho da Partícula , Poliestirenos/química , Imagem Óptica
5.
Anal Chem ; 96(35): 14142-14149, 2024 Sep 03.
Artigo em Inglês | MEDLINE | ID: mdl-39172628

RESUMO

Cyclic olefin copolymers (COC; e.g., Zeonor, Topas, Arton, etc.) are materials with outstanding properties for developing point-of-care systems; however, the lack of functional groups in their native form makes their application challenging. This work evaluates different strategies to functionalize commercially available Zeonor substrates, including oxygen plasma treatment, photochemical grafting, and direct surface amination using an amino dextran-lipase conjugate (ADLC). The modified surfaces were characterized by contact angle measurements, Fourier transform infrared-attenuated total reflection analysis, and fluorescence assays based on evanescent wave excitation. The bioaffinity activation through the ADLC approach results in a fast, simple, and reproducible approach that can be used further to conjugate carboxylated small molecules (e.g., haptens). The usefulness of this approach has been demonstrated by the development of a heterogeneous fluorescence immunoassay to detect tacrolimus (FK506) immunosuppressant drug using an array biosensor platform based on evanescence wave laser excitation and Zeonor-ADLC substrates. Surface modification with ADLC-bearing FK506 provides a 3D layer that efficiently leads to a remarkably low limit of detection (0.02 ng/mL) and IC50 (0.9 ng/mL) together with a wide dynamic range (0.07-11.3 ng/mL).


Assuntos
Imunossupressores , Tacrolimo , Tacrolimo/química , Imunossupressores/química , Imunoensaio/métodos , Técnicas Biossensoriais/métodos , Plásticos/química , Humanos
6.
Crit Rev Biotechnol ; 44(3): 477-494, 2024 May.
Artigo em Inglês | MEDLINE | ID: mdl-36788704

RESUMO

Plastic biodegradation has emerged as a sustainable approach and green alternative in handling the ever-increasing accumulation of plastic wastes in the environment. The complete biodegradation of polyethylene terephthalate is one of the most recent breakthroughs in the field of plastic biodegradation. Despite the success, the effective and complete biodegradation of a wide variety of plastics is still far from the practical implementation, and an on-going effort has been mainly devoted to the exploration of novel microorganisms and enzymes for plastic biodegradation. However, alternative strategies which enhance the existing biodegradation process should not be neglected in the continuous advancement of this field. Thus, this review highlights various strategies which have shown to improve the biodegradation of plastics, which include the pretreatment of plastics using UV irradiation, thermal, or chemical treatments to increase the susceptibility of plastics toward microbial action. Alternative pretreatment strategies are also suggested and compared with the existing techniques. Besides, the effects of additives such as pro-oxidants, natural polymers, and surfactants on plastic biodegradation are discussed. In addition, considerations governing the biodegradation performance, such as the formulation of biodegradation medium, cell-free biocatalysis, and physico-chemical properties of plastics, are addressed. Lastly, the challenges and future prospects for the advancement of plastic biodegradation are also highlighted.


Assuntos
Plásticos , Polímeros , Plásticos/química , Plásticos/metabolismo , Polímeros/metabolismo , Biodegradação Ambiental , Biocatálise
7.
Anal Biochem ; 685: 115390, 2024 01 15.
Artigo em Inglês | MEDLINE | ID: mdl-37951454

RESUMO

To alleviate environmental problems caused by using conventional plastics, bioplastics have garnered significant interest as alternatives to petroleum-based plastics. Despite possessing better degradability traits compared to traditional plastics, the degradation of bioplastics still demands a longer duration than initially anticipated. This necessitates the utilization of degradation strains or enzymes to enhance degradation efficiency, ensuring timely degradation. In this study, a novel screening method to identify bioplastic degraders faster was suggested to circumvent the time-consuming and laborious characteristics of solid-based plate assays. This liquid-based colorimetric method confirmed the extracellular esterase activity with p-nitrophenyl esters. It eliminated the needs to prepare plastic emulsion plates at the initial screening system, shortening the time for the overall screening process and providing more quantitative data. p-nitrophenyl hexanoate (C6) was considered the best substrate among the various p-nitrophenyl esters as substrates. The screening was performed in liquid-based 96-well plates, resulting in the discovery of a novel strain, Bacillus sp. SH09, with a similarity of 97.4% with Bacillus licheniformis. Furthermore, clear zone assays, degradation investigations, scanning electron microscopy, and gel permeation chromatography were conducted to characterize the biodegradation capabilities of the new strain, the liquid-based approach offered a swift and less labor-intensive option during the initial stages.


