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1.
Water Res ; 170: 115290, 2020 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-31770647

RESUMO

Microplastics (MPs) discharged into the natural environment undergo various wearthering pathways, such as mechanical abrasion and ultraviolet (UV) irradiation. However, little is known about the effects of such aged MPs on the bioavailability of hydrophobic organic compounds (HOCs) in aqueous environments. To simulate the natural oxidation and UV-ageing process of MPs, three kinds of modified polyethylene MPs were obtained by plastic etching processes common in industry and UV irradiation, namely, etched MPs (EMPs), UV-aged MPs (UV-MPs), and etched MPs followed by UV ageing (UV-EMPs). The modified MPs showed a higher content of surface oxygen-containing groups than the pristine MPs, and the specific surface area and pore volume increased significantly after etching and ultraviolet ageing, especially for the EMPs (1.67 m2 g-1 and 0.0049 cm³ g-1) and UV-EMPs (2.37 m2 g-1 and 0.0089 cm³ g-1). The effect of modified MPs on the availability of 10 polycyclic aromatic hydrocarbons (PAHs, logKow 4.18-6.20) was evaluated by negligible-depletion solid-phase microextraction (nd-SPME). The free concentrations (Cfree) of most PAHs (except for less hydrophobic PAHs, logKow 4.18 and 4.56) decreased with an increasing concentration of MPs. The logarithms of the sorption coefficients of PAHs with various MPs (logKMPs, logKUV-MPs, logKEMPs and logKUV-EMPs) were linearly correlated with logKow, suggesting that the sorption is hydrophobicity dependent. Compared with the results for pristine MPs (logKMP 3.80-4.95), UV ageing only slightly enhanced the sorption of PAHs by MPs (logKUV-MPs 3.71-4.98), whereas the plastic etching processes significantly enhanced sorption (logKEMPs 3.85-5.18 and logKUV-EMPs 3.90-5.28). The sorption of PAHs to MPs is mainly based on partitioning; however, a mechanism of adsorption also likely takes place in EMPs and UV-EMPs due to hydrogen bonding and π-π interactions. Desorption study indicated that PAH desorption from MPs are dominated by film diffusion. However, intraparticle diffusion also takes great part for the EMPs. These results suggest that modification of MPs in the natural environment will change the availability of HOCs.


Assuntos
Hidrocarbonetos Policíclicos Aromáticos , Poluentes Químicos da Água , Adsorção , Plásticos
2.
Waste Manag ; 102: 561-568, 2020 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-31770690

RESUMO

Catalytic fast co-pyrolysis of waste greenhouse plastic films and rice husk over a hierarchical HZSM-5/MCM-41 catalyst was performed in an analytical Py-GC/MS. We evaluated the effect of pyrolysis temperature and the ratio of rice husk to waste greenhouse plastic films on the total peak area of condensable organic products and CO2. In order to evaluate synergy possibilities among the two feedstocks, we performed non-catalytic pyrolysis and catalytic fast pyrolysis of rice husk and waste greenhouse plastic films separately. In addition, we report results for the catalytic fast co-pyrolysis of the mixture rice husk and waste greenhouse plastic films. The maximum relative content of hydrocarbons from catalytic fast co-pyrolysis of rice husk and waste greenhouse plastic films is obtained at 600 °C. When the mass ratio of rice husk to waste greenhouse plastic films is 1:1.5, the relative content of hydrocarbons reaches a maximum (71.1%). The hierarchical micro-mesoporous composite molecular sieve used in this work has outstanding catalytic activity and increases the relative content of hydrocarbons.


