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1.
Sci Total Environ ; 729: 138783, 2020 Aug 10.
Artigo em Inglês | MEDLINE | ID: mdl-32498162

RESUMO

Microplastics (MPs) have aroused rising social concerns. Although amounts of surfactants exist in wastewater and are expected to alter the surface properties of MPs significantly as they are designed to be adsorbed by hydrophobic particles. However, rare works have been done on the influence of surfactants on the coagulation removal process of MPs which was thought to be an effective way to remove MPs together with other natural particles, such as clay. We used 3-D fluorescence imaging to track the coagulation removal process of polystyrene MPs. Our results indicate that nonionic surfactant, tween 20 in ppm scale, could inhibit the coagulation removal of polystyrene MPs significantly. Residue MPs in the effluent is proportional with the surfactant concentration and increases up to tens of times, which will lead to a dramatic increase in their potential environmental risks. Apparent size effect exists in the coagulation in which smaller MPs can escape from the coagulation removal more easily. Mechanism study suggests that the steric resistance of the hydrophilic flexible polyethylene glycol (PEG) layer formed by tween 20 adsorbed on MP surface inhibits clay deposition and thus hinders subsequent agglomeration and precipitation. A surfactant stealth effect, which is used in the design of nanomedicine to avoid the human immune recognition and clearance of nano-drugs from blood circulation, also exists in the coagulation removal process of MPs. Our finding not only proves the strong influence of surfactants on MPs but also will stimulate related studies on other latent surfactant effects of MPs.


Assuntos
Microplásticos/química , Fluorescência , Tensoativos , Poluentes Químicos da Água
2.
Sci Total Environ ; 729: 138766, 2020 Aug 10.
Artigo em Inglês | MEDLINE | ID: mdl-32387768

RESUMO

Adsorption of organic pollutants onto microplastics has been reported in prior studies, indicating the potential of these particles to serve as vectors of pollutants. Most prior investigations, however, have been conducted in laboratories under conditions with relatively little environmental relevance. Here we report the results of in-situ experiments to investigate the adsorption of pharmaceuticals (atenolol, sulfamethoxazole, and ibuprofen) on to eight types of test materials (pellets from five types of widely-used polymers, small pieces of straws, fragments of bags, and glass beads for control). Three sample sets survived 28 days of deployment in New York City waterways. Concentrations of each analyte in water samples taken at these sites were also measured. Adsorption coefficients were calculated based on mass and surface area for each type. Mass-based coefficients showed much higher values for straw and bag samples than other types, consistent with their greater surface area to mass ratios. The surface area-based coefficients were similar among the plastic materials tested as well as the glass beads, indicating that surface area is a major determinant of the pharmaceutical adsorption, regardless of material type. Rapid biofouling, which was observed on all samples, appeared to be the predominant factor controlling the sorption capacity of the plastics. Our observations suggest that extensive biofouling and the formation of biofilms in nutrient-enriched waters can significantly impact the adsorption of pharmaceuticals onto plastics.


Assuntos
Microplásticos/química , Adsorção , Cidade de Nova Iorque , Poluentes Químicos da Água
3.
Chemosphere ; 255: 126912, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32408126

RESUMO

Nanoplastics (NPTs) are defined as colloids that originated from the unintentional degradation of plastic debris. To understand the possible risks caused by NPTs, it is crucial to determine how they are transported and where they may finally accumulate. Unfortunately, although most sources of plastic are land-based, risk assessments concerning NPTs in the terrestrial environmental system (soils, aquifers, freshwater sediments, etc.) have been largely lacking compared to studies concerning NPTs in the marine system. Furthermore, an important limitation of environmental fate studies is that the NPT models used are questionable in terms of their environmental representativeness. This study describes the fate of different NPT models in a porous media under unfavorable (repulsive) conditions, according to their physical and chemical properties: average hydrodynamic diameters (200-460 nm), composition (polystyrene with additives or primary polystyrene) and shape (spherical or polymorphic). NPTs that more closely mimic environmental NPTs present an inhomogeneous shape (i.e., deviating from a sphere) and are more deposited in a sand column by an order of magnitude. This deposition was attributed in part to physical retention, as confirmed by the straining that occurred for the larger size fractions. Additionally, different Derjaguin-Landau-Verwey-Overbeek (DLVO) models -the extended DLVO (XDLVO) and a DLVO modified by surface element integration (SEI) method-suggest that the environmentally relevant NPT models may alter its orientation to diminish repulsion from the sand surface and may find enough kinetic energy to deposit in the primary energetic minimum. These results point to the importance of choosing environmentally relevant NPT models.


