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1.
Sci Total Environ ; 734: 139219, 2020 Sep 10.
Artigo em Inglês | MEDLINE | ID: mdl-32450395

RESUMO

In this study, the interaction of emerging pollutant polyvinyl chloride microplastics (PVC MPs) and human serum albumin (HSA) was investigated by fluorescence spectroscopy, UV-visible (UV-vis) absorption spectroscopy, circular dichroism (CD), and Fourier transform infrared (FT-IR) spectroscopy under simulated physiological conditions. Fluorescence results showed that PVC MPs (about 5000 nm in size) can effectively quench the intrinsic fluorescence of HSA through static quenching owing to the formation of HSA-PVC complex. The binding constants (Ka) between PVC and HSA at different temperatures were calculated as 4.97 × 103 M-1, 3.46 × 103 M-1 and 2.51 × 103 M-1, respectively. The number of binding sites was 1.26. The enthalpy change (ΔH), entropy change (ΔS) and free energy change (ΔG) were calculated to be -59.27 kJ·mol-1, 70.76 J·mol-1 K-1 and - 80.35 kJ·mol-1, respectively, indicating that the interaction of PVC with HSA was mainly driven by electrostatic forces. Moreover, results of UV-vis, FT-IR and CD further demonstrated that the microenvironment and secondary structure of HSA were changed a lot induced by PVC, leading to a decrease in α-helix. This work not only provides an insight into the intermolecular interaction between PVC and HSA, but also elucidates the potential biological toxicity of MPs at a molecular level.


Assuntos
Cloreto de Polivinila/química , Humanos , Microplásticos , Ligação Proteica , Albumina Sérica Humana , Espectrometria de Fluorescência , Espectroscopia de Infravermelho com Transformada de Fourier , Termodinâmica
2.
PLoS One ; 15(4): e0228973, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32298267

RESUMO

Electrically conductive composite ultrafiltration membranes composed of carbon nanotubes have exhibited efficient fouling inhibition in wastewater treatment applications. In the current study, poly(vinyl-alcohol)-carbon nanotube membranes were applied to fed batch crossflow electroultrafiltration of dilute (0.1 g/L of each species) single and binary protein solutions of α-lactalbumin and hen egg-white lysozyme at pH 7.4, 4 mM ionic strength, and 1 psi. Electroultrafiltration using the poly(vinyl-alcohol)-carbon nanotube composite membranes yielded temporary enhancements in sieving for single protein filtration and in selectivity for binary protein separation compared to ultrafiltration using the unmodified PS-35 membranes. Assessment of membrane fouling based on permeate flux, zeta potential measurements, and scanning electron microscopy visualization of the conditioned membranes indicated significant resulting protein adsorption and aggregation which limited the duration of improvement during electroultrafiltration with an applied cathodic potential of -4.6 V (vs. Ag/AgCl). These results imply that appropriate optimization of electroultrafiltration using carbon nanotube-deposited polymeric membranes may provide substantial short-term improvements in binary protein separations.


Assuntos
Condutividade Elétrica , Proteínas de Membrana/análise , Membranas Artificiais , Nanotubos de Carbono/química , Cloreto de Polivinila/química , Ultrafiltração , Adsorção , Animais , Galinhas , Eletrodos , Concentração de Íons de Hidrogênio , Eletricidade Estática
3.
Food Chem ; 317: 126465, 2020 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-32114276

RESUMO

Based on the experimental data of gas chromatography-mass spectrometry, an improved artificial neural network was first established to predict the migration of 2-ethylhexyl phthalate (DEHP) plasticizer from poly(vinylidene chloride) (PVDC) into food simulants (ie., heptane, ethanol and water). The sensitivity analysis indicated that temperature acted as a crucial factor influencing the migration values of DEHP. Then, a combined experimental and molecular dynamic (MD) simulation was performed to understand the migration kinetics and the mechanism of DEHP. Hansen solubility parameters of three component (δd, δp, δh) were simplified into two-component solubility parameters (δvdW, δe), and the tuple was successfully applied to describe the interactions between PVDC and food simulants. The MD results showed that high interaction energy and fractional free volume in PVDC/DEHP/food simulant systems accelerated the migration of DEHP. These fundamental studies would provide significant insights into the migration of environmental contaminants.


