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1.
Ecotoxicol Environ Saf ; 283: 116847, 2024 Sep 15.
Artículo en Inglés | MEDLINE | ID: mdl-39128451

RESUMEN

Plastics are widely used worldwide due to their convenience. However, microplastics (MPs) accumulation poses a serious threat to ecosystem health. Therefore, understanding the effects of MPs on living organisms within their native ecosystem is crucial. Previous studies have primarily focused on the impacts of MPs in aquatic environments, whereas the effects of MPs on terrestrial ecosystems have remained largely understudied. Therefore, our study assessed the impacts of MPs on soil ecosystems by characterizing their toxic effects on earthworms (Eisenia fetida). Here, we exposed earthworms to two representative plastics within soil environments: polyvinyl chloride (PVC) and low-density polyethylene (LDPE). Given the known link between MPs and oxidative stress, we next quantified oxidative stress markers and mitochondrial function to assess the effects of MPs on the redox metabolism of earthworms. Mitochondria are crucial metabolic organelles that generate reactive oxygen species via uncontrolled ATP production. Our findings demonstrated that MPs exert different effects depending on their type. Neither the PVC-exposed groups nor the LDPE-exposed groups exhibited changes in oxidative stress, as worked by the action of superoxide dismutase (SOD) and glutathione (GSH). While treatment of the two types of MP did not significantly affect the amount of reactive oxygen species/reactive nitrogen species (ROS/RNS) generated, PVC exhibited a more pronounced effect on antioxidant system compared to LDPE. However, mitochondrial function was markedly decreased in the group exposed to high LDPE concentrations, suggesting that the examined LDPE concentrations were too low to activate compensatory mechanisms. Collectively, our findings demonstrated that exposure of MPs not only influences the antioxidant defense mechanisms of earthworms but also alters their mitochondrial function depending on their types.


Asunto(s)
Glutatión , Microplásticos , Mitocondrias , Oligoquetos , Estrés Oxidativo , Polietileno , Cloruro de Polivinilo , Especies Reactivas de Oxígeno , Contaminantes del Suelo , Animales , Oligoquetos/efectos de los fármacos , Oligoquetos/fisiología , Estrés Oxidativo/efectos de los fármacos , Cloruro de Polivinilo/toxicidad , Mitocondrias/efectos de los fármacos , Mitocondrias/metabolismo , Polietileno/toxicidad , Microplásticos/toxicidad , Contaminantes del Suelo/toxicidad , Especies Reactivas de Oxígeno/metabolismo , Glutatión/metabolismo , Superóxido Dismutasa/metabolismo
2.
Materials (Basel) ; 17(16)2024 Aug 06.
Artículo en Inglés | MEDLINE | ID: mdl-39203076

RESUMEN

In recent decades, plastic waste management has become one of the main environmental challenges for today's society. The excessive consumption of so-called single-use plastics causes continuous damage to ecosystems, and it is necessary to find alternatives to recycle these products. In this work, a mechanical and hygrothermal characterisation of novel plaster composites incorporating LDPE waste in their interior was carried out. Thus, prefabricated plasterboards have been designed with a partial replacement of the original raw material with recycled LDPE in percentages of 5-10-15% by volume. The results show how these new composites exceeded the 0.18 kN minimum breaking load in panels in all cases, while decreases in density and thermal conductivity of up to 15% and 21%, respectively, were obtained. In addition, an increase of 3.8%in thermal resistance was obtained by incorporating these new gypsum boards in lightweight façade walls through simulations. In this way, a new pathway was explored for the recovery of these wastes and their subsequent application in the construction sector.