Assuntos
Microplásticos/química , Modelos Químicos , Coloides , Água Subterrânea , Hidrodinâmica , Modelos Teóricos , Porosidade , Areia
4.
Chemosphere ; 254: 126789, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32335440

RESUMO

The growth of microplastic (MP) pollution is of increasing concern and represents a global challenge. In situ detection of these small particles is difficult because of their sizes, shapes, transparency or translucency, surface texture and ambient conditions. We propose and demonstrate the use of a prototype optical sensor to detect flat, nearly flat, curved and rough MPs prepared from commercial polyethylene terephthalate (PET) plastics and PET bottles in water. The prototype measures the specular reflection of a laser radiation incident on MPs, with a photodiode, and the transmitted laser speckle pattern, with a charge-coupled device (CCD) camera. The presence of the MPs as well as the optical surface roughness are determined from the specular reflection. Additionally, the so-called speckle contrast calculated from the speckle pattern, as a promising tool, is used to rank the rough MPs according to the different average surface roughness, to approximately twice the wavelength of the probing light. The novel application of laser speckle contrast and the optical roughness estimation allows the description of MP surface roughness in water. Moreover, in combination with earlier studies, these results, therefore, pave a way for the complete and a relatively easier description of MPs properties optical and also advances our step towards the development of simple and robust optical monitoring techniques for micro and nanoplastics in open and wastewater.


Assuntos
Monitoramento Ambiental , Microplásticos/análise , Poluentes Químicos da Água/análise , Microplásticos/química , Plásticos , Polietilenotereftalatos , Águas Residuárias/análise , Água , Poluentes Químicos da Água/química
5.
Chemosphere ; 253: 126706, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32289606

RESUMO

The sorption behavior of 2,2',4,4'-tetrabromodiphenyl ether (BDE-47) on aged polystyrene (PS) microplastics via seawater soaking, ultraviolet (UV) irradiation, seawater soaking and UV irradiation together was investigated. The effects of environmental factors including salinity, pH, and dissolved organic matter (DOM) on sorption of BDE-47 by the aged PS microplastics were analyzed. The equilibrium sorption capacity of BDE-47 by virgin PS, aged PS with seawater soaking, aged PS with UV irradiation and aged PS with seawater soaking and UV irradiation was 6.16, 4.96, 3.53, and 3.75 ng/g, respectively. The decrease in sorption capacity was related to the increase of surface crystallinity and the appearance of surface oxygen-containing functional groups. The kinetic and isotherm models suggested that aging did not change the sorption mechanism of BDE-47 on PS microplastics. pH had negligible impacts on BDE-47 sorption by virgin and aged PS. Sorption capacity of BDE-47 on aged PS in water with high salinity was lower than that on virgin PS, and DOM has less effect on the sorption of BDE-47 on aged PS.


Assuntos
Éteres Difenil Halogenados/química , Microplásticos/química , Poliestirenos/química , Adsorção , Éter , Cinética , Plásticos , Polímeros , Salinidade , Água do Mar , Poluentes Químicos da Água/análise
6.
Proc Natl Acad Sci U S A ; 117(18): 9699-9705, 2020 05 05.
Artigo em Inglês | MEDLINE | ID: mdl-32300006

RESUMO

A ubiquitous structural feature in biological systems is texture in extracellular matrix that gains functions when hardened, for example, cell walls, insect scales, and diatom tests. Here, we develop patterned liquid crystal elastomer (LCE) particles by recapitulating the biophysical patterning mechanism that forms pollen grain surfaces. In pollen grains, a phase separation of extracellular material into a pattern of condensed and fluid-like phases induces undulations in the underlying elastic cell membrane to form patterns on the cell surface. In this work, LCE particles with variable surface patterns were created through a phase separation of liquid crystal oligomers (LCOs) droplet coupled to homeotropic anchoring at the droplet interface, analogously to the pollen grain wall formation. Specifically, nematically ordered polydisperse LCOs and isotropic organic solvent (dichloromethane) phase-separate at the surface of oil-in-water droplets, while, different LCO chain lengths segregate to different surface curvatures simultaneously. This phase separation, which creates a distortion in the director field, is in competition with homeotropic anchoring induced by sodium dodecyl sulfate (SDS). By tuning the polymer chemistry of the system, we are able to influence this separation process and tune the types of surface patterns in these pollen-like microparticles. Our study reveals that the energetically favorable biological mechanism can be leveraged to offer simple yet versatile approaches to synthesize microparticles for mechanosensing, tissue engineering, drug delivery, energy storage, and displays.


