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1.
ACS Appl Mater Interfaces ; 13(1): 1398-1412, 2021 Jan 13.
Artigo em Inglês | MEDLINE | ID: mdl-33398990

RESUMO

Nanotechnology-based packaging may improve food quality and safety, but packages manufactured with polymer nanocomposites (PNCs) could be a source of human dietary exposure to engineered nanomaterials (ENMs). Previous studies showed that PNCs release ENMs to foods predominantly in a dissolved state, but most of this work used food simulants like dilute acetic acid and water, leaving questions about how substances in real foods may influence exposure. Here, we demonstrate that food and beverage ingredients with reducing properties, like sweeteners, may alter exposure by inducing nanoparticle formation in foods contacting silver nanotechnology-enabled packaging. We incorporated 12.8 ± 1.4 nm silver nanoparticles (AgNPs) into polyethylene and stored media containing reducing ingredients in packages manufactured from this material under accelerated room-temperature and refrigerated conditions. Analysis of the leachates revealed that reducing ingredients increased the total silver transferred to foods contacting PNC packaging (by as much as 7-fold) and also induced the (re)formation of AgNPs from this dissolved silver during storage. AgNP formation was also observed when Ag+ was introduced to solutions of natural and artificial sweeteners (glucose, sucrose, aspartame), commercial beverages (soft drinks, juices, milk), and liquid foods (yogurt, starch slurry), and the amount and morphology of reformed AgNPs depended on the ingredient formulation, silver concentration, storage conditions, and light exposure. These results imply that food and beverage ingredients may influence dietary exposure to nanoparticles when PNCs are used in packaging applications, and the practice of using food simulants may in certain cases underpredict the amount of ENMs likely to be found in foods stored in these materials.


Assuntos
Bebidas , Embalagem de Alimentos , Nanopartículas Metálicas/química , Prata/química , Animais , Aspartame/química , Temperatura Baixa , Contaminação de Alimentos/análise , Glucose/química , Nanopartículas Metálicas/análise , Oxirredução , Polietileno/química , Prata/análise , Amido/química , Sacarose/química , Edulcorantes/química , Iogurte
2.
ACS Appl Mater Interfaces ; 13(2): 2483-2495, 2021 Jan 20.
Artigo em Inglês | MEDLINE | ID: mdl-33404219

RESUMO

Influenza, pneumonia, and pathogenic infection of the respiratory system are boosted in cold environments. Low temperatures also result in vasoconstriction, restraint of blood flow, and decreased oxygen to the heart, and the risk of a heart attack would increase accordingly. The present face mask fabric fails to preserve its air-filtering function as its electrostatic function vanishes once exposed to water. Therefore, its filtering efficacy would be decreased meaningfully, making it nearly impracticable to reuse the disposable face masks. The urgent requirement for photothermal fabrics is also rising. Nanobased polyethyleneimine-polypyrrole nanopigments (NPP NPs) have been developed and have strong near-infrared spectrum absorption and exceptional photothermal convertible performance. Herein, the mask fabric used PE-fiber-constructed membrane (PEFM) was coated by the binding affinity of the cationic polyethyleneimine component of NPP NPs forming NPP NPs-PEFM. To the best of our knowledge, no study has investigated NPP NP-coated mask fabric to perform infrared red (solar or body) photothermal conversion efficacy to provide biocompatible warming, remotely photothermally captured antipathogen, and antivasoconstriction in vivo. This pioneering study showed that the developed NPP NPs-PEFM could be washable, reusable, breathable, biocompatible, and photothermal conversable for active eradication of pathogenic bacteria. Further, it possesses warming preservation and antivasoconstriction.


Assuntos
Materiais Revestidos Biocompatíveis/química , Nanoestruturas/química , Polietileno/química , Polietilenoimina/química , Polímeros/química , Pirróis/química , Têxteis/análise , Animais , Antibacterianos/química , Raios Infravermelhos , Máscaras/microbiologia , Nanoestruturas/ultraestrutura , Processos Fotoquímicos , Coelhos , Ratos , Temperatura , Têxteis/microbiologia
3.
Ecotoxicol Environ Saf ; 209: 111781, 2021 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-33340954