3.
Appl Environ Microbiol ; 90(7): e0093324, 2024 Jul 24.
Artículo en Inglés | MEDLINE | ID: mdl-38953372

RESUMEN

Starch utilization system (Sus)D-homologs are well known for their carbohydrate-binding capabilities and are part of the sus operon in microorganisms affiliated with the phylum Bacteroidota. Until now, SusD-like proteins have been characterized regarding their affinity toward natural polymers. In this study, three metagenomic SusD homologs (designated SusD1, SusD38489, and SusD70111) were identified and tested with respect to binding to natural and non-natural polymers. SusD1 and SusD38489 are cellulose-binding modules, while SusD70111 preferentially binds chitin. Employing translational fusion proteins with superfolder GFP (sfGFP), pull-down assays, and surface plasmon resonance (SPR) has provided evidence for binding to polyethylene terephthalate (PET) and other synthetic polymers. Structural analysis suggested that a Trp triad might be involved in protein adsorption. Mutation of these residues to Ala resulted in an impaired adsorption to microcrystalline cellulose (MC), but not so to PET and other synthetic polymers. We believe that the characterized SusDs, alongside the methods and considerations presented in this work, will aid further research regarding bioremediation of plastics. IMPORTANCE: SusD1 and SusD38489 can be considered for further applications regarding their putative adsorption toward fossil-fuel based polymers. This is the first time that SusD homologs from the polysaccharide utilization loci (PUL), largely described for the phylum Bacteroidota, are characterized as synthetic polymer-binding proteins.


Asunto(s)
Proteínas Bacterianas , Bacteroidetes , Metagenoma , Proteínas Bacterianas/genética , Proteínas Bacterianas/metabolismo , Bacteroidetes/genética , Bacteroidetes/metabolismo , Celulosa/metabolismo , Polímeros/metabolismo , Quitina/metabolismo , Tereftalatos Polietilenos/metabolismo
4.
Environ Pollut ; 360: 124616, 2024 Nov 01.
Artículo en Inglés | MEDLINE | ID: mdl-39067740

RESUMEN

Microplastics have emerged as pervasive pollutants in aquatic environments, and their interaction with organic contaminants poses a significant environmental challenge. This study aimed to explore the adsorption of micropollutants onto microplastics in a river, examining different plastic materials and the effect of aging on adsorption capacity. Microplastics (low-density polyethylene (LDPE), polyethylene terephthalate (PET), and polyvinyl chloride (PVC)) were introduced into a river stream, and a comprehensive analysis involving 297 organic pollutants was conducted. Passive samplers were deployed to monitor micropollutant presence in the river. Sixty-four analytes were identified in the river flow, with telmisartan being the most prevalent. Nonaged PVC showed the highest telmisartan concentration at 279 ng/g (168 ng/m2 regarding the microplastic surface), while aged PVC exhibited a fourfold decrease. Conversely, aged LDPE preferentially adsorbed metoprolol and tramadol, with concentrations increasing 12- and 3-fold, respectively, compared to nonaged LDPE. Azithromycin and clarithromycin, positively charged compounds, exhibited higher sorption to PET microplastics, regardless of aging. Diclofenac showed higher concentrations on nonaged PVC compared to aged PVC. Aging induced structural changes in microplastics, including color alterations, smaller particle production, and increased specific surface area. These changes influenced micropollutant adsorption, with hydrophobicity, dissociation constants, and the ionic form of pollutants being key factors. Aged microplastics generally showed different sorption properties. A comparison of microplastics and control sand particles indicated preferential micropollutant sorption to microplastics, underscoring their role as vectors for contaminant transport in aquatic ecosystems. Analysis of river sediment emphasized the significance of contact time in pollutant accumulation. Overall, this study provides insights into the complex interactions between microplastics and organic pollutants under environmental conditions and contributes to a better understanding of the fate and behavior of these two types of contaminants in aquatic ecosystems.


Asunto(s)
Monitoreo del Ambiente , Microplásticos , Ríos , Contaminantes Químicos del Agua , Contaminantes Químicos del Agua/análisis , Microplásticos/análisis , Ríos/química , Adsorción
5.
Huan Jing Ke Xue ; 45(6): 3688-3699, 2024 Jun 08.
Artículo en Chino | MEDLINE | ID: mdl-38897788

RESUMEN

The continuous accumulation of microplastics in agricultural soils may affect the natural attenuation of oxygen-containing polycyclic aromatic hydrocarbons (OPAHs). The effects of low-density polyethylene (LDPE) microplastics with the spiking proportion of 1 % and 0.01 % in soils on the natural attenuation of OPAHs were investigated via soil microcosm experiments. The relation between the response of bacterial communities and OPAHs dissipation was also explored. The initial content of OPAHs in the soil was 34.6 mg·kg-1. The dissipation of OPAHs in the soil on day 14 was inhibited by LDPE. The contents of OPAHs in LDPE groups were higher than that in the control by 0.9-1.6 mg·kg-1, and the inhibition degree increased with the proportion of LDPE. The contents of OPAHs were not significantly different among groups on day 28, indicating that the inhibitory effect of LDPE disappeared. LDPE did not change the composition of the dominant taxa in the OPAHs-contaminated soil community but influenced the relative abundances of some dominant taxa. LDPE increased the relative abundance of Proteobacteria and Actinobacteria at the phylum level and decreased that of Bacillus and increased those of Micromonospora, Sphingomonas, and Nitrospira (potential degrading bacteria of LDPE and endogenous substances) at the genus level, all four of which were the main genera dominating intergroup community differences. LDPE changed the α and ß diversity of bacterial communities, but the extents were not significant. LDPE affected the function of the bacterial community, reducing the total abundance of PAHs-degrading genes and some degrading enzymes, inhibiting the growth of PAHs-degrading bacteria and thus interfering with the natural decay of OPAHs.