Assuntos
Oryza , Biocombustíveis , Catálise , Cromatografia Gasosa-Espectrometria de Massas , Temperatura Alta , Plásticos , Pirólise
3.
Bioresour Technol ; 297: 122411, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31767431

RESUMO

Sulfonated activated carbon-based catalysts were prepared by microwaved-assisted carbonization of phosphoric acid activated corncob followed by sulfonation using concentrated sulfuric acid. Sulfonation at different temperatures and times resulted in varied SO3H group density of the SAC catalysts. Sulfonation temperature showed a significant effect on the introduction of SO3H on the AC precursor while time had minor role. The SAC catalysts were characterized by means of N2 sorption analysis (specific surface area, pore-volume, average pore width), FTIR spectroscopy, SEM imaging, and sulfur analysis. The impact of catalysts SO3H density on the product distribution and bio-oil composition from the catalytic co-pyrolysis of Douglas fir and LDPE was evaluated. The highest bio-jet fuels (aromatics and C9-16 alkanes) obtained was 97.51% using the SAC catalyst sulfonated at 100 °C for 5 h. Results showed that SAC has great potential as catalyst in the co-pyrolysis of biomass and plastics for the production of jet-fuel range hydrocarbons.


Assuntos
Carvão Vegetal , Plásticos , Biocombustíveis , Biomassa , Catálise , Temperatura Alta , Hidrocarbonetos
4.
Bioresour Technol ; 298: 122393, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31757612

RESUMO

The plastics market is dominated by fossil-based polymers, but their gradual replacement by bioplastics (e.g., polyhydroxyalkanoates) is occurring. However, recycling strategies need to be developed to truly unveil the impact of bioplastics on waste accumulation. This review provides a state of the art of recycling strategies investigated for polyhydroxyalkanoate-based polymers and proposes future research avenues. Research on mechanical and chemical recycling is dominated by the use of extrusion and pyrolysis, respectively, while that on biodegradation of polyhydroxyalkanoates is related to soil and aquatic samples, and to anaerobic digestion towards biogas production. Research gaps exist in the relationships between polymer composition and ease of use of all recycling strategies investigated. This is of utmost importance since it will influence the need for separation at the source. Therefore, research emphasis needs to be given to the area to follow the continuous improvement of the process economics towards widespread commercial production of polyhydroxyalkanoates.


Assuntos
Poli-Hidroxialcanoatos , Biodegradação Ambiental , Plásticos , Reciclagem , Solo
5.
Waste Manag ; 102: 804-814, 2020 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-31812094

RESUMO

The single stream recycling (SSR) program is a process in which all recyclable materials are deposited into a single collection bin. SSR has gained popularity in the U.S. due to its inherent abilities in waste collection, and specifically, in Florida, more than twenty counties have recently switched their recycling program from dual stream recycling (DSR) to SSR. Despite a more efficient collection process, mixing all recyclable materials into a single bin can lead to cross contamination even before reaching material recovery facilities (MRFs). This study aims to provide a better understanding of the sorting process and equipment in MRFs, and the impact of the SSR program on contamination rates in outbound materials that were processed through Florida's recycling systems. First, we investigate the audit data obtained from a currently operating MRF in Florida using mass flow analysis to identify the most problematic recyclable streams and the processes with low efficiency and high false separation rates. According to our results, the sorting rates of mixed paper, glass and plastics are under the industry standards. Moreover, we investigate the outbound contamination rates of 35 old corrugated cardboard (OCC) and 266 old newsprints (ONP) samples obtained from four currently operating MRFs in Florida. Based on the results, only 31.4% of OCC samples and none of the ONP samples were within the accepted mills' standards for contamination rates. This study provides valuable insights for lowering contamination and raising the end-product quality by identifying the problematic contaminants and processes in sorting and separation in MRFs.


Assuntos
Eliminação de Resíduos , Florida , Plásticos , Reciclagem
6.
Water Res ; 170: 115358, 2020 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-31816566

RESUMO

Microplastics can be found all over the world, in the remotest regions and even in the Arctic snow. Primary microplastic is either produced as microparticles or enters the natural environment already as microparticles. Whereas secondary microplastic is generated by fragmentation or abrasion of other products in the natural environment. Both pollute the global ecospheres and even enter the human food chain. This study aims at the evaluation of the global publication output on both types of microplastic referring to absolute and contextual numbers. Only since 2006, the focus on the environmental burden led to an enormous increase of publications on MP. While China, USA and Germany are leading players regarding the absolute numbers, Portugal, Chile and Ireland are among the top countries when including socio-economic features and research expenditures. The responsibility for the big plastic waste producers can be shown by significantly correlating numbers of articles and the plastic waste generation, albeit here China and USA fall behind. However, the biggest producers are not the most affected countries. Despite the strong international interest, our study shows that many countries play no role at all in the publication landscape of MP. For future planning, it is necessary to extend the international collaborations to reach sustainable solutions for the whole planet earth.