RESUMO

Compared with pristine agricultural polyethylene (PE) soil films microplastics (MPs), aged agricultural polyethylene (APE) soil films MPs have a rougher surface, more cracks and have some oxygen-containing functional groups that makes them adsorb organic pollutants, such as pesticides more easily. This may be more harmful to human beings than marine MPs as the agricultural soil films are closer to our living environment. But few works focused on the adsorption of pesticides on pristine or aged agricultural polyethylene soil films MPs. In order to promote the risk assessment of co-exposure of pesticides and agricultural polyethylene soil films MPs, a comparative study on the adsorption behavior and mechanism of four pesticides (carbendazim, diflubenzuron, malathion, difenoconazole) by pristine PE MPs and APE MPs were carried out in this paper. The results showed microcracks and surface oxidation observed on APE MPs. The adsorption kinetics and isotherm models indicated that the adsorption capacity of APE MPs was higher than that of PE MPs, which attribute to the larger surface area of APE MPs. The adsorption capacities of pesticides on APE MPs were positively correlated with LogKow (Water octanol partition coefficient) values of these four pesticides, showed the hydrophobic partitioning played the most important part in the adsorption, but also some H-bonding between secondary amines in the molecular of diflubenzuron and polar O-containing functional groups on APE MPs may be formed. And electrostatic forces or interactions are not the determining factor for these pesticides adsorption behavior of PE MPs, and the effect of pH is mainly driven by changes in sorbate properties rather than changes in surface properties of MPs. The results presented herein show the APE MPs can be a better vector of most hydrophobic pesticides than pristine MPs in the agricultural field, and more attention should be paid to the problem of films and pesticides residue in farmland soil.


Assuntos
Agricultura , Microplásticos/química , Praguicidas/química , Polietileno/química , Poluentes do Solo/química , Adsorção , Dioxolanos , Poluentes Ambientais , Humanos , Interações Hidrofóbicas e Hidrofílicas , Cinética , Plásticos/química , Solo/química , Triazóis , Água
4.
Chemosphere ; 263: 127976, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-32835979

RESUMO

The presence of both pollutants: microplastics and pharmaceutical residues in various environmental compartments is an issue of increasing concern. Available literature data indicates that microplastics can affect the environmental distribution and transport of e.g. persistent organic pollutants (POPs) through sorption interactions, concentrating them at a given point and thus influencing the environmental risks represented by the sorbent and sorbate pair. Therefore, their potential to change the fate of other contaminants in the environment, such as pharmaceuticals, is worth investigating. The aim of this study was to evaluate the sorption capacity of nine pharmaceuticals, commonly used in human and veterinary medicine, which constitute known ubiquitous water pollutants: enrofloxacin (ENR), ciprofloxacin (CIP), norfloxacin (NOR), 5-fluorouracil (5-FU), methotrexate (MET), flubendazole (FLU), fenbendazole (FEN), propranolol (PRO) and nadolol (NAD), on the surface of the most often identified microscopic plastic particles in the aquatic environment, i.e. polypropylene (PP), low density polyethylene (LD-PE), high density polyethylene (HD-PE) and polyvinyl chloride (PVC). The obtained results suggest a complex nature of sorption, including both hydrophobic and electrostatic interactions. However, since the ionic strength of the medium was found to be a significant factor influencing the sorption potential, minute interactions are observed in conditions common for the natural environment.


Assuntos
Microplásticos/química , Preparações Farmacêuticas/química , Poluentes Químicos da Água/química , Adsorção , Interações Hidrofóbicas e Hidrofílicas , Plásticos , Polietileno/química , Polipropilenos/química , Cloreto de Polivinila/química , Eletricidade Estática
5.
J Surg Oncol ; 123(4): 1126-1133, 2021 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-33373471

RESUMO

INTRODUCTION: All-polyethylene (AP) tibial components have demonstrated equivalent or improved long-term survivorship and reduced cost compared with metal-backed (MB) components in primary total knee arthroplasty; however, there is a lack of data comparing these outcomes in the setting of an oncologic endoprosthetic reconstruction. METHODS: A total of 115 (88 AP:27 MB) patients undergoing cemented distal femur endoprosthetic reconstruction following oncologic resection were reviewed. Mean age was 40 years and 51% were females. Cumulative incidences of all-cause revision, tibial component revision, reoperation, and infection were calculated utilizing a competing risk analysis with death as the competitor. Mean follow-up was 14 years. RESULTS: The 10-year cumulative incidence of all-cause revision was 19.9% in the AP group and 16.3% in the MB group (hazard ratio [HR] = 0.93, p = 0.88). The cumulative incidence of tibial component revision was significantly lower in AP compared with MB at 10 years (1.1% vs. 12.5%, HR = 0.18, p = 0.03). There was no difference in infection-free survival when comparing the two groups (p = 0.72). CONCLUSIONS: Reconstruction utilizing an MB or AP tibia component resulted in equivalent overall outcome; however, the tibial component in the AP group was less likely to be revised. AP tibial component should be considered for all primary oncologic reconstructions in the distal femur. LEVEL OF EVIDENCE: Level III Therapeutic.


