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Chemosphere Sep 2023Sorption studies involving microplastics (MPs) are essential to understand the mechanisms implicated in contaminant retention. In this research, a complete study of the...
Sorption studies involving microplastics (MPs) are essential to understand the mechanisms implicated in contaminant retention. In this research, a complete study of the sorption behaviour of a hormonal contraceptive -levonorgestrel- in MPs of different composition in two distinct matrices was performed, using high-performance liquid chromatography coupled to a UV detector for the determination of levonorgestrel. Characterization of the studied MPs was achieved by X-ray diffraction, differential scanning calorimetry, and Fourier-transformed infrared spectroscopy. Kinetic and isotherm studies were performed using a batch design under controlled conditions: 500 mg of MPs pellets of 3-5 mm diameter, agitation at 125 rpm, and 30 °C. The comparison of results in ultrapure water and artificial seawater, revealed changes in sorption capacity, and the predominant sorption mechanisms involved. Overall, all studied MPs showed sorption affinity towards levonorgestrel, being low-density polyethylene the one with the highest sorption capacity in ultrapure water and polystyrene in seawater.
Topics: Microplastics; Polystyrenes; Polyethylene; Polypropylenes; Plastics; Levonorgestrel; Water; Water Pollutants, Chemical; Adsorption
PubMed: 37244556
DOI: 10.1016/j.chemosphere.2023.139042 -
The Science of the Total Environment Nov 2023Investigation on the distribution and mechanism of co-pyrolysis products is vital to the directional control and high-value utilization of agriculture solid wastes....
Investigation on the distribution and mechanism of co-pyrolysis products is vital to the directional control and high-value utilization of agriculture solid wastes. Co-pyrolysis, devolatilization, kinetics characteristics, and evolution paths of corn stalk (CS) and low-density-polyethylene (LDPE) were investigated via thermogravimetric experiments. The co-pyrolysis behaviors could be separated into two stages: firstly, the degradation of CS (150- 400 °C); secondly, the degradation of CS (400- 550 °C). The devolatilization index (DI) increased with the addition of LDPE. Furthermore, a combination of devolatilization chemical analysis with product analysis to analyze the intrinsic mechanism during co-pyrolysis. The results indicated that the yield of alkanes and olefin in gas products increased with the addition of LDPE. Additionally, LDPE pyrolysis maybe abstract hydrogen from CS pyrolysis and evolved into hydrogen, methane, and ethylene. Further, the co-pyrolysis kinetic parameters were computed by using model-free isoconversion methods, which showed promotion of CS pyrolysis and the reduced activation energy. All the activation energy were declined, which indicated a "bidirectional positive effect" during co-pyrolysis. The mean activation energy of P-cellulose (P-CE), P-hemicellulose (P-HM), P-lignin (P-LG), and LDPE decreased by 23.49 %, 12.89 %, 15.36 %, and 27.82 %, respectively. This study further proves the hydrogen donor transfer pathway in the co-pyrolysis process of CS and LDPE, providing theoretical support for the resource utilization of agricultural solid waste.
Topics: Polyethylene; Biomass; Pyrolysis; Kinetics; Cellulose; Solid Waste
PubMed: 37442473
DOI: 10.1016/j.scitotenv.2023.165443 -
Environmental Science and Pollution... Dec 2023This study investigated the photodegradation of microplastics (MPs) by α-FeO/g-CN. The effects of α-FeO/g-CN on MPs' surface were investigated through various...
This study investigated the photodegradation of microplastics (MPs) by α-FeO/g-CN. The effects of α-FeO/g-CN on MPs' surface were investigated through various techniques. With the addition of α-FeO/g-CN and under visible light irradiation, cracks and folds were observed on the MP films and particles. Compared to the treatment without photocatalyst addition, the mass loss of MPs increased with irradiation time when α-FeO/g-CN was added. Specifically, polystyrene films and particles in water showed 9.94% and 7.81% increased mass loss, respectively. The degradation of MPs using α-FeO/g-CN demonstrated the behavior consistent with the pseudo-first-order kinetic model. The presence of α-FeO/g-CN led to an increase in surface oxygen-containing functional groups and crystallinity while decreasing the average molecular weight of MPs. After 30 days of irradiation, the characteristic tensile bands of MPs with α-FeO/g-CN significantly increased, and the detection of carboxyl bands indicated the formation of carboxylic acid, ketones, and lactones as degradation products.