Asunto(s)
Biodegradación Ambiental , Microplásticos , Hidrocarburos Policíclicos Aromáticos , Polietileno , Microbiología del Suelo , Contaminantes del Suelo , Hidrocarburos Policíclicos Aromáticos/análisis , Contaminantes del Suelo/metabolismo , Contaminantes del Suelo/análisis , Suelo/química , Bacterias/clasificación , Bacterias/metabolismo , Bacterias/crecimiento & desarrollo , Bacterias/efectos de los fármacos , Oxígeno/metabolismo
6.
Int J Mol Sci ; 25(10)2024 May 07.
Artículo en Inglés | MEDLINE | ID: mdl-38791107

RESUMEN

The present study employs X-ray photoelectron spectroscopy (XPS) to analyze plastic samples subjected to degradation processes with the aim to gain insight on the relevant chemical processes and disclose fragmentation mechanisms. Two model plastics, namely polystyrene (PS) and polyethylene (PE), are selected and analyzed before and after artificial UV radiation-triggered weathering, under simulated environmental hydrodynamic conditions, in fresh and marine water for different time intervals. The object of the study is to identify and quantify chemical groups possibly evidencing the occurrence of hydrolysis and oxidation reactions, which are the basis of degradation processes in the environment, determining macroplastic fragmentation. Artificially weathered plastic samples are analyzed also by Raman and FT-IR spectroscopy. Changes in surface chemistry with weathering are revealed by XPS, involving the increase in chemical moieties (hydroxyl, carbonyl, and carboxyl functionalities) which can be correlated with the degradation processes responsible for macroplastic fragmentation. On the other hand, the absence of significant modifications upon plastics weathering evidenced by Raman and FT-IR spectroscopy confirms the importance of investigating plastics surface, which represents the very first part of the materials exposed to degradation agents, thus revealing the power of XPS studies for this purpose. The XPS data on experimentally weathered particles are compared with ones obtained on microplastics collected from real marine environment for investigating the occurring degradation processes.


Asunto(s)
Espectroscopía de Fotoelectrones , Plásticos , Polietileno , Espectroscopía de Fotoelectrones/métodos , Plásticos/química , Polietileno/química , Espectroscopía Infrarroja por Transformada de Fourier/métodos , Espectrometría Raman/métodos , Poliestirenos/química , Contaminantes Químicos del Agua/química , Contaminantes Químicos del Agua/análisis , Agua de Mar/química , Microplásticos/química , Oxidación-Reducción
7.
Heliyon ; 10(1): e23301, 2024 Jan 15.
Artículo en Inglés | MEDLINE | ID: mdl-38205301

RESUMEN

Today, the use of X-rays in diagnosing and sometimes treating patients is inevitable. Despite the many benefits of using X-rays in medical and other sciences, the harmful effects of this radiation on human tissue should not be neglected. One of the best ways to prevent the harmful effects of X-rays on the human body is to use appropriate covers against these rays. It seems that it is necessary to find effective particles to weaken X-rays and choose a suitable substrate with high mechanical resistance to scatter particles in it. In this study, the synthesis of SnO2 nanoparticles from SnCl2.2H2O precursor and BaSO4 nanoparticles from BaCl2.2H2O precursor using neem tree extract (Azadirachta indica) as a reducing and stabilizing agent is reported. After the synthesis of nanoparticles, their structure was investigated by X-ray diffraction, scanning electron microscopy and energy dispersive X-ray analysis. Then the desired composite and nanocomposite were prepared in the polymer substrate. The sheets were prepared using an extruder and then a hot hydraulic press. The output sheets had a thickness of 1 mm. The structural characteristics of the produced sheets such as surface morphology, density of prepared composites, mechanical properties, thermal gravimetric analysis and retention of loaded particles after three times washes were investigated. The X-ray attenuation capability of each sample was evaluated by calculating the linear attenuation coefficient for each prepared sample. The results show that all sheets filled with tin and barium micro and nano particles have more X-ray attenuation capabilities than pure polymer. Among the prepared sheets, the nanocomposite prepared from low-density polyethylene (77 %) + SnO2 (10 %) + BaSO4 (10 %) + multi-walled carbon nanotubes (3 %) showed the highest X-ray attenuation.