Assuntos
Esterases , Plásticos , Plásticos/química , Esterases/química , Ensaios de Triagem em Larga Escala , Colorimetria , Biopolímeros
8.
Biopolymers ; 115(4): e23581, 2024 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-38666470

RESUMO

The abstract provides an overview of a study focused on analyzing diverse strategies to achieve sustainable utilization of synthetic polymers through effective waste management. The escalating global consumption of synthetic polymers has precipitated a concerning increase in plastic waste and environmental degradation. To address this challenge, novel materials with specified application goals, such as engineered plastic, have been developed and are intended for recycling and reuse. Despite the reuse and recycling, when plastic gets disposed into the environment, the degradation properties of plastics render a direct disposal hazard, posing a significant environmental threat. To mitigate these issues, the concept of replacing specific monomers of engineered synthetic plastics with bio-alternatives or blending them with other polymers to enhance sustainability and environmental compatibility has emerged. In this study, Acrylonitrile Butadiene Styrene (ABS) plastic is the focal material, and three distinct investigations were conducted. First, replacing ABS plastic's butadiene monomer with natural rubber was explored for its properties and environmental impact. Second, ABS plastic was blended with virgin, recycled, and bio-alternatives of PET (polyethylene terephthalate) and PVC (polyvinyl chloride) polymers. Lastly, recycled ABS blended with recycled PET and PVC was analyzed for mechanical properties. Comparative assessments of these blends were made based on mechanical properties, carbon emissions, and cost-effectiveness. The study determined that the r-ABS/r-PVC (recycled) blend exhibited the most favorable characteristics for practical application.


Assuntos
Polímeros , Reciclagem , Polímeros/química , Butadienos/química , Plásticos/química , Polietilenotereftalatos/química , Cloreto de Polivinila/química , Gerenciamento de Resíduos/métodos
9.
Arch Microbiol ; 206(5): 238, 2024 Apr 30.
Artigo em Inglês | MEDLINE | ID: mdl-38684545

RESUMO

Nanoplastics pose significant environmental problems due to their high mobility and increased toxicity. These particles can cause infertility and inflammation in aquatic organisms, disrupt microbial signaling and act as pollutants carrier. Despite extensive studies on their harmful impact on living organisms, the microbial degradation of nanoplastics is still under research. This study investigated the degradation of nanoplastics by isolating bacteria from the gut microbiome of Tenebrio molitor larvae fed various plastic diets. Five bacterial strains capable of degrading polystyrene were identified, with Achromobacter xylosoxidans M9 showing significant nanoplastic degradation abilities. Within 6 days, this strain reduced nanoplastic particle size by 92.3%, as confirmed by SEM and TEM analyses, and altered the chemical composition of the nanoplastics, indicating a potential for enhanced bioremediation strategies. The strain also caused a 7% weight loss in polystyrene film over 30 days, demonstrating its efficiency in degrading nanoplastics faster than polystyrene film. These findings might enhance plastic bioremediation strategies.


Assuntos
Achromobacter denitrificans , Biodegradação Ambiental , Microbioma Gastrointestinal , Poliestirenos , Animais , Poliestirenos/metabolismo , Achromobacter denitrificans/metabolismo , Plásticos/metabolismo , Plásticos/química , Larva/microbiologia , Microplásticos/metabolismo
10.
Langmuir ; 40(24): 12475-12487, 2024 Jun 18.
Artigo em Inglês | MEDLINE | ID: mdl-38847174

RESUMO

Polymers are the most commonly used packaging materials for nutrition and consumer products. The ever-growing concern over pollution and potential environmental contamination generated from single-use packaging materials has raised safety questions. Polymers used in these materials often contain impurities, including unreacted monomers and small oligomers. The characterization of transport properties, including diffusion and leaching of these molecules, is largely hampered by the long timescales involved in shelf life experiments. In this work, we employ atomistic molecular simulation techniques to explore the main mechanisms involved in the bulk and interfacial transport of monomer molecules from three polymers commonly employed as packaging materials: polyamide-6, polycarbonate, and poly(methyl methacrylate). Our simulations showed that both hopping and continuous diffusion play important roles in inbound monomer diffusion and that solvent-polymer compatibility significantly affects monomer leaching. These results provide rationalization for monomer leaching in model food formulations as well as bulky industry-relevant molecules. Through this molecular-scale characterization, we offer insights to aid in the design of polymer/consumer product interfaces with reduced risk of contamination and longer shelf life.