Assuntos
Dietilexilftalato/análise , Embalagem de Alimentos , Redes Neurais de Computação , Plastificantes/análise , Dietilexilftalato/química , Contaminação de Alimentos/análise , Cromatografia Gasosa-Espectrometria de Massas , Simulação de Dinâmica Molecular , Plastificantes/química , Cloreto de Polivinila/análogos & derivados , Cloreto de Polivinila/química , Solubilidade , Temperatura
4.
Chemosphere ; 249: 126138, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32045755

RESUMO

In this study, subcritical water-NaOH (CW-NaOH) and subcritical water-C2H5OH (CW-C2H5OH) processes were developed for diethylhexyl phthalate (DEHP) degradation and dechlorination of polyvinyl chloride (PVC) waste. The introduction of NaOH or C2H5OH in subcritical water had a noticeable influence on the mechanism of DEHP degradation and dechlorination. For both CW-NaOH and CW-C2H5OH treatments, the increase in temperature could increase dechlorination efficiency (DE) of PVC. The DE of CW-NaOH is much higher than that of CW-C2H5OH under the same conditions. The DE of CW-NaOH could exceed 95% at 300 °C. Hydroxyl nucleophilic substitution was the main dechlorination mechanism in CW-NaOH, while nucleophilic substitution and direct dehydrochlorination were equally important in CW-C2H5OH. In CW-NaOH treatment, 2-ethyl-1-hexanol, benzaldehyde, and toluene were obtained by hydrolysis and reduction reactions of DEHP. Acetophenone was produced by the further cyclization, dehydrogenation and rearrangement reactions of 2-ethyl-1-hexanol. Transesterification was the main degradation pathway of DEHP in CW-C2H5OH at 300 °C. The cyclization and dehydration of 2-ethyl-1-hexanol resulted in producing a high level of ethyl-cyclohexane and 1-ethyl-cyclohexene in CW-C2H5OH at 350 °C. Furthermore, high concentration of ethyl palmitate and ethyl stearate could be prepared in CW-C2H5OH system by the strong reactivity of C2H5OH with the lubricants in PVC.


Assuntos
Dietilexilftalato/química , Etanol/química , Modelos Químicos , Cloreto de Polivinila/química , Álcalis , Halogenação , Hexanóis , Temperatura , Água
5.
Mar Pollut Bull ; 150: 110724, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31759635

RESUMO

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.


Assuntos
Reatores Biológicos , Microplásticos/química , Cloreto de Polivinila/química , Eliminação de Resíduos Líquidos/métodos , Poluentes Químicos da Água/química , Membranas Artificiais , Microplásticos/análise , Plásticos , Cloreto de Polivinila/análise , Águas Residuárias , Poluentes Químicos da Água/análise , Purificação da Água
6.
Molecules ; 24(24)2019 Dec 04.
Artigo em Inglês | MEDLINE | ID: mdl-31817148

RESUMO

Polymerization mother liquid (PML) is one of the main sources of wastewater in the chlor-alkali industry. The effective degradation of the PML produced in PVC polymerization using three or five ozone reactors in tandem was designed with a focus on improving the ozonation efficiency. The ozonation efficiency of the tandem reactors for the degradation of PML, along with the effect of ozone concentration, the number of reactors utilized in series, and the reaction time on the chemical oxygen demand (COD) removal were investigated in detail. The results showed that the COD removal increased as the ozone concentration was increased from 10.6 to 60 mg·L-1, achieving 66.4% COD removal at ozone concentration of 80.6 mg·L-1. However, when the ozone concentration was increased from 60 mg·L-1 to 80 mg·L-1, the COD removal only increased very little. The COD decreased with increasing ozone concentration. During the initial degradation period, the degradation rate was the highest at both low and high ozone concentrations. The degradation rate decreased with reaction time. The rate at a low ozone concentration decreased more significantly than at high ozone concentration. Although high ozone concentration is desirable for COD removal and degradation rate, the utilization efficiency of ozone decreased with increasing ozone concentration. The ozone utilization efficiency of the five-reactor device was three times higher than that of three tandem reactors, demonstrating that ozonation utilization efficiency can be improved by increasing the number of tandem reactors. Ozonation in tandem reactors is a promising approach for PML treatment.