8.
J Hazard Mater ; 464: 133014, 2024 02 15.
Artículo en Inglés | MEDLINE | ID: mdl-37984146

RESUMEN

Nanoplastics (NPs, <1 µm) pose greater risks due to their increased absorption rates in biological systems. In this study, we investigated the release of NPs from paper cups and microwavable food containers coated with low-density polyethylene (LDPE) and polylactic acid (PLA). For disposable paper cups, we found that LDPE-coated cups released up to 26-fold more NPs (maximum 1.9 × 107 per cup) than PLA-coated ones. The NPs release from LDPE-coated cups was increased at high temperatures above 80 °C, and further increased by physical agitation. However, negligible NP release was observed when the inner coating thickness exceeded 1 mm. For microwavable food containers, those with PLA coatings were more susceptible to the effects of microwave. Depending on the cooking time, we noticed a significant difference (up to 40000 times) in the number of released NPs between LDPE and PLA coatings. Additionally, higher microwave power level led to an increase of NPs, even with constant total energy input. Considering the release of NP, PLA coatings for disposable paper cups and LDPE coatings for microwavable food containers seem more suitable. Furthermore, our results suggest that multi-use cups significantly reduce NPs release due to their material thickness, making them a safer alternative to disposable ones.


Asunto(s)
Embalaje de Alimentos , Microplásticos , Polietileno , Poliésteres
9.
Bull Environ Contam Toxicol ; 112(1): 19, 2023 Dec 24.
Artículo en Inglés | MEDLINE | ID: mdl-38142453

RESUMEN

Every year, human activities introduce large amounts of synthetic plastics into the environment. Decomposition of the plastic derivatives is very difficult and time consuming, so it is essential to eliminate these pollutants using different methods. Bioremediation, is suitable option, because of the low cost and environmentally safe. In this research, degradation of low-density polyethylene (LDPE) was investigated by two strains, isolated from Hamadan province (Iran) landfill soil. After identification by 16sr DNA primers, their abilities of polyethylene biodegradation were examined by Fourier transform infrared (FTIR), SEM and Gas Chromatography-Mass Spectrometry (GC-MS). Using media contain polyethylene) after and before addition of bacteria), toxicity test was conducted by measuring the germination index, root and hypocotyl length of Lactuca sativa seed. After three months, 10.15% ± 1.04 weight loss of LDPE achieved through strain Stenotrophomonas sp. degradation. Both strains had high biofilm formation capacity, confirmed by Electron microscope images and FTIR analysis. GC-MS confirmed the presence of the end-product of LDPE degradation (Pentacosane, Hexacosane, and Octadecane). Both, Stenotrophomonas sp. and Alcaligenaceae bacterium had significant detoxification ability. In media contain LDPE (without bacteria), decrease in the germination of lettuce seeds was observed.


Asunto(s)
Contaminantes Ambientales , Polietileno , Humanos , Polietileno/química , Biodegradación Ambiental , Stenotrophomonas/metabolismo , Bacterias/metabolismo , Contaminantes Ambientales/metabolismo , Plásticos
10.
Microbiol Res ; 274: 127425, 2023 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-37348445

