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Traditional plants for plastic separation in homogeneous products employ material physical properties (for instance density). Due to the small intervals of variability of different polymer properties, the output quality may not be adequate. Sensing technologies based on hyperspectral imaging have been introduced in order to classify materials and to increase the quality of recycled products, which have to comply with specific standards determined by industrial applications. This paper presents the results of the characterization of two different plastic polymers—polyethylene terephthalate (PET) and polyvinyl chloride (PVC)—in different phases of their life cycle (primary raw materials, urban and urban-assimilated waste and secondary raw materials) to show the contribution of hyperspectral sensors in the field of material recycling. This is accomplished via near-infrared (900–1700 nm) reflectance spectra extracted from hyperspectral images acquired with a two-linear-spectrometer apparatus. Results have shown that a rapid and reliable identification of PET and PVC can be achieved by using a simple two near-infrared wavelength operator coupled to an analysis of reflectance spectra. This resulted in 100% classification accuracy. A sensor based on this identification method appears suitable and inexpensive to build and provides the necessary speed and performance required by the recycling industry.

Biocatalytic degradation of non-hydrolyzable plastics is a rapidly growing field of research, driven by the global accumulation of waste. Enzymes capable of cleaving the carbon-carbon bonds in synthetic polymers are highly sought-after as they may provide tools for environmentally friendly plastic recycling. Despite some reports of oxidative enzymes acting on non-hydrolyzable plastics, including polyethylene or poly(vinyl chloride), the notion that these materials are susceptible to efficient enzymatic degradation remains controversial, partly driven by a general lack of studies independently reproducing previous observations. Here, we attempt to replicate two recent studies reporting that deconstruction of polyethylene and poly(vinyl chloride) can be achieved using an insect hexamerin from Galleria mellonella (so-called “Ceres”) or a bacterial catalase-peroxidase from Klebsiella sp ., respectively. Reproducing previously described experiments, we do not observe any activity on plastics using multiple reaction conditions and multiple substrate types. Digging deeper into the discrepancies between the previous data and our observations, we show how and why the original experimental results may have been misinterpreted. Recently, two oxidative enzymes have been reported to degrade extremely recalcitrant plastics, PVC and PE. Here, the authors show that these encouraging previous results could not be reproduced, and provide possible reasons for why the data may have been misinterpreted.

Plastic pollution and global warming are widespread issues that lead to several impacts on aquatic organisms. Despite harmful studies on both subjects, there are few studies on how temperature increases plastics’ adverse effects on aquatic animals, mainly freshwater species. So, this study aims to clarify the potential impact of temperature increases on the toxicological properties of polyvinyl chloride nano-plastics (PVC-NPs) in Nile tilapia ( Oreochromis niloticus ) by measuring biochemical and oxidative biomarkers. The fish groups were subjected to three distinct temperatures (30, 32, and 34 °C) and subsequently separated into two groups: 0 and 10 mg/L of PVC-NPs, as it is expected that these temperatures may modify their chemical properties, which can influence their absorption and toxicity in fish. After 4 days, the biochemical response of fish exposed to PVC-NPs and elevated temperatures showed a significant increase in the levels of plasma total proteins, albumin, globulin, aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP), creatinine, and uric acid. Additionally, the level of oxidative stress biomarkers in the liver, gills, and brain was found to have a significant increase in malondialdehyde (MDA) concentration and a decrease in glutathione reduced (GSH) concentration and catalase (CAT) activity in all studied groups. Finally, the current findings revealed a synergistic cytotoxic effect of PVC-NPs and temperatures on the metabolic and oxidative stress indices of O. niloticus .

