The chemical industry is one of the main fossil fuel consumers, so its reliance on sustainable and renewable resources such as wind and solar energy should be increased to protect the environment. ...Accordingly, solar-driven thermocatalytic synthesis of octahydroquinazolinone using polyvinylchloride (PVC)-supported aluminum oxide (Alsub.2Osub.3) as a catalyst under natural sunlight is proposed in this work. The Alsub.2Osub.3/PVC catalysts were characterized by FT-IR, SEM, BET, XRD, and XPS techniques. The obtained results indicate that the yield and reaction time can be modified by adjusting the molar ratio of the catalyst. To investigate the stability of the catalyst, the spent catalyst was reused in several reactions. The results indicated that, when a 50% Alsub.2Osub.3 catalyst is employed in an absolute solar heat, it performs exceptionally well in terms of yield (98%) and reaction time (35 min). Furthermore, the reaction times and yield of octahydroquinazolinone derivatives with an aryl moiety were superior to those of heteroaryl. All the synthesized compounds were well characterized by FT-IR, sup.1H-NMR, and sup.13C-NMR. The current work introduces a new strategy to use solar heat for energy-efficient chemical reactions using a cost-effective, recyclable environmentally friendly PVC/Alsub.2Osub.3 catalyst that produces a high yield.
Microplastics have become a major concern in recent years as they can be recognized as the transport vectors for pollutants in environment. In this study, the sorption behavior of two phthalate ...esters (PAEs), including diethyl phthalate (DEP) and dibutyl phthalate (DBP), onto three types of microplastics (PVC: polyvinyl chloride, PE: polyethylene, and PS: polystyrene) was investigated. The sorption isotherms of both DEP and DBP on microplastics were highly linear, suggesting that the partition was the main sorption mechanism. The Kd values of DBP were much higher than those of DEP, demonstrating that hydrophobic interaction governed the partition mechanism. Sorption of the two PAEs on the three microplastics followed the order of PS > PE > PVC, indicating that chemical properties of microplastics played an important roles in their sorption behaviors. Solution pH and natural organic matter had no significant impact on PAEs sorption by microplastics. However, the presence of NaCl and CaCl2 enhanced the sorption of both DEP and DBP because of the salting-out effect. The findings of the present study may have significant implications for the fate and transport assessment of both PAEs and microplastics.
•Sorption of PAEs on the three microplastics followed the order of PS > PE > PVC.•The highly linear sorption isotherms were governed by the partition mechanism.•The presence of NaCl and CaCl2 enhanced the sorption of PAEs on microplastics.•Solution pH and natural organic matter had no significant impact on PAEs sorption.
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.
•Pseudomonas citronellolis and Bacillus flexus are PVC film biodegraders.•PVC biodegradation and fragmentation occurred after 45 days of incubation.•PVC number average molecular weight (Mn) decrement ...of about 10% by bacterial attack.•High (˜19%) gravimetric weight loss observed for waste PVC degraded by P. citronellolis.
The accumulation of high amounts of petroleum-derived plastics in the environment has raised ecological and health concerns. The aim of this work was to study the biodegradative abilities of five bacterial strains, namely Pseudomonas chlororaphis, Pseudomonas citronellolis, Bacillus subtilis, Bacillus flexus and Chelatococcus daeguensis, towards polyethylene, polypropylene, polystyrene and polyvinyl chloride films under aerobic conditions. Preliminary screening resulted in the selection of P. citronellolis and B. flexus as potential PVC film degraders. Both strains were able to form a biofilm on the plastic film surface and to cause some modifications to the FTIR spectra of biomass-free PVC films. The two strains were then used to set up a PVC film biodegradation assay in 2-liter flasks. After 45 days incubation, fragmentation of the film was observed, suggesting that PVC biodegradative activity took place. Gel permeation chromatography analysis showed a reduction in average molecular weight of 10% for PVC incubated with P. citronellolis, with PVC polymer chains apparently attacked. Based on these results, the P. citronellolis strain was selected for biodegradation assays of two waste PVC films, used either nonsterile or subjected to ethanol sterilization. Chemical analyses on the incubated films confirmed the biodegradation of waste PVC plastics as shown by a gravimetric weight loss of up to about 19% after 30 days incubation. In summary, this work reports the biodegradation of PVC films by P. citronellolis and B. flexus. Both strains were shown to act mainly against PVC additives, exhibiting a low biodegradation rate of PVC polymer.