RESUMEN

Plastic-enriched sites like landfills have immense potential for discovery of microbial consortia that can efficiently degrade plastics. In this study, we used a combination of culture enrichment, high-throughput PacBio sequencing of 16 S rRNA and the ITS gene, Fourier transform infrared (FTIR), and scanning electron microscopy (SEM) to examine the compositional and diversity perturbations of bacterial and fungal consortia from landfill soils and their impact on low-density polyethylene (LDPE) film biodegradation over a 90-day period. Results showed that enrichment cultures effectively utilized LDPE as a carbon source for cellular growth, resulting in significant weight reduction (22.4% and 55.6%) in the films. SEM analysis revealed marked changes in the micrometric surface characteristics (cracks, fissures, and erosion) and biofilm formation in LDPE films. FTIR analyses suggested structural and functional group modification related to C-H (2831-2943 cm⁻¹), and CH2 (1400 cm⁻¹) stretching, CO and CC (680-950 cm⁻¹) scission, and CO incorporation (3320-3500 cm⁻¹) into the carbon backbone, indicative of LDPE polymer biodegradation. Enrichment cultures had lower diversity and richness of microbial taxa compared to soil samples, with LDPE as a carbon source having a direct influence on the structure and functioning of the microbial consortia. A total of 26 bacterial and 12 fungal OTU exhibiting high relative abundance and significant associations (IndVal > 0.7, q < 0.05) were identified in the enrichment culture. Bacterial taxa such as unclassified Parvibaculum FJ375498, Achromobacter xylosoxidans, unclassified Chitinophagaceae PAC002331, unclassified Paludisphaera and unclassified Comamonas JX898122, and six fungal species (Galactomyces candidus, Trichosporon chiropterorum, Aspergillus fumigatus, Penicillium chalabudae, Talaromyces thailandensis, and Penicillium citreosulfuratum) were identified as the putative LDPE degraders in the enrichment microbial consortium cultures. PICRUSt2 metagenomic functional profiling of taxonomic bacterial taxa abundances in both landfill soil and enrichment microbial consortia also revealed differential enrichment of energy production, stress tolerance, surface attachment and motility pathways, and xenobiotic degrading enzymes important for biofilm formation and hydrolytic/oxidative LDPE biodegradation. The findings shed light on the composition and structural changes in landfill soil microbial consortia during enrichment with LDPE as a carbon source and suggest novel LDPE-degrading bacterial and fungal taxa that could be explored for management of polyethylene pollution.


Asunto(s)
Polietileno , Suelo , Polietileno/química , Polietileno/metabolismo , Bacterias/genética , Bacterias/metabolismo , Análisis Multivariante , Plásticos/metabolismo , Biodegradación Ambiental , Instalaciones de Eliminación de Residuos , Carbono/metabolismo
11.
Eur J Pharm Sci ; 172: 106138, 2022 May 01.
Artículo en Inglés | MEDLINE | ID: mdl-35122951

RESUMEN

By neglecting the kinetics of leaching, accumulation of leachables in a clinically relevant medium in contact with plastics is principally driven by the equilibrium partition coefficient between the polymer and the medium phase. Based on experimental partition coefficients for a wide set of chemically diverse compounds between low density polyethylene (LDPE) and water, a linear solvation energy relationship (LSER) model was obtained in part I of this study, reading: logKi,LDPE/W=-0.529+1.098Ei-1.557Si-2.991Ai-4.617Bi+3.886Vi. The model was proven accurate and precise (n = 156, R2 = 0.991, RMSE = 0.264). In this part II of the study, for further evaluation and benchmarking of the LSER model ∼ 33% (n = 52) of the total observations were ascribed to an independent validation set. Calculation of partition coefficients logKi,LDPE/W for this validation set was based on experimental LSER solute descriptors. Linear regression against the corresponding experimental values yielded R2 = 0.985 and RMSE = 0.352. When using LSER solute descriptors predicted from the compound's chemical structure by means of a QSPR prediction tool, instead, R2 = 0.984 and RMSE = 0.511 were obtained. These statistics are considered indicative for extractables with no experimental LSER solute descriptors available. By comparison to LSER models from the literature, a strong correlation between the quality of experimental partition coefficients and the chemical diversity of the training set to the model's predictability was observed, the latter of particular relevance for the application domain of the model. Further, to tentatively match partitioning into LDPE to partitioning into a liquid phase, partition coefficients logKi,LDPE/W were converted into logKi,LDPEamorph/W by considering the amorphous fraction of the polymer as effective phase volume only. A LSER model now recalibrated based on the observations for logKi,LDPEamorph/W exhibited the constant in the equation above to now read -0.079 instead of -0.529 which rendered the model more similar to a corresponding LSER-model for n-hexadencane/water. Based on LSER system parameters available, the sorption behavior of LDPE could be efficiently compared to the one of polydimethylsiloxane (PDMS), polyacrylate (PA) and polyoxymethylene (POM). The latter, by offering capabilities for polar interactions due to their heteroatomic building blocks, exhibit stronger sorption than LDPE to the more polar, non-hydrophobic domain of sorbates up to an logKi,LDPE/W range of 3 to 4. Above that range, all four polymers exhibited a roughly similar sorption behavior. Overall, LSERs were found to represent an accurate and user-friendly approach for the estimation of equilibrium partition coefficients involving a polymeric phase. All intrinsic input parameters can be retrieved from a free, web-based and curated database along with the outright calculation of the partition coefficient for any given neutral compound with a known structure for a given two-phased system.