Assuntos
Plásticos , Poluentes Químicos da Água , China , Monitoramento Ambiental , Alemanha , Humanos , Irlanda , Portugal
7.
Waste Manag ; 102: 351-361, 2020 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-31726315

RESUMO

Mixed, wet, plastic streams containing food waste residues are being increasingly collected at point of use, but are extremely challenging to recycle and are therefore largely sent to landfill. While a challenging waste problem, this also represents an underutilised feedstock, which could be co-processed with biomass, increasing the scope of products, easing out seasonal variation in biomass production and increasing the production capacity of a traditional biorefinery. One promising method of biomass conversion is hydrothermal liquefaction (HTL), where lignocellulosic residues are broken down in water at high temperatures and pressures to produce a bio-crude oil, a solid residue and an aqueous fertiliser. In this study, the co-processing of common plastic waste with pistachio hulls was assessed to investigate the suitability of the HTL approach. The HTL of pistachio hulls was undertaken at 350 °C over 15 and 60 min, with four commonly used plastics: polyethylene, polypropylene, PET and nylon-6, in blends of up to 20 wt% plastic to biomass. A novel FT-IR method was developed to estimate the conversion of plastics in the system, and the product phases were fully analysed. High yields of up to 35% bio-crude were achieved, and under optimal conditions, nylon-6 and PET were found to break down almost completely in the system. PET generated numerous products that distributed predominantly into the aqueous phase; the major decomposition product of nylon-6 was found to be the monomer ∊-caprolactam, also largely partitioning into the aqueous phase. The polyolefins were less reactive; a limited degree of decomposition formed oxidised products, which distributed into the bio-crude phase. This result represents a highly promising method for waste plastic valorisation.


Assuntos
Pistacia , Eliminação de Resíduos , Biocombustíveis , Biomassa , Alimentos , Plásticos , Espectroscopia de Infravermelho com Transformada de Fourier , Temperatura Ambiente , Água
8.
Waste Manag ; 102: 30-39, 2020 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-31655328

RESUMO

The effective utilization of plastic waste, including its use as an energy or chemical resource, has attracted much attention. Nevertheless, energy recovery from plastics via incineration generates air pollutants and toxic compounds, while chemical conversion requires significant energy inputs, especially in the case of gasification. Herein, we report the electrochemical conversion of plastics into electricity or hydrogen without the use of special procedures. When a mixture of plastic solid combined with an acidic solution was fed into an electrochemical cell, the solid was found to dissolve in the solution at 100 °C or higher, followed by the release of protons from the anode to the cathode according to a multi-electron oxidation reaction. This oxidation reaction required an anode that was sufficiently porous so as to allow transport of the reactants. Taking the sponge sample as an example, the dissolved polyurethane had a molecular weight of 2000 or higher, the transport of which was facilitated using a carbon support with a pore diameter of approximately 10 nm. In addition, carbon black having an ordered porous structure exhibited better reagent transport compared to a disordered porous carbon black with similar pore diameters. As a consequence, this cell continuously provided power densities on the order of mW cm-2 in the fuel cell mode and generated hydrogen at a low cell voltage of 0.55 V in the electrolyzer mode, using plastics as fuels at an operational temperature of 200 °C.