Topics: Polyethylene; Polystyrenes; Microplastics; Plastics; Carboxylic Acids
PubMed: 37953423
DOI: 10.1007/s11356-023-31000-x -
Environmental Microbiology Jun 2024Plastic pollution is a vast and increasing problem that has permeated the environment, affecting all aspects of the global food web. Plastics and microplastics have...
Plastic pollution is a vast and increasing problem that has permeated the environment, affecting all aspects of the global food web. Plastics and microplastics have spread to soil, water bodies, and even the atmosphere due to decades of use in a wide range of applications. Plastics include a variety of materials with different properties and chemical characteristics, with polyethylene being a dominant fraction. Polyethylene is also an extremely persistent compound with slow rates of photodegradation or biodegradation. In this study, we developed a method to isolate communities of microbes capable of biodegrading a polyethylene surrogate. This method allows us to study potential polyethylene degradation over much shorter time periods. Using this method, we enriched several communities of microbes that can degrade the polyethylene surrogate within weeks. We also identified specific bacterial strains with a higher propensity to degrade compounds similar to polyethylene. We provide a description of the method, the variability and efficacy of four different communities, and key strains from these communities. This method should serve as a straightforward and adaptable tool for studying polyethylene biodegradation.
Topics: Polyethylene; Biodegradation, Environmental; Bacteria; Microbiota; Soil Microbiology
PubMed: 38843592
DOI: 10.1111/1462-2920.16658 -
The Science of the Total Environment Sep 2024The impact of microplastics and their additives on soil nutrient cycling, particularly through microbial mechanisms, remains underexplored. This study investigated the...
The impact of microplastics and their additives on soil nutrient cycling, particularly through microbial mechanisms, remains underexplored. This study investigated the effects of polyethylene microplastics, polyethylene resin, and plastic additives on soil nitrogen content, physicochemical properties, nitrogen cycling functional genes, microbial composition, and nitrogen transformation rates. Results showed that all amendments increased total nitrogen but decreased dissolved total nitrogen. Polyethylene microplastics and additives increased dissolved organic nitrogen, while polyethylene resin reduced it and exhibited higher microbial biomass. Amendments reduced or did not change inorganic nitrogen levels, with additives showing the lowest values. Polyethylene resin favored microbial nitrogen immobilization, while additives were more inhibitory. Amendment type and content significantly interacted with nitrogen cycling genes and microbial composition. Distinct functional microbial biomarkers and network structures were identified for different amendments. Polyethylene microplastics had higher gross ammonification, nitrification, and immobilization rates, followed by polyethylene resin and additives. Nitrogen transformation was driven by multiple functional genes, with Proteobacteria playing a significant role. Soil physicochemical properties affected nitrogen content through transformation rates, with C/N ratio having an indirect effect and water holding capacity directly impacting it. In summary, plastic additives, compared to polyethylene microplastics and resin, are less conducive to nitrogen degradation and microbial immobilization, exert significant effects on microbial community structure, inhibit transformation rates, and ultimately impact nitrogen cycling.
Topics: Soil Microbiology; Microplastics; Polyethylene; Soil; Nitrogen Cycle; Soil Pollutants; Nitrogen; Microbial Interactions
PubMed: 38851351
DOI: 10.1016/j.scitotenv.2024.173771 -
Journal of Hazardous Materials Oct 2023Polyethylene (PE) is a widely used plastic known for its resistance to biodegradation, posing a significant environmental challenge. Recent advances have shed light on...
Polyethylene (PE) is a widely used plastic known for its resistance to biodegradation, posing a significant environmental challenge. Recent advances have shed light on microorganisms and insects capable of breaking down PE and identified potential PE-degrading enzymes (PEases), hinting at the possibility of PE biorecycling. Research on enzymatic PE degradation is still in its early stages, especially compared to the progress made with polyethylene terephthalate (PET). While PET hydrolases have been extensively studied and engineered for improved performance, even the products of PEases remain mostly undefined. This Perspective analyzes the current state of enzymatic PE degradation research, highlighting obstacles in the search for bona fide PEases and suggesting areas for future exploration. A critical challenge impeding progress in this field stems from the inert nature of the C-C and C-H bonds of PE. Furthermore, breaking down PE into small molecules using only one monofunctional enzyme is theoretically impossible. Overcoming these obstacles requires identifying enzymatic pathways, which can be facilitated using emerging technologies like omics, structure-based design, and computer-assisted engineering of enzymes. Understanding the mechanisms underlying PE enzymatic biodegradation is crucial for research progress and for identifying potential solutions to the global plastic pollution crisis.