Asunto(s)
Polietileno , Agua , Benchmarking , Cinética , Polietileno/química , Soluciones , Agua/química
12.
J Colloid Interface Sci ; 613: 709-719, 2022 May.
Artículo en Inglés | MEDLINE | ID: mdl-35066230

RESUMEN

The evaporation of a colloidal droplet on a solid surface produces a ring-like structure at the pinned contact line due to induced capillary flow, also known as the coffee-ring effect (CRE). However, the addition of certain additives can significantly reduce CRE, whose physical origin remains in debate. In this study, the time-resolved low field (LF)-NMR technique highlights the effect of different water fractions in colloidal droplets on the ultimate distribution of silica nanoparticles during evaporation. With the assistance of 1H T2 relaxometry, the impact of decreasing evaporation rate (J) and additives on the fractions of bound, trapped, and free water can be obtained. Utilizing the T2 Carr-Purcell-Meiboom-Gill (CPMG) sequence approach, in-situ tracking during droplets evaporation, with varying J, was obtained to conclude the minimum existence time of bound water required during evaporation for CRE suppression. As the droplet J decreases, the competition between the time scale of totally droplet evaporation tF and the time spent of bound water during evaporation tB may influence the ring formation. Experimentally a shorter duration of tB/tF ≤ 0.5 is required for formating the coffee ring structure and successfully suppressed when its existence time surpasses a particular threshold ≥ 0.5.


Asunto(s)
Nanopartículas , Agua , Fenómenos Físicos , Dióxido de Silicio
13.
Arch Microbiol ; 204(1): 74, 2021 Dec 24.
Artículo en Inglés | MEDLINE | ID: mdl-34951695

RESUMEN

Enterobacter cloacae AKS7 was previously reported to degrade UV-treated low-density polyethylene (LDPE) more efficiently than UV-untreated LDPE. However, the degradation of LDPE by Enterobacter cloacae AKS7 at the LDPE-contaminated soil remained unaddressed. To address this issue, soil microcosms were prepared in which an equal amount of either UV-treated or UV-untreated LDPE was added. Then, the microcosms were either augmented with AKS7 or left non-augmented. We observed that the bioaugmented microcosms exhibited approximately twofold greater polymer degradation than non-bioaugmented microcosms. To investigate the underlying cause, we found that the abundance of LDPE-degrading organisms got increased by approximately fivefold in bioaugmented microcosms than non-bioaugmented microcosms. The microbial biomass carbon and nitrogen content got enhanced by approximately twofold in bioaugmented microcosms as contrasted to non-bioaugmented microcosms. Furthermore, the bioaugmented microcosms showed almost twofold increase in the level of dehydrogenase and fluorescein diacetate (FDA) hydrolyzing activity than the non-bioaugmented microcosms. To add on, Shannon-diversity index and Gini coefficient were determined in each microcosm to measure the microbial richness and evenness, respectively, using the results of carbon source utilization pattern of BiOLOG ECO plate. The bioaugmented microcosms exhibited ~ 30% higher functional richness and ~ 30% enhanced functional evenness than the non-bioaugmented microcosms indicating the formation of an enriched ecosystem that could offer various functions including polymer degradation. Taken together, the results suggested that Enterobacter cloacae AKS7 could be used as a promising bioaugmenting agent for the sustainable degradation of LDPE waste at a contaminated site.


Asunto(s)
Polietileno , Contaminantes del Suelo , Biodegradación Ambiental , Ecosistema , Enterobacter cloacae , Suelo , Microbiología del Suelo
14.
Polymers (Basel) ; 13(20)2021 Oct 19.
Artículo en Inglés | MEDLINE | ID: mdl-34685356

RESUMEN

Due to its relatively simple structure, low-density polyethylene (LDPE) can be considered as a model polymer for the study of its properties. Herein, the effect of processing variables on the microstructure and crystallinity of injection-molded LDPE specimens was quantitatively determined. The polymer was injected at different temperature conditions in the barrel and the mold. The specimens were characterized by scanning electron microscopy and X-ray diffraction. With the data obtained, an analysis of variance (ANOVA) was carried out, and response surface graphs (SRP) were constructed to quantify and to observe the behavior of the processing variables, respectively. Different models were obtained to predict the effect of the experimental factors on the response variables. The results showed that the interaction of the two temperatures has the greatest effect on the size of the spherulite, while the temperature of the mold affects the crystallinity. The SRP showed different behaviors: for the spherulite, the size increases with the mold temperature, while for the crystallinity, higher values were observed at an intermediate mold temperature and a low melt temperature. The results presented herein are valuable for setting empirical relations between the microstructure, crystallinity, and the molding conditions of LDPE.