Assuntos
Neoplasias Femorais/cirurgia , Complicações Pós-Operatórias/epidemiologia , Procedimentos Cirúrgicos Reconstrutivos/métodos , Reoperação/métodos , Infecção da Ferida Cirúrgica/epidemiologia , Tíbia/cirurgia , Adulto , Feminino , Neoplasias Femorais/patologia , Seguimentos , Humanos , Prótese do Joelho , Masculino , Metais/química , Recidiva Local de Neoplasia/patologia , Recidiva Local de Neoplasia/cirurgia , Polietileno/química , Prognóstico , Estudos Prospectivos , Estados Unidos/epidemiologia
6.
Chemosphere ; 261: 128179, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-33113649

RESUMO

Understanding how wastewater treatment plants (WWTPs) process microplastics (MPs) will help informing management practices to reduce MP emissions to the environment. We show that composite 24 h samples taken at three replications from the outflow of the grit chamber, primary settling tank and clarifier of the WWTP of Sari City, on the southern coast of the Caspian Sea, contained 12667 ± 668, 3514 ± 543 and 423 ± 44.9 MP/m3, respectively. Fibers accounted for 94.9%, 89.9% and 77.5% of the total number of MPs, respectively. The MP removal efficiency was 96.7%. MP shape (fiber, particle), size and structure were the most important factors determining their removal in different steps of the wastewater treatment process. The structure of microfibers (polyester, acrylic and nylon) and the consequent higher density than water explained their high removal (72.3%) in the primary settling tank. However, size was more important in microparticle removal with particles ≥500 µm being removed in the primary settling tank and <500 µm in the clarifier unit. The smallest particles (37-300 µm) showed the lowest removal efficiency. The predominant types of fibers and particles were polyester and polyethylene, respectively, which are likely to originate from the washing of synthetic textiles and from microbeads in toothpaste and cosmetics. Despite the efficiency of the Sari WWTP in removing MPs, it remains a major emission source of MPs to the Caspian Sea due to its high daily discharge load.


Assuntos
Microplásticos/isolamento & purificação , Eliminação de Resíduos Líquidos/métodos , Poluentes Químicos da Água/isolamento & purificação , Mar Cáspio , Cidades , Irã (Geográfico) , Microplásticos/química , Nylons/química , Nylons/isolamento & purificação , Poliésteres/química , Poliésteres/isolamento & purificação , Polietileno/química , Polietileno/isolamento & purificação , Têxteis , Águas Residuárias/química , Poluentes Químicos da Água/química
7.
Chemosphere ; 261: 128186, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-33113661

RESUMO

Although microplastics (MPs; < 5 mm) have been recognized as one of the most challenging environmental pollutants in the ocean, our understanding of the environmental fate of freshwater MPs falls far behind, particularly on smaller MPs (<0.1 mm). Here, we seek to reveal the latest MP pollution status in the largest freshwater lake of China, Poyang Lake, by comprehensively assessing the abundance, distribution, size, shape, polymer composition, and micro-morphology of MPs in water and sediment, covering a large geographic area of the Lake and its five main river tributaries. High levels of MPs were detected in water (up to 1064 ± 90 MP/m3) and sediment (up to 1936 ± 121 MP/kg), with the highest concentrations in the Gan River and the lowest in the national Nature Reserves. While a positive correlation was identified between MP abundance in water and sediment, the size distribution of MPs in between water and sediment was distinct. The dominant MP form in sediment and water was fragment and fiber, respectively. Infrared spectroscopy analysis confirmed the dominant polymer types including polypropylene, polyvinyl chloride, polyethylene, polystyrene, and polyvinyl alcohol. Moreover, both µ-FTIR and SEM results suggested significant features of weathering and fragmentation of MPs. This study provides comprehensive data to understand the environmental behavior and pollution magnitude of MPs in China's largest freshwater lake and highlights the significant contribution of smaller-size fractions (0.03-0.1 mm) to improve future MP studies in freshwater systems.