Assuntos
Elastômeros/química , Cristais Líquidos/química , Microplásticos/química , Pólen/química , Biofísica/métodos , Matriz Extracelular/química , Cloreto de Metileno/química , Dodecilsulfato de Sódio/química , Propriedades de Superfície
7.
Int J Nanomedicine ; 15: 1929-1938, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32256069

RESUMO

Background: Nanoscale surface roughness has been suggested to have antibacterial and antifouling properties. Several existing models have attempted to explain the antibacterial mechanism of nanoscale rough surfaces without direct observation. Here, conventional and liquid-cell TEM are implemented to observe nanoscale bacteria/surface roughness interaction. The visualization of such interactions enables the inference of possible antibacterial mechanisms. Methods and Results: Nanotextures are synthesized on biocompatible polymer microparticles (MPs) via plasma etching. Both conventional and liquid-phase transmission electron microscopy observations suggest that these MPs may cause cell lysis via bacterial binding to a single protrusion of the nanotexture. The bacterium/protrusion interaction locally compromises the cell wall, thus causing bacterial death. This study suggests that local mechanical damage and leakage of the cytosol kill the bacteria first, with subsequent degradation of the cell envelope. Conclusion: Nanoscale surface roughness may act via a penetrative bactericidal mechanism. This insight suggests that future research may focus on optimizing bacterial binding to individual nanoscale projections in addition to stretching bacteria between nanopillars. Further, antibacterial nanotextures may find use in novel applications employing particles in addition to nanotextures on fibers or films.


Assuntos
Antibacterianos/química , Antibacterianos/farmacologia , Membrana Externa Bacteriana/efeitos dos fármacos , Portadores de Fármacos/química , Membrana Externa Bacteriana/ultraestrutura , Portadores de Fármacos/farmacologia , Escherichia coli/efeitos dos fármacos , Microplásticos/química , Microplásticos/farmacologia , Microscopia Eletrônica de Transmissão , Copolímero de Ácido Poliláctico e Ácido Poliglicólico/química , Propriedades de Superfície
8.
Chemosphere ; 253: 126705, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32302904

RESUMO

Polystyrene microplastics (PSMPs) with different sizes, surface charges and aging statuses simulated field PSMPs and were applied to understand their cytotoxicity to Escherichia coli. The PSMPs hardly affected the viability, membrane integrity, ROS generation and ATPase activity of E. coli, and the cytotoxicity of field PSMPs is marginal and assumed to be overestimated. Low concentrations (1.0 mg L-1) of PSMPs dynamically affect the cytotoxicity of Ag+ to E. coli through various toxic mechanisms. PSMPs likely mitigated the cytotoxicity of Ag+ during the initial 24 h of co-exposure by protecting the cell membrane, inhibiting ROS generation and/or recovering ATPase activity (p < 0.05 or p < 0.01). During prolonged co-exposure for 48 h, nonfunctionalized polystyrene (PS-NF) still mitigated the cytotoxicity of Ag+ by protecting the integrity of the cell membrane, and aged PS-NF slightly affected cytotoxicity. PS-NH2 and PS-COOH intensified the cytotoxicity of Ag+ because PS markedly promoted ROS generation and inhibited ATPase activity. Thus, field PSMPs were assumed to exhibit marginal cytotoxicity to E. coli and can combine with surrounding Ag+ to modify the E. coli population levels and even the structure of aquatic ecosystems. Accordingly, the environmental and health risks of field PSMPs require further intensive investigation, and the combined toxicity effects of field PSMPs with Ag+ should be considered carefully due to their dynamic toxic effects and mechanisms.