15.
J Hazard Mater ; 414: 125521, 2021 07 15.
Artículo en Inglés | MEDLINE | ID: mdl-34030405

RESUMEN

Intensive use of low-density polyethylene (LDPE) plastic films in agro-ecosystems has raised considerable concerns due to the increasing film residues in soils. It is unclear how the increased film residues affect soil properties and crop productivity and whether biodegradable (Bio) film can substitute LDPE. To address the issue, we designed a landfill experiment with different addition levels of plastic residue into soils of maize (Zea mays L.) field from 2018 to 2019. Six treatments were arranged as PMT1-T3/BioT1-T3, representing the low, medium, and high-level application of LDPE / Bio film fragments, with no residual film, applied as CK. Results show that, soil bulk density was significantly increased from 1.19 to 1.31 g/cm3 regardless of residue types. In contrast, soil porosity was lowered from 58.03% in CK to 57.36% in Bio and 56.12% in LDPE significantly (P < 0.05). Increased residues improved soil nitrogen level and lowered the C/N ratio significantly. Also, it decreased microbial biomass C and N levels but with no change in C/N (P < 0.05). Maize yield and WUE decreased, while soil water storage increased significantly. LDPE residues affected soil properties and productivity partly lower than Bio ones did, but the negative effects of them were similar in the maize field.


Asunto(s)
Ecosistema , Suelo , Agricultura , China , Plásticos , Zea mays
16.
Adv Mater ; 33(27): e2100714, 2021 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-34048610

RESUMEN

Poly(3-hexylthiophene) (P3HT) is found to be a highly effective conductivity-reducing additive for low-density polyethylene (LDPE), which introduces a new application area to the field of conjugated polymers. Additives that reduce the direct-current (DC) electrical conductivity of an insulation material at high electric fields have gained a lot of research interest because they may facilitate the design of more efficient high-voltage direct-current power cables. An ultralow concentration of regio-regular P3HT of 0.0005 wt% is found to reduce the DC conductivity of LDPE threefold, which translates into the highest efficiency reported for any conductivity-reducing additive to date. The here-established approach, i.e., the use of a conjugated polymer as a mere additive, may boost demand in absolute terms beyond the quantities needed for thin-film electronics, which would turn organic semiconductors from a niche product into commodity chemicals.

17.
Molecules ; 26(9)2021 Apr 26.
Artículo en Inglés | MEDLINE | ID: mdl-33925792

RESUMEN

Low-density polyethylene (LDPE) sheets (3.0 ± 0.1 cm) received sequential treatment, first by the action of direct-current low-pressure plasma (DC-LPP) with a 100% oxygen partial pressure, 3.0 × 10-2 mbar pressure, 600 V DC tension, 5.6 cm distance, 6-min treatment. Then, sheets were submitted to TiO2 photocatalysis at UV radiation at 254 nm (TiO2/UV) with a pH value of 4.5 ± 0.2 and a TiO2 concentration of 1 gL-1. We achieved a complementary effect on the transformation of LDPE films. With the first treatment, ablation was generated, which increased hydrophilicity. With the second treatment, the cavities appeared. The changes in the LDPE sheets' hydrophobicity were measured using the static contact angle (SCA) technique. The photocatalytic degradation curve at 400 h revealed that the DC-LPP photocatalysis sequential process decreased SCA by 82°. This was achieved by the incorporation of polar groups, which increased hydrophilicity, roughness, and rigidity by 12 and 38%, respectively. These sequential processes could be employed for LDPE and other material biodegradation pretreatment.