Assuntos
Fontes de Energia Bioelétrica , Plásticos , Carbono , Eletricidade , Eletrodos , Incineração
9.
Water Res ; 169: 115270, 2020 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-31731243

RESUMO

Synthetic polymer-based materials are ubiquitous in aquatic environments, where weathering processes lead to their progressive fragmentation and the leaching of additive chemicals. The current study assessed the chemical content of freshwater and marine leachates produced from car tire rubber (CTR), polypropylene (PP), polyethylene terephthalate (PET), polystyrene (PS) and polyvinyl chloride (PVC) microplastics, and their adverse effects on the microalgae Raphidocelis subcapitata (freshwater) and Skeletonema costatum (marine) and the Mediterranean mussel Mytilus galloprovincialis. A combination of non-target and target chemical analysis revealed a number of organic and metal compounds in the leachates, including representing plasticizers, antioxidants, antimicrobials, lubricants, and vulcanizers. CTR and PVC materials and their corresponding leachates had the highest content of tentatively identified organic additives, while PET had the lowest. The metal content varied both between polymer leachates and between freshwater and seawater. Notable additives identified in high concentrations were benzothiazole (CTR), phthalide (PVC), acetophenone (PP), cobalt (CTR, PET), zinc (CTR, PVC), lead (PP) and antimony (PET). All leachates, except PET, inhibited algal growth with EC50 values ranging from 0.5% (CTR) and 64% (PP) of the total leachate concentration. Leachates also affected mussel endpoints, including the lysosomal membrane stability and early stages endpoints as gamete fertilization, embryonic development and larvae motility and survival. Embryonic development was the most sensitive parameter in mussels, with EC50 values ranging from 0.8% (CTR) to 65% (PET) of the total leachate. The lowest impacts were induced on D-shell larvae survival, reflecting their ability to down-regulate motility and filtration in the presence of chemical stressors. This study provides evidence of the relationship between chemical composition and toxicity of plastic/rubber leachates. Consistent with increasing contamination by organic and inorganic additives, the leachates ranged from slightly to highly toxic to mussels and algae, highlighting the need for a better understanding of the overall impact of plastic-associated chemicals on aquatic ecosystems.


Assuntos
Plásticos , Poluentes Químicos da Água , Animais , Organismos Aquáticos , Automóveis , Ecossistema , Borracha
10.
Water Res ; 169: 115284, 2020 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-31739235

RESUMO

As an environmentally friendly material, biochar has been widely used to remediate soil/water contaminants such as heavy metals and organic pollutants. The addition of biochar or modified biochar to porous media might affect the retention of plastic particles and thus influence their fate in natural environment. In this study, both biochar and magnetic biochar (Fe3O4-biochar) were synthesized via a facile precipitation method at room temperature. To determine the significance of biochar and Fe3O4-biochar amendment on the transport and deposition behaviors of plastic particles, the breakthrough curves and retained profiles of three different sized plastic particles (0.02 µm nano-plastic particles, and 0.2 µm and 2 µm micro-plastic particles) in quartz sand were compared with those obtained in quartz sand either with biochar or Fe3O4-biochar amendment in both 5 mM and 25 mM NaCl solutions. The results show that for all three different sized plastic particles under both examined solution conditions, the addition of biochar and Fe3O4-biochar in quartz sand decreases the transport and increases the retention of plastic particles in porous media. Fe3O4-biochar more effectively inhibits the transport of plastic particles than biochar. We found that the addition of biochar/Fe3O4-biochar could change the suspension property and increase the adsorption capacity of porous media (due to the increase of porous media surface roughness and negatively decrease the zeta potentials of porous media), contributing to the enhanced deposition of plastic particles. Moreover, we found that negligible amount of biochar and Fe3O4-biochar (<1%) were released from the columns following the plastic particle transport when the columns were eluted with very low ionic strength solution at high flow rate (to simulate a sudden rainstorm). Similarly, small amount of plastic particles were detached from the porous media under this extreme condition (16.5% for quartz sand, 14.6% for quartz sand with biochar amendment, and 7.5% for quartz sand with Fe3O4-biochar amendment). We found that over 74% of the Fe3O4-biochar can be recovered from the porous media after the retention of plastic particles by using a magnet and 87% plastic particles could be desorbed from Fe3O4-biochar by dispersing the Fe3O4-biochar into 10 mM NaOH solution. In addition, we found that the amendment of unsaturated porous media with biochar/Fe3O4-biochar also decreased the transport of plastic particles. When biochar/Fe3O4-biochar were added into porous media as one layer of permeable barrier near to column inlet, the decreased transport of plastic particles could be also obtained. The results of this study indicate that magnetic biochar can be potentially applied to immobilize plastic particles in terrestrial ecosystems such as in soil or groundwater.