Assuntos
Lagos/análise , Microplásticos/análise , Poluentes Químicos da Água/análise , China , Monitoramento Ambiental/métodos , Sedimentos Geológicos/análise , Microplásticos/química , Microscopia Eletrônica de Varredura , Polietileno/análise , Polietileno/química , Polipropilenos/análise , Polipropilenos/química , Rios/química , Espectroscopia de Infravermelho com Transformada de Fourier
8.
Chemosphere ; 254: 126766, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32957264

RESUMO

Co-pyrolysis of brominated flame retardants (BFRs) with polymeric materials prevails in scenarios pertinent to thermal recycling of bromine-laden objects; most notably the non-metallic fraction in e-waste. Hydro-dehalogenation of aromatic compounds in a hydrogen-donating medium constitutes a key step in refining pyrolysis oil of BFRs. Chemical reactions underpinning this process are poorly understood. Herein, we utilize accurate density functional theory (DFT) calculations to report thermo-kinetic parameters for the reaction of solid polyethylene, PE, (as a surrogate model for aliphatic polymers) with prime products sourced from thermal decomposition of BFRs, namely, HBr, bromophenols; benzene, and phenyl radical. Facile abstraction of an ethylenic H by Br atoms is expected to contribute to the formation of abundant HBr concentrations in practical systems. Likewise, a relatively low energy barrier for aromatic Br atom abstraction from a 2-bromophenol molecule by an alkyl radical site, concurs with the reported noticeable hydro-debromination capacity of PE. Pathways entailing a PE-induced bromination of a phenoxy radical should be hindered in view of high energy barrier for a Br transfer into the para position of the phenoxy radical. Adsorption of a phenoxy radical onto a Cu(Br) site substituted at the PE chain affords the commonly discussed PBDD/Fs precursor of a surface-bounded bromophenolate adduct. Such scenario arises due to the heterogeneous integration of metals into the bromine-rich carbon matrix in primitive recycling of e-waste and their open burning.


Assuntos
Retardadores de Chama/análise , Polietileno/química , Bromo , Halogenação , Hidrocarbonetos Bromados/análise , Cinética , Fenóis , Pirólise , Reciclagem
9.
PLoS One ; 15(8): e0236406, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32745098

RESUMO

To address concerns over plastics in the global environment, this project produced three wood plastics composites (WPCs) which could divert plastics from the waste stream into new materials. The three materials made had a ratio of 85%:15%, 90%:10%, and 95%:5% low density polyethylene (LDPE) to wood powder and were produced using the dissolution method. Physical and mechanical properties of each WPC were evaluated according to Japanese Industrial Standard (JIS) A 5908:2003. Their degradation in nature was evaluated through a graveyard test and assay test conducted in Coptotermes curvignathus termites. Results showed that density, moisture content, thickness swelling and water absorption of the WPCs fulfilled the JIS standard. The mechanical properties of these composites also met the JIS standard, particularly their modulus of elasticity (MOE). Modulus of rupture (MOR) and internal bonding (IB) showed in lower values, depending on the proportion of wood filler they contained. Discoloration of the WPCs was observed after burial in the soil with spectra alteration of attenuated transmission reflectance (ATR) in the band of 500-1000 cm-1 which could be assigned to detach the interphase between wood and plastics. As termite bait, the WPCs decreased in weight, even though the mass loss was comparatively small. Micro Confocal Raman Imaging Spectrometer revealed that termite guts from insects feeding on WPCs contained small amounts of LDPE. This indicated termite can consume plastics in the form of WPCs. Thus WPCs made predominantly of plastics can be degraded in nature. While producing WPCs can assist in decreasing plastics litter in the environment, the eventual fate of the LDPE in termites is still unknown.