18.
Materials (Basel) ; 14(7)2021 Apr 05.
Artículo en Inglés | MEDLINE | ID: mdl-33916414

RESUMEN

Achieving good quality of products from plastic injection moulding processes is very challenging, since the process comprises many affecting parameters. Common defects such as warpage are hard to avoid, and the defective parts will eventually go to waste, leading to unnecessary costs to the manufacturer. The use of recycled material from postindustrial waste has been studied by a few researchers. However, the application of an optimisation method by which to optimise processing parameters to mould parts using recycled materials remains lacking. In this study, Response Surface Methodology (RSM) and Particle Swarm Optimisation (PSO) methods were conducted on thick plate parts moulded using virgin and recycled low-density polyethylene (LDPE) materials (100:0, 70:30, 60:40 and 50:50; virgin to recycle material ratios) to find the optimal input parameters for each of the material ratios. Shrinkage in the x and y directions increased in correlation with the recycled ratio, compared to virgin material. Meanwhile, the tensile strength of the thick plate part continued to decrease when the recycled ratio increased. R30 (70:30) had the optimum shrinkage in the x direction with respect to R0 (100:0) material where the shrinkage increased by 24.49% (RSM) and 33.20% (PSO). On the other hand, the shrinkage in the y direction for R30 material increased by 4.48% (RSM) and decreased by 2.67% (PSO), while the tensile strength of R30 (70:30) material decreased by 0.51% (RSM) and 2.68% (PSO) as compared to R0 (100:0) material. Validation tests indicated that the optimal setting of processing parameter suggested by PSO and RSM for R0 (100:0), R30 (70:30), R40 (60:40) and R50 (50:50) was less than 10%.

19.
Data Brief ; 34: 106622, 2021 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-33354603

RESUMEN

Agricultural waste mapping is an indispensable tool for the development and adoption of sustainable waste management practises in the agricultural sector. Current practices of agricultural plastic waste (APW) management in countries with large agricultural areas and thus high generation volumes of APW include uncontrollable disposal in fields or near water sources, or uncontrolled burning of the waste. These practices lead to irreversible deterioration of the natural environment through land and soil contamination, contamination of freshwater resources, air pollution and also pose public health issues. Given these negative effects on the environment, spatial prediction of APW generation becomes significant in sustainable agriculture. This dataset consists of the coordinates of the agricultural plots identified in the Republic of Cyprus and the area in square meters covered by agricultural greenhouses. The dataset has been used to perform APW generation mapping and predict the national generation quantities of waste low- density polyethylene (LDPE). The collection of the data is included in sixteen tables separated per geographical area-cluster. The agricultural plastic waste (APW) generation mapping was conducted with the use of up-to-date statistics from Cyprus Agricultural Payments Organization (CAPO), geographic information system (GIS) and satellite imagery.

20.
Materials (Basel) ; 13(17)2020 Sep 01.
Artículo en Inglés | MEDLINE | ID: mdl-32882906

RESUMEN

Antioxidant packaging is an effective method to protect oxygen-sensitive food from oxidation. In order to concurrently obtain a storage stability and excellent oxygen scavenging of antioxidant film for the high moisture food, a moisture activating oxygen scavenging film was prepared by using tea polyphenols as the oxygen scavenger. The moisture activating function was achieved by introducing the ß-cyclodextrin embedding technology, and the tea polyphenols-ß-cyclodextrin inclusion complex was co-extruded with low-density polyethylene (LDPE) to improve the storage stability. The results indicate that the tea polyphenols is well embedded by ß-cyclodextrin according to the Fourier transform infrared spectra (FT-IR), and a relatively homogeneous dispersion of oxygen scavenger is observed while the oxygen scavenger content is less than 5%. The oxygen scavenging increases with the increase of oxygen scavenger from 1% to 5%, and a maximal oxygen absorption of 0.0150 mol/m2 is exhibited at oxygen scavenger content value of 5%. Then, the oxygen scavenging significantly decrease under the oxygen scavenger content of 7% and 10%. Moreover, the oxygen scavenging amount sharply increase after steeping in water or storage in extremely high humidity of RH 84% while the oxygen scavenging is restrained under RH 32-75%, indicating that the moisture activating oxygen scavenging is functioning. The oxygen scavenging is obvious restrained under low temperature of 4 °C while the oxygen scavenging is activated at 23 °C and 50 °C with similar oxygen scavenging amount. Besides, both of the tensile and heat-sealing strength deteriorative with the increase of oxygen scavenger content, while they are acceptable at oxygen scavenger content of 5%. Finally, the prepared oxygen scavenging film was used for packaging orange juice and received a good antioxidant effect. Thus, the acquired moisture activating oxygen scavenging film has a good stability under regular storage condition, and shows a potentially application for oxygen-sensitive food with high moisture content.

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