Assuntos
Plásticos , Quartzo , Carvão Vegetal , Ecossistema , Porosidade , Areia , Dióxido de Silício
11.
Water Res ; 170: 115337, 2020 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-31830655

RESUMO

Microplastics are an emerging environmental contaminant. Existing knowledge on the precise transport processes involved in the movement of microplastics in natural water bodies is limited. Microplastic fate-transport models rely on numerical simulations with limited empirical data to support and validate these models. We adopted fluorometric principles to track the movement of both fluorescent dye and florescent stained microplastics (polyethylene) in purpose-built laboratory flumes with standard fibre-optic fluorometers. Neutrally buoyant microplastics behaved in the same manner as a solute (Rhodamine) and more importantly displayed classical fundamental dispersion theory in uniform open channel flow. This suggests Rhodamine, a fluorescent tracer, can be released into the natural environment with the potential to mimic microplastic movement in the water column.


Assuntos
Plásticos , Poluentes Químicos da Água , Monitoramento Ambiental , Polietileno
12.
Int J Phytoremediation ; 22(2): 167-175, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-31468977

RESUMO

Understanding the significance of plant-endophytic bacteria for bisphenol A (BPA) removal is of importance for any application of organic pollutant phytoremediation. In this research, Dracaena sanderiana with endophytic Pantoea dispersa showed higher BPA removal than uninoculated plants at 89.54 ± 0.88% and 79.08 ± 1.20%, respectively. Quantitative Real-Time PCR (qPCR) showed that P. dispersa increased from 3.93 × 107 to 8.80 × 107 16S rRNA gene copy number in root tissues from day 0 to day 5 which indicated that it could assist the plant in removing BPA during the treatment period. pH, chemical oxygen demand (COD), biochemical oxygen demand (BOD), total dissolved solids (TDS), conductivity, and salinity were reduced after 5 days of the experimental period. Particularly, BOD significantly decreased due to activities of the plants and microorganisms. Furthermore, an indigenous bacterial strain, Bacillus cereus NI, from the wastewater could remove BPA in high TDS and alkalinity condition of the wastewater. This work suggests that D. sanderiana plants could be used as a tertiary process in a wastewater treatment system and should be combined with its endophytic bacteria. In addition, B. cereus NI could also be applied for BPA removal from wastewaters with high TDS and salinity.


Assuntos
Dracaena , Águas Residuárias , Bacillus cereus , Compostos Benzidrílicos , Biodegradação Ambiental , Fenóis , Plásticos , RNA Ribossômico 16S
13.
Water Environ Res ; 92(1): 149-156, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31469932

RESUMO

We examined microplastic concentrations, size distributions, and polymer types in surface waters of a northern European dimictic lake. Two sampling methods, a pump sieving water onto filters with different pore sizes (20, 100, and 300 µm) and a common manta trawl (333 µm), were utilized to sample surface water from 12 sites at the vicinity of potential sources for microplastic emissions. The number and polymer types of microplastics in the samples were determined with optical microscopy and µFTIR spectroscopy. The average concentrations were 0.27 ± 0.18 (mean ± SD) microplastics/m3 in manta trawled samples and 1.8 ± 2.3 (>300 µm), 12 ± 17 (100-300 µm) and 155 ± 73 (20-100 µm) microplastics/m3 in pump filtered samples. The majority (64%) of the identified microplastics (n = 168) were fibers, and the rest were fragments. Materials were identified as polymers commonly used in consumer products, such as polyethylene, polypropylene, and polyethylene terephthalate. Microplastic concentrations were high near the discharge pipe of a wastewater treatment plant, harbors, and snow dumping site. PRACTITIONER POINTS: Samples were taken with a manta trawl (333 µm) and a pump filtration system (300/100/20 µm) With pump filtration, small 20-300 µm particles were more common than >300 µm particles The average concentration of manta trawled samples was 0.27 ± 0.18 (mean ± SD) microplastics/m3 FTIR analysis revealed PE, PP, PET, and PAN to be the most common polymers.