To investigate toxic effects of microplastic on marine microalgae Skeletonema costatum, both algal growth inhibition test and non-contact shading test were carried out, and algal photosynthesis ...parameters were also determined. The SEM images were used to observe interactions between microplastic and algae. It was found that microplastic (mPVC, average diameter 1 μm) had obvious inhibition on growth of microalgae and the maximum growth inhibition ratio (IR) reached up to 39.7% after 96 h exposure. However, plastic debris (bPVC, average diameter 1 mm) had no effects on growth of microalgae. High concentration (50 mg/L) mPVC also had negative effects on algal photosynthesis since both chlorophyll content and photosynthetic efficiency (ΦPSⅡ) decreased under mPVC treatments. Shading effect was not one reason for toxicity of microplastic on algae in this study. Compared with non-contact shading effect, interactions between microplastic and microalage such as adsorption and aggregation were more reasonable explanations for toxic effects of microplastic on marine microalgae. The SEM images provided a more direct and reasonable method to observe the behaviors of microplastic.
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•The toxicity of microplastic depended on their particle size.•The microplastic had negative effects on growth and photosynthesis of microalgae.•Shading effect was not one of reasons for toxic effects of microplastic in this study.•Interactions between microplastic and microalgae observed with SEM technique were direct and reasonable explanations for toxic effects of microplastic.
Interactions between microplastic and microalage were directly and clearly observed with SEM technique to investigate negative effects of microplastic on microalage.
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.
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 microplastics removal and its effects on membrane fouling in membrane bioreactor (MBR) for treating polluted surface water in drinking purpose was investigated in this study. Typical ...microplastics polyvinylchloride (PVC) with concentration 10 particles/L was added in the feed water. MBR was effective in treating organic matters and ammonia with removal rate over 80% and 95%, respectively. The removal performance was immediately inhibited with the microplastics PVC added into the MBR system, and recovered after operated for few days. The membrane fouling and cleaning results indicated that microplastics contamination could led to higher membrane fouling, and also the irreversible membrane fouling. The main contributor of rejection is the membrane module and the adsorption onto bio-carrier. The microbial community of the system before and after PVC addition did not show obvious difference. MBR has the potential to be used as effective technology in treating microplastics contaminated polluted surface water.
•Microplastics contaminated polluted surface water treatment by membrane bioreactor for drinking purpose was investigated.•The effect of microplastics contamination to membrane fouling was characterized.•Microplastics was observed on the fouling membrane surface.
As poly(vinyl chloride) (PVC) photodegrades with long-term exposure to ultraviolet radiation, it is desirable to develop methods that enhance the photostability of PVC. In this study, new ...aromatic-rich diorganotin(IV) complexes were tested as photostabilizers in PVC films. The diorganotin(IV) complexes were synthesized in 79-86% yields by reacting excess naproxen with tin(IV) chlorides. PVC films containing 0.5 wt % diorganotin(IV) complexes were irradiated with ultraviolet light for up to 300 h, and changes within the films were monitored using the weight loss and the formation of specific functional groups (hydroxyl, carbonyl, and polyene). In addition, changes in the surface morphologies of the films were investigated. The diorganotin(IV) complexes enhanced the photostability of PVC, as the weight loss and surface roughness were much lower in the films with additives than in the blank film. Notably, the dimethyltin(IV) complex was the most efficient photostabilizer. The polymeric film containing this complex exhibited a morphology of regularly distributed hexagonal pores, with a honeycomb-like structure-possibly due to cross-linking and interactions between the additive and the polymeric chains. Various mechanisms, including direct absorption of ultraviolet irradiation, radical or hydrogen chloride scavenging, and polymer chain coordination, could explain how the diorganotin(IV) complexes stabilize PVC against photodegradation.
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