Assuntos
Microplásticos/toxicidade , Poliestirenos/toxicidade , Prata/toxicidade , Ecossistema , Escherichia coli/efeitos dos fármacos , Íons , Microplásticos/química , Poliestirenos/química , Prata/química
9.
Chemosphere ; 252: 126450, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32222522

RESUMO

Nanoplastics (NPs), which are broken down from large pieces of plastics and caused water environment pollution, are becoming an emerging environmental problem due to their stable structure, high mobility, and easy interactions with ambient organic compounds. Separation of NPs by flocculation may be an effective approach for remediation of NPs contaminated-water. Aluminum ion has been used as a highly efficient flocculant in sewage treatment, and calcium ion also shows excellent sedimentation performance for impurities under high pH conditions. In this study, composite metal calcium-aluminum (Ca/Al) ions were used as flocculants, achieving a settling efficiency of NPs almost as high as 80%. The effects of pH and Ca/Al flocculant ratios on the zeta potentials, solution stability, as well as sedimentation efficiency of NPs were investigated. Results showed that the crystal formation of Ca/Al flocs increased with pH. The contact and adsorption mechanism of NPs by Ca/Al flocs were confirmed by X-ray diffraction, scanning electron microscope, Fourier Transform Infrared Spectrometer, and X-ray photoelectron spectroscopy. The capture of NPs by Ca/Al flocculants could provide a new insight for the treatment of NPs from aqueous environment.


Assuntos
Microplásticos/química , Poluentes Químicos da Água/química , Adsorção , Alumínio/química , Cálcio/química , Floculação , Concentração de Íons de Hidrogênio , Íons , Espectroscopia Fotoeletrônica , Águas Residuárias/química , Água/química , Poluentes Químicos da Água/análise , Difração de Raios X
10.
Ecotoxicol Environ Saf ; 195: 110484, 2020 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-32200150

RESUMO

Microplastics and nonylphenol (NP) are considered as emerging pollutant and have attracted wide attention, while their combined toxicity on aquatic organisms is barely researched. Therefore, the combined toxicity influence of NP with three types of microplastics containing polyethylene (PE1000, 13 µm and PE, 150 µm), polyamide (PA1000, 13 µm and PA, 150 µm) polystyrene (PS, 150 µm) on microalgae Chlorella pyrenoidosa was analyzed. Both growth inhibition, chlorophyll fluorescence, superoxide dismutase (SOD), malondialdehyde (MDA), and catalase (CAT) were determined. We found that single microplastics and NP both inhibited algal growth, thereby causing oxidative stress. The order of inhibition effect in single microplastics experiment was PE1000 > PA1000 > PE ≈ PS > PA. The combined toxicity experiment results indicated that the presence of microplastics had positive effect in terms of alleviating NP toxicity to C. pyrenoidosa, and the microplastics adsorption capacity to NP was the dominant contributing factor for this effect. According to the independent action model, the combined toxicity was antagonistic. Because the negative effect of smaller size microplastics on algal growth was aggravated with prolonged exposure time, the optimum effect of microplastics alleviated NP toxicity was PA1000 at 48 h, while this effect was substituted by PA at 96 h during combined toxicity. Thus, the toxicity of smaller size microplastics has a nonnegligible influence on combined toxicity. This study confirms that microplastics significantly affected the toxicity of organic pollutants on microalgae. Further research on the combined toxicity of smaller size microplastics with pollutants in chronic toxicity is needed.


Assuntos
Chlorella/efeitos dos fármacos , Microplásticos/toxicidade , Fenóis/toxicidade , Poluentes Químicos da Água/toxicidade , Adsorção , Catalase/metabolismo , Chlorella/enzimologia , Chlorella/metabolismo , Interações Medicamentosas , Malondialdeído/metabolismo , Microalgas/efeitos dos fármacos , Microalgas/enzimologia , Microalgas/metabolismo , Microplásticos/química , Estresse Oxidativo , Poliestirenos/toxicidade , Superóxido Dismutase/metabolismo , Poluentes Químicos da Água/química
11.
Chemosphere ; 248: 126064, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32041068