Assuntos
Plásticos Biodegradáveis/química , Elasticidade , Polietileno/química , Madeira/química , Plásticos Biodegradáveis/síntese química , Humanos , Polietileno/síntese química , Reciclagem , Água/química
10.
PLoS One ; 15(7): e0236276, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32730348

RESUMO

Red turpentine beetle, Dendroctonus valens (Coleoptera: Curculionidae: Scolytinae) is a non-aggressive pine bark beetle native to North America, and more aggressive invader in China. Dispersing pioneer beetles are attracted to potential host trees by oleoresin monoterpene kairomones, but respond more strongly to those combined with ethanol, a mixture often released from stressed, dying, or recently dead trees. (+)-3-Carene, usually the dominant or co-dominant monoterpene in ponderosa pine, Pinus ponderosa, is a stronger attractant than α-pinene or ß-pinene where tested over a large portion of the D. valens range, while (+)-3-carene+ethanol was shown previously to attract twice the beetles of (+)-3-carene. A field test comparing D. valens attraction among the three monoterpenes when all are released with ethanol has never been reported, and was our objective. In three US Pacific Northwestern pine forests, (-)-ß-pinene+ethanol lures attracted 1.4 to 1.9 times more beetles than (+)-3-carene+ethanol. (+)- or (±)-α-pinene+ethanol lures were least attractive. A 1:1:1 monoterpene mixture+ethanol lure attracted more beetles than the 1:1:1 lure, but it was not statistically higher. Monoterpenes were dispensed from low density polyethylene bottles and their release rates monitored in laboratory and field tests. Under laboratory conditions (+)-3-carene was released much more rapidly than (+)-α-pinene or (-)-ß-pinene when dispensed separately, or in a 1:1:1 mixture. (+)-3-Carene in the 1:1:1 mixture increased the release of both pinenes over their rates when dispensed separately. (-)-ß-Pinene+ethanol is currently the strongest kairomone lure for D. valens attraction in US northwest pine forests, and has value for beetle detection, monitoring, research, and management.


Assuntos
Monoterpenos Bicíclicos/farmacologia , Besouros/fisiologia , Etanol/farmacologia , Florestas , Terebintina/farmacologia , Animais , Monoterpenos Bicíclicos/química , Besouros/efeitos dos fármacos , Geografia , Laboratórios , Noroeste dos Estados Unidos , Polietileno/química , Temperatura , Volatilização
11.
Chemosphere ; 260: 127589, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-32682135

RESUMO

Although recycled plastics provide a low-cost and environmentally friendly alternative for many applications, their desirability is significantly limited by the presence of unpleasant odors from volatile organic compounds (VOCs). In this work, a headspace solid-phase microextraction (HS-SPME) coupled with gas chromatography-mass spectrometry (GC-MS) method was optimized to analyze volatile compounds from an odorous recycled plastic resin which was roughly composed of 85-90% polypropylene (PP) and 15-10% high-density polyethylene (HDPE). A large variety of aliphatic hydrocarbons and 13 additive residues were detected. Statistical tools were employed to screen the VOCs and successfully identified three components, i.e., 2,4-dimethyl-heptane, 4-methyl-octane and octamethylcyclotetrasiloxane (D4), which were significantly related to the odor intensity of the recycled plastic resin (p-values < 0.05). 2,4-Dimethyl-heptane has a strong, pungent plastic smell, which is very similar to the odor of the recycled resin. It is identified as a major source of the odor. Past relevant research has not been able to establish a direct link between an odorous compound and the undesirable odor of recycled plastic until now. 4-Methyl-octane was highly corelated to 2,4-dimethyl-heptane and somewhat contributed to the odor. D4 does not have an odor, but it may serve as an indicator of some odorous residues from personal care products.


Assuntos
Odorantes/análise , Resinas Sintéticas/química , Microextração em Fase Sólida/métodos , Compostos Orgânicos Voláteis/análise , Cromatografia Gasosa-Espectrometria de Massas/métodos , Plásticos/química , Polietileno/química , Polipropilenos/química , Reciclagem
12.
PLoS One ; 15(7): e0232745, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32609722

RESUMO

Microplastics or plastic particles less than 5 mm in size are a ubiquitous and damaging pollutant in the marine environment. However, the interactions between these plastic particles and marine microorganisms are just starting to be understood. The objective of this study was to measure the responses of a characteristic marine organism (Synechococcus sp. PCC 7002) to an anthropogenic stressor (polyethelene nanoparticles and microparticles) using molecular techniques. This investigation showed that polyethylene microparticles and nanoparticles have genetic, enzymatic and morphological effects on Synechococcus sp. PCC 7002. An RT-PCR analysis showed increases in the expression of esterase and hydrolase genes at 5 days of exposure to polyethylene nanoparticles and at 10 days of exposure to polyethylene microparticles. A qualitative enzymatic assay also showed esterase activity in nanoparticle exposed samples. Cryo-scanning electron microscopy was used to assess morphological changes in exopolymer formation resulting from exposure to polyethylene microparticles and nanoparticles. The data from this paper suggests that microplastic and nanoplastics could be key microbial stressors and should be investigated in further detail.