Assuntos
Lagos , Poluentes Químicos da Água , Monitoramento Ambiental , Plásticos , Polímeros
14.
Water Res ; 171: 115400, 2020 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-31874389

RESUMO

Human activity is thought to affect the abundance and contamination characteristics of microplastics (MPs) in the environment, which may in turn affect aquatic species. However, few studies have examined the impact of coastal area use pattern on characteristics of MPs in coastal regions. In this study, we investigated MP contamination of abiotic matrices (seawater and sediment) and biotic matrices (bivalves and polychaetes) in three coastal regions characterized by different types of human activity, covering urban, aquafarm, and rural areas. MP abundance was higher in sediment from the urban site than in that from the rural site, but similar to that from the aquafarm site. In the abiotic matrices, different MP polymer compositions were observed among the three sites. Diverse polymers were found in marine matrices from the urban site, implying diverse MP sources in highly populated and industrialized areas. Polystyrene was more abundant in the aquafarm site, reflecting the wide use of expanded polystyrene aquaculture buoys. Polypropylene was more abundant at the rural site, probably due to the use of polypropylene ropes and nets in fishing activity. MP accumulation profiles in marine invertebrates showed trends similar to those exhibited by abiotic matrices, reflecting coastal area use patterns. These results indicate that marine MPs are generated from both land- and marine-based sources, and that the abiotic and biotic marine matrices reflect the MP characteristics.


Assuntos
Plásticos , Poluentes Químicos da Água , Monitoramento Ambiental , Água do Mar
15.
Chemosphere ; 239: 124728, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31499314

RESUMO

Numerous of pollutants threaten our planet, for instance plastic wastes causes a huge potential risk on the environment in addition to many of emergened pollutants as pharmaceutical residue in aquatic environments which affecting ecological balance and in-turn affecting human health. Accordingly, this research proposed an innovative facile, one-step synthesis of functionalized magnetic fullerene nanocomposite (FMFN) via catalytic thermal decomposition of sustainable poly (ethylene terephthalate) bottle wastes as feedstock and ferrocene as a catalyst and precursor of magnetite. Growth mechanism of FMFN was discussed and batch experiments were achieved to examine its adsorption efficiency in relation to Ciprofloxacin antibiotic. Different adsorption parameters including time, initial Ciprofloxacin concentration, and solution temperature were investigated and optimized using Response Surface Methodology (RSM) model. In addition, a study on the antibiotic adsorption process impact on the organisms of an ecosystem was conducted using E. coli DH5α, and results validated method's efficiency in overcoming problem of appearance of antibiotic-resistant microbes.


Assuntos
Ciprofloxacino/isolamento & purificação , Fulerenos/química , Nanocompostos/química , Poluentes Químicos da Água/isolamento & purificação , Adsorção , Ciprofloxacino/química , Ecossistema , Escherichia coli , Concentração de Íons de Hidrogênio , Cinética , Fenômenos Magnéticos , Modelos Estatísticos , Plásticos , Polietilenotereftalatos/química , Tomografia por Emissão de Pósitrons , Reciclagem , Temperatura Ambiente , Poluentes Químicos da Água/química , Purificação da Água/métodos , Purificação da Água/estatística & dados numéricos
16.
Waste Manag ; 102: 909-918, 2020 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-31841983

RESUMO

Ex-situ co-pyrolysis of sugarcane bagasse pith and polyethylene terephthalate (PET) was investigated over zeolite-based catalysts using a tandem micro-reactor at an optimised temperature of 700 °C. A combination of zeolite (HZSM-5) and sodium carbonate/gamma-alumina served as effective catalysts for 18% more oxygen removal than HZSM-5 alone. The combined catalysts led to improved yields of aromatic (8.7%) and olefinic (6.9%) compounds. Carbon yields of 20.3% total aromatics, 18.3% BTXE (benzene, toluene, xylenes and ethylbenzene), 17% olefins, and 7% phenols were achieved under optimal conditions of 700 °C, a pith (biomass) to PET ratio of 4 and an HZSM-5 to sodium carbonate/gamma-alumina ratio of 5. The catalytic presence of sodium prevented coke formation, which has been a major cause of deactivation of zeolite catalysts during co-pyrolysis of biomass and plastics. This finding indicates that the catalyst combination as well as biomass/plastic mixtures used in this work can lead to both high yields of valuable aromatic chemicals and potentially, extended catalyst life time.