Assuntos
Ozônio/química , Polimerização , Cloreto de Polivinila/química , Purificação da Água/instrumentação , Purificação da Água/métodos , Biodegradação Ambiental , Análise da Demanda Biológica de Oxigênio , Modelos Teóricos , Oxirredução , Fatores de Tempo
7.
Mar Pollut Bull ; 145: 547-554, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31590822

RESUMO

Microplastics are becoming a global concern due to their potential to accumulate pollutants in aquatic environments. In this paper, sulfamethazine (SMT) sorption onto six types of microplastics, including polyamide (PA), polyethylene (PE), polyethylene terephthalate (PET), polypropylene (PP), polystyrene (PS), and polyvinyl chloride (PVC) was investigated by experimental and molecular dynamics simulation methods. The experimental results indicated that SMX sorption reached equilibrium within 16 h. The kinetics of SMT sorption by PA, PVC, PE, and PP could be fitted by pseudo first-order model, while SMT sorption by PA and PET could be described by pseudo second-order model. The partition coefficient Kd values were 38.7, 23.5, 21.0, 22.6, 18.6 and 15.1 L·kg-1 for PA, PE, PS, PET, PVC and PP, respectively. SMT sorption onto microplastics decreased when pH and salinity increased. The molecular dynamics simulation results indicated that the main mechanisms involved in sorption are electrostatic and Van der Waals interaction.


Assuntos
Microplásticos/química , Sulfametazina/química , Poluentes Químicos da Água/química , Adsorção , Concentração de Íons de Hidrogênio , Cinética , Simulação de Dinâmica Molecular , Polietileno/química , Polietilenotereftalatos , Polipropilenos/química , Poliestirenos/química , Cloreto de Polivinila/química , Eletricidade Estática
8.
PLoS One ; 14(10): e0224401, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31658292

RESUMO

Coal gangue has the shortcomings of low calorific value and refractory burnout, while polyvinyl chloride has the advantages of a long combustion process and high calorific value. In order to make up for these shortcomings of coal gangue, the possibility of a treatment method based on co-combustion of coal gangue with polyvinyl chloride, which can be centrally recovered from municipal solid waste, is proposed. In order to analyze the combustion effect of a mixture of these two substances, experimental samples were prepared by mixing these two substances in three different ratios, and they were tested by thermogravimetric analysis. The experimental results were compared, analyzed and evaluated. The effects of the proportion of polyvinyl chloride in the mixture on the temperature parameters, activation energy, and interaction during co-combustion were analyzed. In order to analyze the interaction during co-combustion of the two, a coupling analysis method for mixed combustion is presented, and the effectiveness of this method is verified by comparing with the correlation analysis results of co-combustion. The results show that co-combustion can mitigate the ignition difficulty and burnout of coal gangue. When the proportion of polyvinyl chloride in the mixture was increased from 20% to 80%, the maximum weightlessness rate of the first stage rapidly increased from 4.5%/min to 15.6%/min; however, that of the second stage slowly increased from 3.7%/min to 4.2%/min. A 20% proportion of polyvinyl chloride showed the most significant promotion of co-combustion, with a maximum coupling coefficient of 0.00318, which was 1.11 and 1.35 times greater than that of 50% and 80% proportions, respectively. Co-combustion can reduce the activation energy of coal gangue during the initial and end stages. Therefore, co-combustion is helpful to improve the problems of low calorific value and refractory burnout of coal gangue.