Assuntos
Microplásticos/toxicidade , Nanopartículas/toxicidade , Polietileno/química , Polietileno/toxicidade , Estresse Fisiológico/efeitos dos fármacos , Synechococcus/efeitos dos fármacos , Synechococcus/fisiologia , Biofilmes/efeitos dos fármacos , Atividades Humanas , Microplásticos/química , Nanopartículas/química , Tamanho da Partícula , Synechococcus/citologia , Synechococcus/genética , Poluentes Químicos da Água/química , Poluentes Químicos da Água/toxicidade
13.
AAPS PharmSciTech ; 21(5): 199, 2020 Jul 16.
Artigo em Inglês | MEDLINE | ID: mdl-32676796

RESUMO

A new transdermal drug delivery system of nanofiber membrane with good biocompatibility and high drug loading was developed by electrospinning technology in this study. Using vinyl alcohol-co-ethylene (PVA-co-PE) polymer as a spinning matrix and non-steroidal anti-inflammatory drug (NSAID) sulindac (SUL) as a model drug, the SUL@PVA-co-PE nanofiber membrane was prepared and characterized systematically. The morphology, molecular vibrational transitions, thermogravimetric attributes, and in vitro drug release and transdermal characteristics of drug-loaded nanofiber membranes were analyzed. The results indicated that the surface of PVA-co-PE nanofibers was uniform and smooth with the diameter ranged from 461 to 696 nm. Notably in vitro simulation experiments demonstrated that SUL@PVA-co-PE nanofiber membrane could provide a continuous drug release to reach the effective concentration of the drug, and exhibited significantly higher cumulative drug permeability compared to commercially available patches, Taken together, PVA-co-PE nanofiber membranes exhibited the characteristics of high drug loading and stability, and represented the potential to be utilized as a new transdermal drug delivery carrier with pronounced development prospect.


Assuntos
Membranas Artificiais , Nanofibras , Polietileno/química , Álcool de Polivinil/química , Administração Cutânea , Animais , Anti-Inflamatórios não Esteroides/administração & dosagem , Portadores de Fármacos , Masculino , Camundongos , Camundongos Endogâmicos ICR , Permeabilidade , Sulindaco/administração & dosagem
14.
J Chromatogr A ; 1625: 461340, 2020 Aug 16.
Artigo em Inglês | MEDLINE | ID: mdl-32709363

RESUMO

In this study, a magnetized polyethylene composite has been prepared using ball milling procedure and employed as an efficient sorbent in magnetic dispersive solid phase extraction combined with dispersive liquid-liquid microextraction. This method has been utilized for the extraction and preconcentration of some pesticides from fruit juices prior to their quantification by gas chromatography-flame ionization detection. The prepared sorbent consisted of the natural iron oxide (obtained from sand) coated with polyethylene. In the present work, first a few mg of the magnetic composite is added into an aqueous solution containing the analytes and vortexed. After that the analytes are eluted with iso-propanol from the surface of the composite particles separated in the presence of a strong external magnetic field. For further enrichment of the analytes, 1,2-dibromoethane (at µL-level) as an extraction solvent is mixed with the obtained eluent and hastily injected into deionized water. The composite was characterized using techniques including vibrating sample magnetometry, X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy, Brunauer-Emmett-Teller nitrogen sorption, and Fourier transform infrared spectrophotometry. Under optimal conditions, the method provided low limits of detection (0.94-1.9 µg L-1) and quantification (3.2-5.9 µg L-1), high enrichment factors (570-692), good linearity (r2 ≥ 0.994), and satisfactory repeatabilities (relative standard deviations ≤ 8% for intra- and inter-day precisions at a concentration of 15 µg L-1 of each analyte).