Assuntos
Embalagem de Alimentos , Difusão , Plásticos/química , Simulação de Dinâmica Molecular , Polimetil Metacrilato/química , Cimento de Policarboxilato/química , Polímeros/química , Contaminação de Alimentos/análise
11.
Biomacromolecules ; 25(5): 2875-2889, 2024 May 13.
Artigo em Inglês | MEDLINE | ID: mdl-38554086

RESUMO

We present a novel group of tryptophan (Trp)-based fluorescent polymeric probes synthesized via ring-opening metathesis polymerization (ROMP) of Trp-derived norbornene monomers. These probes, in mono- and disubstituted forms, incorporate amide and ester anchoring groups. The quantity of Trp substituents did not affect fluorescence selectivity but influenced quenching percentage. Poly-diamide-Trp, Poly-monoamide-Trp, Poly-diester-Trp, and Poly-monoester-Trp probes displayed selective detection of Fe2+ and Fe3+ ions with fluorescence on-off characteristics. Poly-diamide-Trp and Poly-monoamide-Trp exhibited a limit of detection (LOD) for Fe2+ and Fe3+ ions of 0.86-11.32 µM, while Poly-diester-Trp and Poly-monoester-Trp showed higher LODs (21.8-108.7 µM). These probes exhibited high selectivity over Fe2+, a crucial metal ion in the body known for its redox properties causing oxidative stress and cell damage. Cell cytotoxicity tests in various cell types confirmed biocompatibility. Additionally, Poly-diamide-Trp displayed excellent cell permeability and iron ion detection in EA.hy926 cells, suggesting potential for bioimaging and clinical applications.


Assuntos
Corantes Fluorescentes , Ferro , Plásticos , Triptofano , Corantes Fluorescentes/química , Triptofano/química , Triptofano/análise , Humanos , Ferro/química , Ferro/análise , Plásticos/química , Biomarcadores/análise , Polímeros/química , Norbornanos/química
12.
Microb Ecol ; 87(1): 105, 2024 Aug 12.
Artigo em Inglês | MEDLINE | ID: mdl-39133233

RESUMO

Despite some effectiveness of wastewater treatment processes, microplastics accumulate in sewage sludge and their further use may contribute to the release of plastic microplastics into the environment. There is an urgent need to reduce the amount of microplastics in sewage sludge. Plastic particles serve as solid substrates for various microorganisms, promoting the formation of microbial biofilms with different metabolic activities. The biofilm environment associated with microplastics will determine the efficiency of treatment processes, especially biological methods, and the mechanisms of organic compound conversion. A significant source of microplastics is the land application of sewage sludge from wastewater treatment plants. The detrimental impact of microplastics affects soil enzymatic activity, soil microorganisms, flora, fauna, and plant production. This review article summarizes the development of research related to microplastics and discusses the issue of microplastic introduction from sewage sludge. Given that microplastics can contain complex composite polymers and form a plastisphere, further research is needed to understand their potential environmental impact, pathogenicity, and the characteristics of biofilms in wastewater treatment systems. The article also discusses the physicochemical properties of microplastics in wastewater treatment plants and their role in biofilm formation. Then, the article explained the impact of these properties on the possibility of the formation of biofilms on their surface due to the peculiar structure of microorganisms and also characterized what factors enable the formation of specific plastisphere in wastewater treatment plants. It highlights the urgent need to understand the basic information about microplastics to assess environmental toxicity more rationally, enabling better pollution control and the development of regulatory standards to manage microplastics entering the environment.


Assuntos
Biofilmes , Microbiota , Microplásticos , Esgotos , Águas Residuárias , Microplásticos/análise , Águas Residuárias/microbiologia , Águas Residuárias/química , Esgotos/microbiologia , Esgotos/química , Eliminação de Resíduos Líquidos , Poluentes Químicos da Água/análise , Bactérias/classificação , Bactérias/metabolismo , Plásticos/química
13.
J Chem Inf Model ; 64(16): 6492-6505, 2024 Aug 26.
Artigo em Inglês | MEDLINE | ID: mdl-39119989