Topics: Polyethylene; Polyethylene Terephthalates; Biodegradation, Environmental; Hydrolases
PubMed: 37690195
DOI: 10.1016/j.jhazmat.2023.132449 -
Journal of Hazardous Materials Jul 2023Microplastics (MPs) contamination in soils seriously threatens agroecosystems globally. However, very few studies have been done on the effects of MPs on the soil...
Microplastics (MPs) contamination in soils seriously threatens agroecosystems globally. However, very few studies have been done on the effects of MPs on the soil nitrogen cycle and related functional microorganisms. To assess MP's impact on the soil nitrogen cycle and related functional bacteria, we carried out a one-month soil incubation experiment using typical acidic soil. The soil was amended with alfalfa meal and was spiked with 1% and 5% (mass percentage) of low-density polyethylene (LDPE) and polyvinyl chloride (PVC) MPs. Our results showed that both LDPE and PVC addition significantly increased soil nitrification rate and nitrate reductase activity, which could further promote soil denitrification. The relative abundance of diazotrophs, ammonium oxidizing, and denitrifying bacterial groups were significantly altered with MPs addition. Moreover, the MPs treatments greatly enhanced denitrifying bacteria richness. Redundancy analysis showed that nitrate reductase activity was the most significant factor affecting the soil functional bacterial community. Correlation analysis shows that Nitrosospira genus might be for the improvement of soil nitrification rate. Our results implied that MPs exposure could significantly affect the soil nitrogen cycling in farmland ecosystems by influencing essential nitrogen functional microorganisms and related enzymatic activities.
Topics: Nitrification; Polyethylene; Microplastics; Plastics; Polyvinyl Chloride; Ecosystem; Soil; Nitrogen; Bacteria; Nitrate Reductases; Soil Microbiology
PubMed: 37043864
DOI: 10.1016/j.jhazmat.2023.131391 -
Chemosphere May 2024The environmental presence of nano- and micro-plastic particles (NMPs) is suspected to have a negative impact on human health. Environmental NMPs are difficult to sample...
The environmental presence of nano- and micro-plastic particles (NMPs) is suspected to have a negative impact on human health. Environmental NMPs are difficult to sample and use in life science research, while commercially available plastic particles are too morphologically uniform. Additionally, this NMPs exposure exhibited biological effects, including cell internalization, oxidative stress, inflammation, cellular adaptation, and genotoxicity. Therefore, developing new methods for producing heterogenous NMPs as observed in the environment is important as reference materials for research. Thus, we aimed to generate and characterize NMPs suspensions using a modified ultrasonic protocol and to investigate their biological effects after exposure to different human cell lines. To this end, we produced polyethylene terephthalate (PET) NMPs suspensions and characterized the particles by dynamic light scattering and scanning electron microscopy. Ultrasound treatment induced polymer degradation into smaller and heterogeneous PET NMPs shape fragments with similar surface chemistry before and after treatment. A polydisperse suspension of PET NMPs with 781 nm in average size and negative surface charge was generated. Then, the PET NMPs were cultured with two human cell lines, A549 (lung) and HaCaT (skin), addressing inhalation and topical exposure routes. Both cell lines interacted with and have taken up PET NMPs as quantified via cellular granularity assay. A549 but not HaCaT cell metabolism, viability, and cell death were affected by PET NMPs. In HaCaT keratinocytes, large PET NMPs provoked genotoxic effects. In both cell lines, PET NMPs exposure affected oxidative stress, cytokine release, and cell morphology, independently of concentration, which we could relate mechanistically to Nrf2 and autophagy activation. Collectively, we present a new PET NMP generation model suitable for studying the environmental and biological consequences of exposure to this polymer.
Topics: Humans; Polyethylene Terephthalates; Microplastics; Polymers; Inflammation; Oxidative Stress; Autophagy; Plastics; Polyethylene
PubMed: 38575082
DOI: 10.1016/j.chemosphere.2024.141813 -
The Science of the Total Environment Nov 2023The ubiquity of microplastic is widely recognized as pollution. Microplastic can affect the growth performances of plants. Buckwheat is a potential model crop to...