Assuntos
Fenômenos Magnéticos , Praguicidas/isolamento & purificação , Polietileno/química , Polietileno/síntese química , Adsorção , Centrifugação , Cromatografia Gasosa , Sucos de Frutas e Vegetais/análise , Concentração de Íons de Hidrogênio , Limite de Detecção , Microextração em Fase Líquida , Concentração Osmolar , Praguicidas/análise , Praguicidas/química , Reprodutibilidade dos Testes , Extração em Fase Sólida , Solventes/química , Espectroscopia de Infravermelho com Transformada de Fourier , Fatores de Tempo , Difração de Raios X
15.
Food Chem ; 331: 127323, 2020 Nov 30.
Artigo em Inglês | MEDLINE | ID: mdl-32554310

RESUMO

Beverages, often packaged in plastic, can be a source of microplastics in the human diet. In this study, an improved method for detection of microplastics in white wines capped with synthetic stoppers is explored. Visual quantification in the stereomicroscope or using Nile Red were excluded due to the small size of particles. Quantification in the optical microscope identified up to 5,857 particles.L-1 but lacked chemical characterization. Finally, micro-Raman spectroscopy was used for the first time in complex beverages in the identification of microplastics particles in white wines, allowing identification of at least one synthetic particle for each bottle, except in two cases. Improvements included reduction in volume filtered, selection of aluminum oxide filters, selection of blue laser and lack of H2O2 treatment. Using this method, identification of all particles present in small representative areas of the filter by micro-Raman spectroscopy will allow proper quantification of microplastics in complex beverage matrices.


Assuntos
Microplásticos/análise , Microplásticos/química , Polietileno/química , Análise Espectral Raman , Poluentes Químicos da Água/análise , Poluentes Químicos da Água/química , Vinho/análise , Monitoramento Ambiental , Humanos , Peróxido de Hidrogênio/química , Oxazinas/química
16.
Ecotoxicol Environ Saf ; 201: 110860, 2020 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-32563162

RESUMO

The biodegradation of naphthalene using low-density polyethylene (LDPE) immobilized Exiguobacterium sp. RKS3 (MG696729) in a packed bed bioreactor (PBBR) was studied. The performance of a continuous PBBR was evaluated at different inlet flow rates (IFRs) (20-100 mL/h) under 64 days of operation. The maximum naphthalene removal efficiency (RE) was found at low IFR, and it further decreased with increasing IFRs. In a continuous PBBR, the external mass transfer (EMT) aspect was analysed at various IFRs, and experimental data were interrelated between Colburn factor (JD) and Reynolds number (NRe) as [Formula: see text] . A new correlation [Formula: see text] was obtained to predict the EMT aspect of naphthalene biodegradation. Andrew-Haldane model was used to evaluate the bio-kinetic parameters of naphthalene degradation, and kinetic constant νmax, Js, and Ji were found as 0.386 per day, 13.6 mg/L, and 20.54 mg/L, respectively.


Assuntos
Reatores Biológicos/microbiologia , Naftalenos/análise , Poluentes Químicos da Água/análise , Purificação da Água/métodos , Bacillales/crescimento & desenvolvimento , Bacillales/metabolismo , Biodegradação Ambiental , Células Imobilizadas/microbiologia , Cinética , Polietileno/química
17.
Chemosphere ; 257: 127225, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32505036

RESUMO

The role of plastic as a vector for bioaccumulation of hydrophobic organic pollutants has been widely studied. However, the interactions between microplastics (MPs) and crude oil, and the transfer kinetics of sorbed oil from ingested MPs into aquatic biota are largely unknown. In this study, interactions between MPs and crude oil in seawater and digestive tract mimic of aquatic biota have been examined. To mimic the living, transportation and cooking conditions of aquatic organisms, sorption and desorption behaviors were investigated under room temperature-bath (25 °C), ice-bath (0∼4 °C) and boiling water-bath (95∼100 °C), and pH was set as 4 and 7 for the simulated gut fluid. The results showed that sorption capacity of polyethylene (PE) MPs for crude oil in seawater was higher than that in intestinal tract, indicating more oil residue in aqueous phase of gut fluid in the present of organic particles. The sorption kinetics models were well fitted to the pseudo-order model, and isotherms models were well fitted to the Freundlich model. In addition, the results demonstrated that temperature played a significant effect on crude oil viscosity, and the sorption capacity under different temperatures was in the order of 25 °C > 95∼100 °C > 0∼4 °C, indicating that more oil was remained in aqueous phase at boiling water-bath and ice-bath. The increment of pH enhances the sorption capacities of PE MPs. Moreover, the desorption experiment has supplemented the current findings from the sorption experiments.