Microplastics are ubiquitous in estuarine, coastal, and deep sea sediments. The impacts of microplastics on sedimentary microbial ecosystems and biogeochemical carbon and nitrogen cycles, however, have not been well reported. To evaluate if microplastics influence the composition and function of sedimentary microbial communities, we conducted a microcosm experiment using salt marsh sediment amended with polyethylene (PE), polyvinyl chloride (PVC), polyurethane foam (PUF) or polylactic acid (PLA) microplastics. We report that the presence of microplastics alters sediment microbial community composition and nitrogen cycling processes. Compared to control sediments without microplastic, PUF- and PLA-amended sediments promote nitrification and denitrification, while PVC amendment inhibits both processes. These results indicate that nitrogen cycling processes in sediments can be significantly affected by different microplastics, which may serve as organic carbon substrates for microbial communities. Considering this evidence and increasing microplastic pollution, the impact of plastics on global ecosystems and biogeochemical cycling merits critical investigation. Plastic pollution has infiltrated every ecosystem, but few studies have quantified the biogeochemical or ecological effects of plastic. Here the authors show that microplastics in ocean sediment can significantly alter microbial community structure and nitrogen cycling.

On the road to understand the toxicity of nanoplastics, it is important to determine their capacity to interact with other molecules, as this is the first condition that must be met. In particular, polyvinyl chloride (PVC) is a versatile plastic widely used in construction. It can be degraded producing micro and nanoplastics, which can be formed when PVC pipes are cut during the manufacturing of products. PVC is considered to be one of the most toxic plastics, so it is important to analyze potential detrimental effects. This is the main aim of this research. On the basis of Density Functional Theory calculations, we investigated different vinyl chloride oligomers (as models of PVC nanoplastics). Degradation energies, electron donor acceptor capacities to analyze possible oxidation reactions, and interaction energies with different molecules were calculated. The vinyl chloride oligomers used in this investigation are saturated and monounsaturated. This is important since monounsaturated variant is dominant in experimental conditions. We found that none of the oligomers are good electron donors or acceptors. We also investigated different oligomers interacting with ciprofloxacin and •OOH. The interaction energies with ciprofloxacin and •OOH are negative or less than 13 kcal/mol, indicating weak interactions. This theoretical investigation indicates that vinyl chloride oligomers are not expected to be reactive or toxic, considering the electron transfer and the interaction energies with other molecules.

We have created unique near-infrared (NIR)–emitting nanoscale metal-organic frameworks (nano-MOFs) incorporating a high density of Yb 3+ lanthanide cations and sensitizers derived from phenylene. We establish here that these nano-MOFs can be incorporated into living cells for NIR imaging. Specifically, we introduce bulk and nano-Yb-phenylenevinylenedicarboxylate-3 (nano-Yb-PVDC-3), a unique MOF based on a PVDC sensitizer-ligand and Yb 3+ NIR-emitting lanthanide cations. This material has been structurally characterized, its stability in various media has been assessed, and its luminescent properties have been studied. We demonstrate that it is stable in certain specific biological media, does not photobleach, and has an IC 50 of 100 μg/mL, which is sufficient to allow live cell imaging. Confocal microscopy and inductively coupled plasma measurements reveal that nano-Yb-PVDC-3 can be internalized by cells with a cytoplasmic localization. Despite its relatively low quantum yield, nano-Yb-PVDC-3 emits a sufficient number of photons per unit volume to serve as a NIR-emitting reporter for imaging living HeLa and NIH 3T3 cells. NIR microscopy allows for highly efficient discrimination between the nano-MOF emission signal and the cellular autofluorescence arising from biological material. This work represents a demonstration of the possibility of using NIR lanthanide emission for biological imaging applications in living cells with single-photon excitation.

The fabrication of ternary nanocomposites attracts great interest in scientific research worldwide. PVC/PMMA/AgO nanocomposites are prepared by the casting method with various proportions of AgONPs. Analysis of XRD and FTIR spectra exhibited that the structural parameters of PVC/PMMA blend have been affected with increasing nanofiller content. UV–Vis spectra analysis showed that the direct/indirect energy gap are decreased from (5.21/4.92) to (4.86/3.90) eV and the dispersion and oscillation ( E d /E o ) energies are increased from (1.186/4.437) to (73.323/13.638) eV with increasing the content of AgONPs. Linear/nonlinear optical parameters of PVC/PMMA/AgO nanocomposites are enhanced upon increasing AgONPs content. This study also showed that the antibacterial activity of PVC/PMMA/AgO nanocomposites against Gram-positive bacteria ( S. aureus, B. subtilis ) and Gram-negative bacteria ( E. coli) is enhanced. Generally, PVC/PMMA/AgO nanocomposites show promising potential in the field of flexible optoelectronic devices due to the structure-dependent adjustable optical energy gap and in the medical field for their pronounced antibacterial activity.