RESUMO

We developed a Target Plastic Model (TPM) to estimate the critical plastic burden of organic toxicants in five types of plastics, namely, polydimethylsiloxane (PDMS), polyoxymethylene (POM), polyacrylate (PA), low-density polyethylene (LDPE), and polyurethane ester (PU), following the Target Lipid Model (TLM) framework. By substituting the lipid-water partition coefficient in the TLM with plastic-water partition coefficients to create TPM, we demonstrated that the biomimetic nature of these plastic phases allows for the calculation of critical plastic burdens of toxicants, similar to the notion of critical lipid burdens in TLM. Following this approach, the critical plastic burdens of baseline (n = 115), less-inert (n = 73), and reactive (n = 75) toxicants ranged from 0.17 to 51.33, 0.04 to 26.62, and 1.00 × 10-6 to 6.78 × 10-4 mmol/kg of plastic, respectively. Our study showed that PDMS, PA, POM, PE, and PU are similar to biomembranes in mimicking the passive exchange of chemicals with the water phase. Using the TPM, median lethal concentration (LC50) values for fish exposed to baseline toxicants were predicted, and the results agreed with experimental values, with RMSE ranging from 0.311 to 0.538 log unit. Similarly, for the same data set of baseline toxicants, other widely used models, including the TLM (RMSE: 0.32-0.34), ECOSAR (RMSE: 0.35), and the Abraham Solvation Model (ASM; RMSE: 0.31), demonstrated comparable agreement between experimental and predicted values. For less inert chemicals, predictions were within a factor of 5 of experimental values. Comparatively, ASM and ECOSAR showed predictions within a factor of 2 and 3, respectively. The TLM based on phospholipid had predictions within a factor of 3 and octanol within a factor of 4, indicating that the TPM's performance for less inert chemicals is comparable to these established models. Unlike these methods, the TPM requires only the knowledge of plastic bound concentration for a given plastic phase to calculate baseline toxic units, bypassing the need for extensive LC50 and plastic-water partition coefficient data, which are often limited for emerging chemicals. Taken together, the TPM can provide valuable insights into the toxicities of chemicals associated with environmental plastic phases, assisting in selecting the best polymeric phase for passive sampling and designing better passive dosing techniques for toxicity experiments.


Assuntos
Plásticos , Poluentes Químicos da Água , Plásticos/química , Plásticos/toxicidade , Poluentes Químicos da Água/toxicidade , Poluentes Químicos da Água/química , Água/química , Animais
14.
Environ Sci Technol ; 58(3): 1423-1440, 2024 Jan 23.
Artigo em Inglês | MEDLINE | ID: mdl-38197317

RESUMO

Plastic waste has emerged as a serious issue due to its impact on environmental degradation and resource scarcity. Plastic recycling, especially of halogen-containing plastics, presents challenges due to potential secondary pollution and lower-value implementations. Chemical recycling via pyrolysis is the most versatile and robust approach for combating plastic waste. In this Review, we present recent advancements in halogen-plastic pyrolysis for resource utilization and the potential pathways from "reducing to recycling to upcycling" halogens. We emphasize the advanced management of halogen-plastics through copyrolysis with solid wastes (waste polymers, biomass, coal, etc.), which is an efficient method for dealing with mixed wastes to obtain high-value products while reducing undesirable substances. Innovations in catalyst design and reaction configurations for catalytic pyrolysis are comprehensively evaluated. In particular, a tandem catalysis system is a promising route for halogen removal and selective conversion of targeted products. Furthermore, we propose novel insights regarding the utilization and upcycling of halogens from halogen-plastics. This includes the preparation of halogen-based sorbents for elemental mercury removal, the halogenation-vaporization process for metal recovery, and the development of halogen-doped functional materials for new materials and energy applications. The reutilization of halogens facilitates the upcycling of halogen-plastics, but many efforts are needed for mutually beneficial outcomes. Overall, future investigations in the development of copyrolysis and catalyst-driven technologies for upcycling halogen-plastics are highlighted.


Assuntos
Halogênios , Plásticos , Plásticos/química , Pirólise , Reciclagem , Resíduos Sólidos
15.
Environ Sci Technol ; 58(23): 10207-10215, 2024 Jun 11.
Artigo em Inglês | MEDLINE | ID: mdl-38809092

RESUMO

Plastic pollution, a major environmental crisis, has a variety of consequences for various organisms within aquatic systems. Beyond the direct toxicity, plastic pollution has the potential to absorb biological toxins and invasive microbial species. To better understand the capability of environmental plastic debris to adsorb these species, we investigated the binding of the model protein bovine serum albumin (BSA) to polyethylene (PE) films at various stages of photodegradation. Circular dichroism and fluorescence studies revealed that BSA undergoes structural rearrangement to accommodate changes to the polymer's surface characteristics (i.e., crystallinity and oxidation state) that occur as the result of photodegradation. To understand how protein structure may inform docking of whole organisms, we studied biofilm formation of bacteriaShewanella oneidensison the photodegraded PE. Interestingly, biofilms preferentially formed on the photodegraded PE that correlated with the state of weathering that induced the most significant structural rearrangement of BSA. Taken together, our work suggests that there are optimal physical and chemical properties of photodegraded polymers that predict which plastic debris will carry biochemical or microbial hitchhikers.