Assuntos
Microplásticos/química , Petróleo , Polietileno/química , Poluentes Químicos da Água/química , Adsorção , Organismos Aquáticos , Interações Hidrofóbicas e Hidrofílicas , Cinética , Plásticos/química , Água do Mar/química , Poluentes Químicos da Água/análise
18.
J Food Sci ; 85(7): 2105-2113, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32506566

RESUMO

As a kind of polymer material additive, phthalic acid esters (PAEs) are widely used in food industry. However, PAEs are environmental endocrine disruptors with reproductive toxicity and teratogenic carcinogenicity, which are difficult to be degraded in the natural environment. In this paper, gas chromatography-mass spectrometer (GC-MS) methods for PAEs in polyethylene wrap film were optimized. For diisobutyl phthalate (DIBP) and dibutyl phthalate (DBP) that were mainly detected, the method had a good linearity in 1 to 500 ng/g. Then, we confirmed that the migration of DIBP and DBP from polyethylene wrap film increased with time and temperature. It is found that the migration law in different food simulations well followed the migration dynamics first-level model. The rate constant K1 and initial release rate V0 are inversely proportional to the polarity of the simulated liquid. We hope that this study can serve as a valuable reference for further research on the migration of food packing materials. PRACTICAL APPLICATION: In this paper, we present a simple example of applying migration model to evaluate the migration behaviors of PAEs in food packaging materials along with their hazardous properties. It can serve as a valuable reference for further research on the migration of food packing materials.


Assuntos
Embalagem de Alimentos/instrumentação , Ácidos Ftálicos/química , Polietileno/química , Dibutilftalato/análogos & derivados , Dibutilftalato/química , Cromatografia Gasosa-Espectrometria de Massas/métodos , Polímeros/química
19.
Food Chem ; 329: 126989, 2020 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-32502742

RESUMO

In this study, a polyethylene (PE) film coated with chitosan (CS) and gallic acid (GA) was prepared using plasma modification technology and applied for the preservation of tilapia fillets. Based on the analysis of surface morphology and surface functional groups, it was shown that plasma modification allowed CS and GA coating on PE. And GACS/PE demonstrated better antioxidant ability than CS/PE and GA/PE individually. The results of the tilapia freshness test showed that the total plate count showed that GACS/PE can inhibit 1.52 log CFU/g and delay the production of volatile basic nitrogen below 15 mg/100 g after 14 d of storage. Moreover, GA/PE (0.26 mg MDA/kg) and GACS/PE (0.24 mg MDA/kg) showed better thiobarbituric acid inhibitiry effect than control (0.30 mg MDA/kg) on day 14. These results indicate that these packaging films are efficient in extending the shelf life of tilapia fillets.


Assuntos
Quitosana/química , Embalagem de Alimentos/métodos , Conservação de Alimentos/métodos , Ácido Gálico/química , Polietileno/química , Tilápia , Animais
20.
Chemosphere ; 252: 126534, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32224359

RESUMO

Passive sampling techniques have been widely used to determine the dissolved concentration profiles of hydrophobic organic compounds (HOCs) in sediment porewater. However, the effects of having a protection for the passive sampler on profiling HOCs concentrations in sediment porewater, especially in deep sediment, have remained unclear. To address this issue, low density polyethylene passive samplers with and without protectors, which consisted of glass fiber filter and porous stainless steel shield, were simultaneously deployed in sediment of the Dongjiang River, South China. The results showed that the protectors retarded the dissipation of performance reference compounds (PRCs) from the sampler by a factor of 2-9. The protectors seemed to exert a negligible effect on the measured concentrations of PAHs, BDE-47, and BDE-99 in surficial sediment porewater (0-14 cm depth) from both samplers. However, the sediment porewater concentration profiles of PAHs and BDE-47 from the sampler with protectors were in agreement with those normalized by dry weight in deep sediment (16-34 cm depth), indicating that a diffusion layer established by the protectors may minimize the probability of local depletion of the target analytes in deep sediment. In addition, the log Koc values of PAHs, BDE-47, and BDE-99 exhibited a slight increasing trend with sediment depth. This finding suggested that in situ passive sampling techniques could be a feasible tool in determining the site-specific log Koc values of HOCs at different sediment depths.


Assuntos
Poluentes Químicos da Água/análise , China , Difusão , Monitoramento Ambiental/métodos , Sedimentos Geológicos/química , Éteres Difenil Halogenados , Interações Hidrofóbicas e Hidrofílicas , Compostos Orgânicos , Hidrocarbonetos Policíclicos Aromáticos/análise , Polietileno/química , Porosidade , Rios/química
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