This study investigated the effect of nanofiller on the structural properties of thermally aged polyvinyl chloride (PVC)/Aluminum oxide (Al2O3) nanocomposites prepared with different amounts of nanoparticles (2.5, 5.0, and 7.5 wt%) using various techniques. Experimental studies were designed to monitor structural changes in PVC/Al2O3 nanocomposites by means of dielectric characterization, charging and discharging currents measurements, SEM and FTIR analyses, and visual observations as a function of nanofiller amount and aging time. The results obtained demonstrated that the dielectric permittivity of PVC was increased for unaged samples with the addition of 2.5% and 7.5% Al2O3 nanoparticles. An increase in dielectric losses is also observed at the same level of filler content, attributable to interfacial polarization driven by improved charge transport and dipole relaxation. A decrease in charging and discharging currents with higher Al2O3 content is attributed to an increase in matrix rigidity, which restricts charge carrier mobility. The charging and discharging currents progressively increased during thermal aging, as polar aging products were formed during this process, which could improve charge mobility and conductivity. FTIR and SEM analyses indicated that with thermal aging, polar groups formation was more likely due to structural decomposition of the matrix and mild dehydrochlorination. The changes in color were indicative of surface degradation. These results provide new insight into the electrical and aging behaviors in PVC/Al2O3 nanocomposites.

Globally, plastics are used in various products. Concerns regarding the human body’s exposure to plastics and environmental pollution have increased with increased plastic use. Microplastics can be detected in the atmosphere, leading to potential human health risks through inhalation; however, the toxic effects of microplastic inhalation are poorly understood. In this study, we examined the pulmonary toxicity of polystyrene (PS), polypropylene (PP), and polyvinyl chloride (PVC) in C57BL/6, BALB/c, and ICR mice strains. Mice were intratracheally instilled with 5 mg/kg of PS, PP, or PVC daily for two weeks. PS stimulation increased inflammatory cells in the bronchoalveolar lavage fluid (BALF) of C57BL/6 and ICR mice. Histopathological analysis of PS-instilled C57BL/6 and PP-instilled ICR mice showed inflammatory cell infiltration. PS increased the NLR family pyrin domain containing 3 (NLRP3) inflammasome components in the lung tissue of C57BL/6 and ICR mice, while PS-instilled BALB/c mice remained unchanged. PS stimulation increased inflammatory cytokines, including IL-1β and IL-6, in BALF of C57BL/6 mice. PP-instilled ICR mice showed increased NLRP3, ASC, and Caspase-1 in the lung tissue compared to the control groups and increased IL-1β levels in BALF. These results could provide baseline data for understanding the pulmonary toxicity of microplastic inhalation.

In this work, novel polymeric blends were prepared from polyvinyl chloride (PVC) and silkworm cocoon waste (SCW), that were defective cocoons excluded during the silk-making process in the ratio 50:50 w/w. These blends were incorporated with moringa seed oil (MSO) as a bio-based plasticizer with different concentrations (1, 2, and 3%) to obtain a final bioplastic with superior antimicrobial properties. The new composites are characterized through Scanning Electron Microscope (SEM), Fourier Transmission Infrared Spectroscopy (FTIR), contact angle measurements, Thermogravimetric analysis (TGA), dielectric, mechanical, and antimicrobial properties. Results of the study pointed to improved linking between the blend phases after incorporating 2% MSO. The composites could inhibit the growth of all the tested microorganisms. The conductivity σ dc values increased by increasing the content of MSO in the composite. The results demonstrate the potential of the new MSO plasticized composites as promising candidates for use in hospitals as antimicrobial surfaces.