Assuntos
Zeolitas , Biomassa , Catálise , Temperatura Alta , Hidrocarbonetos , Plásticos , Pirólise , Sódio
17.
J Sci Food Agric ; 100(2): 540-550, 2020 Jan 30.
Artigo em Inglês | MEDLINE | ID: mdl-31523826

RESUMO

BACKGROUND: Root-shoot ratio plays an important role in mulching effects on increases in maize kernel dry weight and grain yield. RESULTS: We examined the effects of plastic film mulching with fertigation on soil nitrate, soil Olsen-P, aboveground and belowground growth, grain filling, and yield of maize. The 2-year research was conducted in a field with a subsoil sand layer (FSS) and in a field without a subsoil sand layer (FNS) in the Hetao Irrigation District, northwest China. Treatments included two levels of plastic film mulching (FM, fully mulched; PM, partially mulched with a cover ratio of 60%), and a non-mulched (NM) control. Mulching methods significantly increased soil NO3 -N concentrations (SNCs) in the main root zone in FSS, but not in FNS. Mulching significantly increased root length density in the 0-40 cm soil layer. Mulching increased brace roots emergence by 20.2% under full, and by 9.9% under partial mulching, accelerating soil phosphorus use in the surface soil layer. Mulching increased grain yield in spring maize via enhancing base stem diameter, leaf area, and relative chlorophyll content, decreased the ratio of surface root area to leaf area, and improved kernel dry weight increase. CONCLUSIONS: A high proportion of base fertilizer to total fertilizer input resulted in nutrient deficiency during reproductive stage in fertigated maize, therefore, applying a portion of base fertilizer after the maize elongation stage is recommended for a further yield increase of mulched fertigated maize. © 2019 Society of Chemical Industry.


Assuntos
Produção Agrícola/métodos , Raízes de Plantas/crescimento & desenvolvimento , Zea mays/crescimento & desenvolvimento , China , Produção Agrícola/instrumentação , Fertilizantes/análise , Nitratos/análise , Nitratos/metabolismo , Nutrientes/análise , Nutrientes/metabolismo , Raízes de Plantas/metabolismo , Plásticos/análise , Solo/química , Água/análise , Água/metabolismo , Zea mays/metabolismo
18.
J Environ Manage ; 254: 109796, 2020 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-31731026

RESUMO

Plastic films can be considered as a high-value auxiliary material in agriculture with multiple important uses to fulfil, including covering films in greenhouse cultivation system. Such an application enables several benefits and, therefore, it is going through an important upsurge, especially in regions where protected crop cultivation is highly widespread. However, the increased demand for these covering films arouses concerns for their post-use treatment with regard to both the consumption of Non-Renewable Primary Energy (NRPE) resources and the emission of Greenhouse Gases (GHGs). Therefore, environmental analysis is needed to find and follow cleaner paths for the management and treatment of this kind of Agricultural Plastic Waste (APW), especially in the light of the gap currently existing in the specialised literature. In this context, this paper reports upon findings from a combined Life Cycle Assessment (LCA) of single environmental issues (i.e., energy and water consumption, and GHG emissions) applied to a Sicilian firm, representative of APW collection and recycling to obtain Low-Density Polyethylene (LDPE) granules. The results showed that electricity consumption for the whole recycling process is the most NRPE resource demanding and the most GHG emitting input item. Moreover, the washing phase of disused covering films is the highest water demanding within the recycling process. Potential improvements could be achieved by shifting from fossil energy source to renewable one. The installation of a wind power plant would lead to around 56% and 85% reduction in NRPE resource exploitation and GHG emission, respectively. Finally, despite the huge consumption of water and NRPE resources and the resulting GHG emissions, the production of recycled-LDPE granules is far more sustainable than the virgin counterpart.