The ubiquity of microplastic is widely recognized as pollution. Microplastic can affect the growth performances of plants. Buckwheat is a potential model crop to investigate plant responses to hazardous materials. Still, little is known about the response of buckwheat to microplastics. Thus, this study investigated the effect and uptake of polyethylene (PE) in buckwheat plant growth by monitoring the morphological and photosynthetic merits, antioxidant systems and transcriptome analysis of gene expression. Results confirmed that the impacts of PE on buckwheat growth were dose-dependent, while the highest concentration (80 mg/L) exposure elicited significantly negative responses of buckwheat. PE can invade buckwheat roots and locate in the vascular tissues. PE exposure disturbed the processes of carbon fixation and the synthesis of ATP from ADP + Pi in buckwheat leaves. The promotion of photosynthesis under PE exposure could generate extra energy for buckwheat leaves to activate antioxidant systems by increasing the antioxidant enzyme activities at an expense of morphological merits under microplastic stresses. Further in-depth study is warranted about figuring out the interactions between microplastics and biochemical responses (i.e., photosynthesis and antioxidant systems), which have great implications for deciphering the defense mechanism of buckwheat to microplastic stresses.
Topics: Microplastics; Plastics; Polyethylene; Transcriptome; Fagopyrum; Antioxidants; Gene Expression Profiling
PubMed: 37467981
DOI: 10.1016/j.scitotenv.2023.165587 -
Applied and Environmental Microbiology Jul 2023SARS-CoV-2 is primarily a respiratory virus that can potentially be transmitted through fomites. Sodium hypochlorite (NaOCl) and peracetic acid (PAA) are widely used...
SARS-CoV-2 is primarily a respiratory virus that can potentially be transmitted through fomites. Sodium hypochlorite (NaOCl) and peracetic acid (PAA) are widely used disinfectants on surfaces in diverse settings such as hospitals and food production facilities. The objectives of this study were to investigate the virucidal efficacy of NaOCl and PAA against SARS-CoV-2 using the ASTM standard methods. In the suspension assay, NaOCl and PAA (5, 50, and 200 ppm) were tested against SARS-CoV-2 in the presence/absence of soil load after 1 min of contact time. In the carrier assay, NaOCl and PAA were tested at 200, 400, 600, and 1,000 ppm for 1 min and 200 and 1,000 ppm for 5 and 10 min. Stainless steel (SS) and high-density polyethylene (HDPE) disks were used as carriers. The virus was suspended in soil load and the disinfectants were prepared in 300 ppm of hard water. Virus quantification was done by TCID50 assay using Vero-E6 cell line. NaOCl and PAA were effective (> 3 log reduction in infectious virus) at 50 ppm in the absence of soil load. However, in the presence of soil load, 200 ppm was required for > 3 log reduction in virus infectivity. In contrast, NaOCl and PAA at 200 ppm and with a 1-min contact time were not effective against SARS-CoV-2 on either SS or HDPE surfaces. PAA at 200 ppm for 10 min was effective against SARS-CoV-2 on SS and HDPE surfaces, whereas NaOCl required 1,000 ppm for 10 min to be effective against SARS-CoV-2 on both surfaces. In the context of the COVID-19 pandemic, the World Health Organization (WHO) recommended the use of chlorine-based products such as sodium hypochlorite (NaOCl) at 1,000 ppm for a minimum of 1 min to disinfect environmental surfaces. However, this recommendation was not based on validated studies on the actual SARS-CoV-2 itself. In fact, over half of the chemical disinfectants, including many peracetic acid products, listed in EPA List N were approved based on "kills a harder-to-kill pathogen" without further validation on SARS-CoV-2. Research on SARS-CoV-2 is restricted to BSL3 laboratories and the urgency of tackling the pandemic might explain the lack of studies on the actual virus. Our results show that the WHO recommendation of 1 min contact time with 1,000 ppm NaOCl is not effective against SARS-CoV-2 on surfaces. Also, our results indicate that PAA is effective against SARS-CoV-2 on surfaces and can be used as safer and more environmentally friendly alternative to NaOCl at a lower concentration.
Topics: Humans; Sodium Hypochlorite; Peracetic Acid; SARS-CoV-2; Pandemics; Polyethylene; COVID-19; Disinfectants
PubMed: 37347194
DOI: 10.1128/aem.00622-23