Assuntos
Plásticos , Soroalbumina Bovina , Soroalbumina Bovina/química , Plásticos/química , Animais , Bovinos , Biofilmes , Polietileno/química , Fotólise
16.
Macromol Rapid Commun ; 45(18): e2400270, 2024 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-39072921

RESUMO

Microwave-assisted pyrolysis of PE to hydrogen and carbon material has great potential to solve the problem of waste PE induced white pollution and provide a promising way to produce hydrogen energy. To increase the hydrogen yield, a new microwave-assisted pyrolysis procedure should be developed. In the present study, a facile double-layer microwave-assisted pyrolysis (DLMP) method is developed to pyrolyze PE. Within this method, PE can be converted to hydrogen, multiwalled carbon nanotubes with extremely high efficiency compared with the traditional methods. A high hydrogen yield of 66.4 mmol g-1 PE is achieved, which is ≈93% of the upper limit of the theoretical hydrogen yield generated from the PE pyrolysis process. The mechanism of high hydrogen yield during the microwave-assisted pyrolysis of PE using the DLMP method is also clarified in detail. The DLMP method paved the potential way for recycling plastic waste into high-value-added products.


Assuntos
Hidrogênio , Micro-Ondas , Nanotubos de Carbono , Plásticos , Pirólise , Reciclagem , Nanotubos de Carbono/química , Hidrogênio/química , Plásticos/química
17.
Macromol Rapid Commun ; 45(17): e2400249, 2024 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-38818529

RESUMO

This review aims to present the different approaches to lessen the environmental impact of the extrusion-based additive manufacturing (MEX) process of thermoplastic-based resins and protect the ecosystem. The benefits and drawbacks of each alternative, including the use of biomaterials or recycled materials as feedstock, energy efficiency, and polluting emissions reduction, have been examined. First, the technological option of using a pellet-fed printer was compared to a filament-fed printer. Then, common biopolymers utilized in MEX applications are discussed, along with methods for improving the mechanical properties of associated printed products. The introduction of natural fillers in thermoplastic resins and the use of biocomposite filaments have been proposed to improve the specific performance of printed items, highlighting the numerous challenges related to their extrusion. Various polymers and fillers derived from recycling are presented as feeding raw materials for printers to reduce waste accumulation, showing the inferior qualities of the resulting goods when compared to printed products made from virgin materials. Finally, the energy consumption and emissions released into the atmosphere during the printing process are discussed, with the potential for both aspects to be controlled through material selection and operating conditions.


Assuntos
Desenvolvimento Sustentável , Impressão Tridimensional , Reciclagem , Plásticos/química , Polímeros/química , Materiais Biocompatíveis/química
18.
Macromol Rapid Commun ; 45(17): e2400200, 2024 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-38875712

RESUMO

Thermosets having low dielectric constant (Dk < 3) and low dielectric dissipation factor (Df < 0.003), high glass transition temperature (Tg > 150 °C), and good adhesion to copper are desirable for the low loss layers of the copper clad laminates (CCL) in next generation printed circuit boards. Three different difunctional diazirines are evaluated for both thermal and photochemical crosslinking of a high Tg vinyl-addition polynorbornene resin: poly(5-hexyl-1-norbornene) (poly(HNB)). The substrate polymer, crosslinked by the carbenes generated from the activated diazirines, forms thermosets with Dk < 2.3 and Df < 0.001 at 10 GHz depending on the identity of the diazirine and the loading. The Dk and Df values for one composition are stable for 1600 h at 125 °C in air and for 1400 h at 85 °C and 85% relative humidity, suggesting good long-term reliability of this thermoset. Adhesion of poly(HNB) to copper can be enhanced by priming the copper surface with a diazirine prior to high temperature lamination; peel strength values of greater than 7.5 N cm-1 are achieved. Negative-tone photopatterning of poly(HNB) with diazirines upon exposure to 365 nm light is demonstrated.