RESUMO

Microplastics (MPs), the appearance of which has gained considerable interest, can act as vectors to transport other pollutants such as metals into organisms. In this study, the sorption isotherms of three model heavy metals (i.e., Cu2+, Cd2+, and Pb2+) on four virgin plastic particles including chlorinated polyethylene (CPE), PVC, and two polyethylene plastic particles (i.e., LPE and HPE). HPE and LPE were investigated. The results showed that MPs can load high amounts of Pb2+, Cu2+ and Cd2+. The sorption affinity of the three metals to the model MPs followed the sequence of CPE > PVC > HPE > LPE. The adsorption process was affected by the chemical structure and electronegativity of the sorbents, and seemed irrelevant to the crystallinity of MPs. For the three metals, Pb2+ exhibited significantly stronger sorption than did Cu2+ and Cd2+ due to the strong electrostatic interaction. Moreover, pH can significantly affect the sorption of metals on MPs, but ionic strength exerted a relatively slight effect on this process. In brief, the electrostatic interaction played an important role in the sorption of Pb2+ to model MPs. For Cd2+ and Cu2+, sorption was determined by electrostatic interaction together with surface complexation onto the plastic surface. This study indicates that depending on the surface physicochemical properties of MPs the adsorption behavior can vary significantly. Therefore, the adsorption process of metals on MPs should be readily affected by other environmental mediums in the environment. The study provides additional insight into the behavior of MPs as a vector of metals.


Assuntos
Metais Pesados/química , Microplásticos/química , Poluentes Químicos da Água/química , Adsorção , Poluentes Ambientais , Concentração Osmolar , Plásticos/química , Polietileno , Propriedades de Superfície , Poluentes Químicos da Água/análise
12.
PLoS One ; 15(2): e0228209, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32012181

RESUMO

Degraded plastic debris has been found in nearly all waters within and nearby urban developments as well as in the open oceans. Natural removal of suspended microplastics (MPs) by deposition is often limited by their excess buoyancy relative to water, but this can change with the attachment of biological matter. The extent to which the attached biological ballast affects MP dynamics is still not well characterised. Here, we experimentally demonstrate using a novel OMCEC (Optical Measurement of CEll colonisation) system that the biological fraction of MP aggregates has substantial control over their size, shape and, most importantly, their settling velocity. Polyurethane MP aggregates made of 80% biological ballast had an average size almost twice of those containing 5% biological ballast, and sank about two times slower. Based on our experiments, we introduce a settling velocity equation that accounts for different biological content as well as the irregular fractal structure of MP aggregates. This equation can capture the settling velocity of both virgin MPs and microbial-associated MP aggregates in our experiment with 7% error and can be used as a preliminary tool to estimate the vertical transport of MP aggregates made of different polymers and types of microbial ballast.


Assuntos
Microplásticos/metabolismo , Microbiologia da Água , Água/química , Algoritmos , Biodegradação Ambiental , Microplásticos/química , Microplásticos/isolamento & purificação , Modelos Teóricos
13.
Chemosphere ; 248: 126071, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32032881

RESUMO

Erosion of microplastics due to residence time in aquatic environments causes roughening of the microplastic. Unfortunately, currently used measurement methods do not provide information on the surface roughness of the microplastic embedded in water. In this study we propose a novel method by using transmittance to get information on the magnitude of the surface roughness of microplastics and to rank microplastics by thickness. For such a purpose, we studied optical properties such as dispersion, absorption of both plastics and water in the partial spectral range of visible light (Vis), transmission and scattering of light by plastic sheets, as well as, the calculated sample thickness in the Vis region. These were explored for the detection of both smooth and roughened plastic sheets immersed in water. Moreover, by using the transmission spectrum and refractive index of both plastic and water it is possible to estimate the average surface roughness of plastic samples. Our results suggest that the optical properties in the Vis region offer an interesting way for the detection of both rough and smooth plastic sheets and for ranking the type of plastics in an aquatic environment.


Assuntos
Monitoramento Ambiental/métodos , Microplásticos/análise , Poluentes Químicos da Água/análise , Microplásticos/química , Refratometria , Propriedades de Superfície , Poluentes Químicos da Água/química
14.
Mar Pollut Bull ; 151: 110797, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-32056592

RESUMO

This study aimed to investigate if microplastics (MPs) type (polyethylene microspheres (mPE), fishing line fibers, film plastic bags MPs and bottle cap particles) and aging affect MPs capacity to sorb Cd or Cu in estuarine salt marsh medium. Tests were carried out in elutriate solution, a simple medium obtained by mixing rhizosediment (sediment in contact with plants roots) with the respective estuarine water, that can be used to simulate water-sediment exchanges in estuarine salt marsh environments. After 7 days of exposure, metals adsorption was only detected for film MPs. No differences were observed between virgin and aged MPs. Salinity also did not influence metal adsorption to mPE. Present results indicate that in estuarine salt marsh areas some types of MPs might adsorb metals, which could affect metals availability.