Assuntos
Plásticos , Reciclagem , Agricultura , Fontes Geradoras de Energia , Efeito Estufa , Centrais Elétricas
19.
Sci Total Environ ; 699: 134366, 2020 Jan 10.
Artigo em Inglês | MEDLINE | ID: mdl-31683209

RESUMO

Studies related to the evaluation of plastics in freshwaters have been increasing in recent years because approximately 80% of plastic items found in the sea are from inland waters. Despite the ecological relevance of these surveys, no information has been available until now about the hazard related to plastic mixtures in freshwaters. To fill this knowledge gap, we carried out a study aimed to assess the environmental risk associated with the "cocktail" of plastics and environmental pollutants adsorbed on their surface in one of the larger European freshwater basins. Plastic debris was collected by a manta trawl along one transect each in four of the Italian subalpine great lakes (Lake Maggiore, Como, Iseo and Garda) and administered to zebra mussels (Dreissena polymorpha), a useful freshwater biological model present in all these lakes. We estimated a plastic density from 4908 MPs/km2 (Lake Iseo) to 272,261 MPs/km2 (Lake Maggiore), while the most common polymers found were polyethylene and polypropylene, with percentages varying between 73% and 100%. A biomarkers suite consisting of 10 different endpoints was performed after 7 days of exposure to investigate the molecular and cellular effects of plastics and related adsorbed pollutants. The main results highlighted a diffuse but different toxicity due to plastics for each lake, and there were significant changes in the antioxidant and detoxifying enzyme activities in Lake Maggiore, Iseo and Garda, an increase in protein carbonylation in L. Como, and a cellular viability decrease of approximately 30% for zebra mussels from L. Iseo and Garda. Despite this variability in the endpoints' responses, the application of the biomarker response index showed a similar environmental hazard due to plastics for all the sampled lakes.


Assuntos
Monitoramento Ambiental , Plásticos/toxicidade , Poluentes Químicos da Água/toxicidade , Animais , Dreissena , Itália , Lagos , Plásticos/análise , Resíduos , Poluentes Químicos da Água/análise
20.
Chemosphere ; 240: 124901, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31563713

RESUMO

Persistent organic pollutants (POPs) released from plastics into water, soil and air are significant environmental and health problem. Continuous exposure of humans to these substances results not only from the slow biodegradation of plastics but also from their ubiquitous use as industrial materials and everyday products. Exposure to POPs may lead to neurodegenerative disorders, induce inflammation, hepatotoxicity, nephrotoxicity, insulin resistance, allergies, metabolic diseases, and carcinogenesis. This has spurred an increasing intense search for natural compounds with protective effects against the harmful components of plastics. In this paper, we discuss the current state of knowledge concerning the protective functions of polyphenols against the toxic effects of POPs: acrylonitrile, polychlorinated biphenyls, dioxins, phthalates and bisphenol A. We review in detail papers from the last two decades, analyzing POPs in terms of their sources of exposure and demonstrate how polyphenols may be used to counteract the harmful environmental effects of POPs. The protective effect of polyphenols results from their impact on the level and activity of the components of the antioxidant system, enzymes involved in the elimination of xenobiotics, and as a consequence - on the level of reactive oxygen species (ROS). Polyphenols present in daily diet may play a protective role against the harmful effects of POPs derived from plastics, and this interaction is related, among others, to the antioxidant properties of these compounds. To our knowledge, this is the first extensive review of in vitro and in vivo studies concerning the molecular mechanisms of interactions between selected environmental toxins and polyphenols.


Assuntos
Poluentes Ambientais/toxicidade , Plásticos/toxicidade , Polifenóis/toxicidade , Compostos Benzidrílicos , Dioxinas , Monitoramento Ambiental/métodos , Poluentes Ambientais/análise , Substâncias Perigosas , Humanos , Doenças Metabólicas/induzido quimicamente , Fenóis , Bifenilos Policlorados/análise , Solo
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