Assuntos
Diazometano , Diazometano/química , Cobre/química , Temperatura , Polímeros/química , Polímeros/síntese química , Norbornanos/química , Estrutura Molecular , Compostos de Vinila/química , Reagentes de Ligações Cruzadas/química , Plásticos/química
19.
Environ Res ; 250: 118558, 2024 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-38412913

RESUMO

The valorization of post-consumer mixed plastics in pyrolysis processes represents an abundant reservoir of carbon that can be effectively converted into useful chars. This process not only holds appeal in terms of improving plastic waste concerns but also contributes to the reduction of greenhouse gas emissions, thus aligning with the principles of a circular economy paradigm. In this study, the char produced from the pyrolysis of post-consumer mixed plastic waste has been activated with Na2CO3, KOH, NaOH, and K2CO3 to improve the textural, structural, and composition characteristics, leading to improved adsorption capability. These characteristics were studied by N2 adsorption-desorption isotherms, scanning electron microscopy, elemental and immediate analysis, and X-ray photoelectron spectroscopy. The developed surface area (SBET) was 573, 939, 704 and 592 m2 g-1 for Na2CO3, KOH, NaOH and K2CO3 activated carbons, respectively. These activated chars (ACs) were tested for the adsorption of heavy metals in both synthetic waters containing Pb, Cd, and Cu and industrial wastewater collected at an agrochemical production plant. Na2CO3-AC was the best performing material. The metal uptake in synthetic waters using a batch set-up was 40, 13 and 12 mg g-1 for Pb, Cd and Cu. Experiments in a column set-up using Na2CO3-AC resulted in a saturation time of 290, 16, and 80 min for Pb, Cd, and Cu synthetic waters, respectively, and metal uptakes of 26.8, 4.1, and 7.9 mg g-1, respectively. The agrochemical effluents, containing mainly Cr, Cu, Mn, and Zn were tested in a plug-flow column. The metal uptake notably decreased compared to synthetic water due to a competition effect for active sites.


Assuntos
Carvão Vegetal , Metais Pesados , Plásticos , Pirólise , Poluentes Químicos da Água , Metais Pesados/química , Plásticos/química , Carvão Vegetal/química , Adsorção , Poluentes Químicos da Água/química , Poluentes Químicos da Água/análise , Águas Residuárias/química
20.
Environ Res ; 255: 119177, 2024 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-38788789

RESUMO

Various plastic materials are used in contact with agricultural soil, like mulching films, crop covers, weed controlling fabrics and nets. Polyethylene (PE) mulches have already been recognized as a significant source of plastic in soil and they have been shown to contain additives like phthalates, known as endocrine disruptors. However, other agricultural plastics are less studied, and little is known on the substances potentially released from them endangering biodiversity and the human health. This research aims to assess whether different agricultural plastics release additives into soil and to compare the release among various materials. We collected soil samples from 38 agricultural fields where conventional mulching films (PE), weed controlling fabrics (PP), biodegradable mulches based on polybutylene adipate terephthalate (PBAT), frost covers (PP), and oxo-degradable films (at least OXO-PE) were used. We analyzed the soils for phthalates and acetyl tributyl citrate (ATBC), used as plastic additives, and for polycyclic aromatic hydrocarbons (PAH) and dodecane that have high affinity for plastics. In comparison to the control soils, dibutylphthalate (DBP) and ATBC concentrations were significantly higher in soils mulched with PE and, partly, with biodegradable films. DBP concentration found in soil samples ranged between below the limit of quantification at a control site (1.5 µg kg-1) to 135 µg kg-1 at a site mulched with OXO-PE. The highest ATBC concentration, 22 ± 6 µg kg-1, was registered in a site mulched with PE, showing a statistically significant difference not only in comparison to the controls but also when compared to sites mulched with OXO-PE (p = 0.029) and PBAT (p < 0.009). On the contrary, the use of agricultural plastics did not influence the concentration of PAHs and dodecane. Our results indicate that agricultural plastics are a source of some organic chemicals to agricultural soils, including phthalates that are known for posing threat to soil ecosystem and human health.


Assuntos
Agricultura , Plásticos Biodegradáveis , Ácidos Ftálicos , Poluentes do Solo , Solo , Ácidos Ftálicos/análise , Poluentes do Solo/análise , Poluentes do Solo/química , Solo/química , Plásticos Biodegradáveis/química , Monitoramento Ambiental/métodos , Plásticos/análise , Plásticos/química
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