Assuntos
Cádmio/química , Cobre/química , Microplásticos/química , Poluentes Químicos da Água , Áreas Alagadas , Adsorção , Plásticos
15.
Mar Pollut Bull ; 151: 110868, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-32056648

RESUMO

This study aims to determine the degradation of plastic polypropylene (PP) and identify the presence of microplastic in sediments and seawater along the Tambak Lorok coastal area. The study was conducted by collecting samples from the sea surface area, at 50 cm and 170 cm depths, while seawater and sediments were collected from six stations. The results showed an early stage of degradation because of abiotic factors. The surface morphology of plastic changed, indicating the disorientation of the plastic. Furthermore, the results demonstrated that organic carbon decreased by 3.15%, 6.67%, and 16.76% for the PP applied on surface water, at 50 cm depth and at 170 cm depth, respectively. From six stations, PP microplastic was the dominant type, where microplastic in sediment was bio-fouled fiber ranging in size from 255.23 to 1245.71 µm; however, in seawater, it was 7-111 particles/10 mL and ranged from 270.27 to 1279.12 µm in size.


Assuntos
Monitoramento Ambiental , Plásticos , Polipropilenos/química , Poluentes Químicos da Água/química , Sedimentos Geológicos , Indonésia , Microplásticos/química , Poluentes Químicos da Água/análise
16.
Environ Sci Process Impacts ; 22(2): 398-407, 2020 Feb 26.
Artigo em Inglês | MEDLINE | ID: mdl-31993606

RESUMO

Aquatic plastic debris experiences environmental stressors that lead to breakdown into smaller micro-sized plastic particles. This work quantified microplastic formation with the environmental stressors of UV irradiation followed by mechanical strain induced by movement of water with an emphasis on connecting our results to changes in the materials chemical/physical properties. Polypropylene, polyethylene, and polyethylene terephthalate thin films and polypropylene injection-molded sheets were irradiated with 254 nm UV light, placed into aquatic microcosms, collected through sieving, and counted under a microscope. Results showed increasingly more particles in smaller size classes, the smallest being 74-177 µm. Mechanical strain from the turbulent water caused 2.3-3× more microplastics to be formed for the thinnest (∼25 µm) film and 1.4-2× more for thicker films and sheets. The most common morphology of microplastics was fibers, particularly in thicker polypropylene samples, which was attributed to absorbance of the photons and the changes observed in the crystallinity and glass transition as measured with differential scanning calorimetry (DSC). When irradiated for 24, 48, or 72 h, longer irradiation resulted in more microplastics formed by polypropylene films, which correlated with changes in the glass transition temperature as measured by DSC and the extent of oxidation as measured with FTIR. Irradiation at 300 nm produced fewer microplastics due to slower kinetics of phototransformations. Overall, this work evaluates the impact of combined photodegradation and water motion toward microplastic particles formed. It provides quantitative evidence that mechanical strain of water movement exacerbates photo-induced formation of microplastics and shows that the existence of fibers in natural systems can be the result of photodegradation.


Assuntos
Microplásticos , Poluentes Químicos da Água , Monitoramento Ambiental , Microplásticos/química , Fotólise , Polímeros , Água , Poluentes Químicos da Água/química
17.
Environ Pollut ; 257: 113440, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31706754

RESUMO

More attention was paid to the attachment between microplastics and environmental pollutants. The adsorption performance of Polyethylene (PE) beads (a typical type of microplastics) and Cr(VI) ions with the existence of sodium dodecyl benzene sulfonate (SDBS) was investigated in this paper. The adsorption experiments of Cr(VI) ions by PE microplastics were conducted at different conditions, i.e. PE doses, pH and SDBS concentrations, respectively. The adsorption capability of Cr(VI) ions was increased from 0.39 to 1.36 mg⋅g-1 when the dosage of PE microplastics was increased from 2 to 14 g ⋅L-1 at pH of 5 with addition of SDBS, compared with increasing adsorption capability from 0.03 to 0.32 mg⋅g-1 without addition of SDBS. The pH would influence the adsorption capability with and without the addition of SDBS. When the pH was less than 6, the adsorption capability of Cr(VI) would be promoted by the addition of SDBS; however, there was a contrast tendency when the pH was more than 6, which was attributed to that SDBS would compete with CrO42- for occupying the adsorption sites of PE microplastic. The SDBS concentration would affect the adsorption performance of Cr(VI) ions onto PE microplastics. The peak of the adsorption capacity was at SDBS concentration between 1 and 1.5 mM. This research would provide a basis for investigating the influence of SDBS on adsorption performance of heavy metal by PE microplastics to simulate the surface attachment model of those three kinds of pollutants.


Assuntos
Cromo/química , Microplásticos/química , Poluentes Químicos da Água/química , Adsorção , Benzenossulfonatos , Concentração de Íons de Hidrogênio , Íons , Metais Pesados , Modelos Químicos , Plásticos , Polietileno , Poluentes Químicos da Água/análise
18.
Environ Pollut ; 257: 113475, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31706764

RESUMO

It is of environmental significance to study the leaching performance of additives from microplastics (MPs) and further evaluate the toxicity of leachate to microalgae. Here, we investigated the effects of accelerated aging on characteristics, leaching, and toxicity of commercial lead chromate pigmented MPs. Results show that aging of MPs caused surface cracks and fragmentation, increased their surface area and carbonyl contents, and promoted the release of lead chromate pigment. Chromium (Cr) and lead (Pb) tend to leach under acidic condition, rather than neutral and alkali environment. Aging treatment facilitates the leaching performance and a high concentration of NaCl solution also favors the leaching process. Toxicology experiments demonstrate that only high concentration of leachate (>10 µg L-1) exerted significant inhibitory influence (p < 0.005) on cell photosynthesis of Microcystis aeruginosa. The growth inhibition of algal cells remarkably increased with increasing leachate concentrations. We observed more inhibiting effects on cell growth and photosynthesis using the leachates of aged MPs. Longer aging time leads to more release of Cr and Pb, rendering higher toxicity to microalgae. These novel findings will benefit us from assessing the leaching behavior of additives in MPs and their toxicological risks to aquatic organisms.


Assuntos
Cromatos/química , Chumbo/química , Microplásticos/química , Organismos Aquáticos , Cromatos/toxicidade , Cromo , Chumbo/toxicidade , Microalgas , Microplásticos/toxicidade , Modelos Químicos
19.
Environ Sci Process Impacts ; 22(1): 121-130, 2020 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-31691685

RESUMO

Tire materials are the most commonly found elastomers in the environment and they account for a significant fraction of microplastic pollution. In the discussions on the environmental impact of microplastics tire materials and their sorption properties have been largely overlooked. In this study we used experimental sorption data from six organic probe sorbates sorbing to two tire materials and their major components, styrene butadiene rubber and carbon black, to gain a better understanding of the underlying sorption processes of tire materials. Commonly applied models used to describe non-linear sorption processes were unable to fully explain sorption to tire materials but showed that absorption into the rubber fraction dominated the sorption process. Hydrophobicity was approximated using the hexadecane-water partitioning constant, which correlated very well with the distribution data obtained for styrene rubber, whereas the correlations between hydrophobicity of sorbates and the sorption data to the tire materials were poor. Although hydrophobicity plays an important role in sorption to tire materials, additional interactions must be taken into account. Overall, the processes involved in sorption to tire materials differed significantly from those governing sorption to other microplastics.


Assuntos
Microplásticos , Compostos Orgânicos , Adsorção , Microplásticos/química , Compostos Orgânicos/química , Borracha , Fuligem
20.
Chemosphere ; 242: 125170, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31675574

RESUMO

Microplastics may be present in the environment as primary microplastics (manufactured) or secondary microplastics (result of the continuous degradation of larger plastic pieces into smaller fragments due to environmental, physicochemical and biotic factors). To fully understand the dynamics of microplastic particles and their environmental effects, harmonized, automated, cheap, rapid and reliable methodologies for sampling, extraction and characterization of microplastic need to be developed. This review focuses on the potential of thermal analytical techniques for microplastics characterization and highlights some of the new trends in this area.


Assuntos
Monitoramento Ambiental/métodos , Microplásticos/análise , Termogravimetria , Poluentes Químicos da Água/análise , Cromatografia Gasosa-Espectrometria de Massas , Microplásticos/química , Pirólise , Poluentes Químicos da Água/química
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