Assuntos
Carvão Mineral , Cloreto de Polivinila/química , Termogravimetria
9.
Molecules ; 24(19)2019 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-31581427

RESUMO

Poly(vinyl chloride) (PVC), a polymer widely used in common household and industrial materials, undergoes photodegradation upon ultraviolet irradiation, leading to undesirable physicochemical properties and a reduced lifetime. In this study, four telmisartan organotin(IV) compounds were tested as photostabilizers against photodegradation. PVC films (40-µm thickness) containing these compounds (0.5 wt%) were irradiated with ultraviolet light at room temperature for up to 300 h. Changes in various polymeric parameters, including the growth of hydroxyl, carbonyl, and alkene functional groups, weight loss, reduction in molecular weight, and appearance of surface irregularities, were investigated to test the efficiency of the photostabilizers. The changes were more noticeable in the blank PVC film than in the films containing the telmisartan organotin(IV) compounds. These results reflect that these compounds effectively inhibit the photodegradation of PVC, possibly by acting as hydrogen chloride and radical scavengers, peroxide decomposers, and primary photostabilizers. The synthesized organotin(IV) complexes could be used as PVC additives to enhance photostability.


Assuntos
Compostos Orgânicos de Estanho/síntese química , Cloreto de Polivinila/química , Telmisartan/química , Ácido Clorídrico/química , Estrutura Molecular , Peso Molecular , Compostos Orgânicos de Estanho/química , Fotólise , Espectroscopia de Infravermelho com Transformada de Fourier
10.
Environ Pollut ; 254(Pt B): 113104, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31472455

RESUMO

Microplastics in water environment and its ability to load various environmental pollutants have attracted wide attention in recent years. However, effect of microplastic size on the adsorption behavior of environmental pollutants and interaction mechanism has not been thoroughly explored. In this study, triclosan (TCS) was selected as model pollutant, and polyvinyl chloride (PVC) with different particle sizes (small size (<1 µm) is recorded as PVC-S and PVC-L means large particle size of about 74 µm) were used as the typical microplastics, the adsorption behavior of TCS on PVC was investigated by studying kinetics, isotherms, and other influencing factors, such as pH and salinity. The results indicate PVC-S has greater distribution coefficient kd values of TCS (1.35 L/g > 1.05 L/g) and stronger adsorption capacity (12.7 mg/g > 8.98 mg/g) compared with PVC-L, which may be due to higher specific surface area, stronger hydrophobicity and relatively small electronegative property of PVC-S. Moreover, the initial pH value and salinity of the solution played crucial role in the adsorption process. The distribution diffusion mechanisms (including liquid-film diffusion and intra-particle diffusion), hydrophobic interaction, electrostatic interaction, halogen bonding, and hydrogen bonding may be the important reasons for adsorption. These findings show that MPs with different particle sizes have vary adsorption behaviors and load capacities for environmental pollutants, which deserve our further concerned.


Assuntos
Tamanho da Partícula , Plásticos/química , Cloreto de Polivinila/química , Triclosan/química , Poluentes Químicos da Água/química , Adsorção , Difusão , Interações Hidrofóbicas e Hidrofílicas , Cinética , Salinidade
11.
Environ Pollut ; 253: 1100-1106, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31434187

RESUMO

A polymer inclusion membrane (PIM) that contains a polyvinyl chloride (PVC) polymer matrix and 1-octanol (OCT) as specific carrier (PO-PIM) was prepared to investigate the mass transfer behaviour of phenol in aqueous solutions. Results showed that the mass transfer behaviour of the PO-PIM for phenol conformed to the first-order kinetics. In addition, the mass transfer efficiency for phenol reached the maximum when the OCT content was 82.8 wt%. The mass transfer activation energy (Ea) was 14.46 kJ mol-1, which indicated that intramembranous diffusion was the main controlling factor in the mass transfer process. The introduction of hydrophobic additives, such as kerosene, liquid paraffin and vegetable oil, into the PO-PIM could remarkably improve its stability. In an aqueous solutions of phenol ranging from 0 mg L-1 to 9000 mg L-1, the initial flux (J0) of kerosene/PVC/OCT-PIM (KPO-PIM) was positively correlated with the initial concentration of phenol. For a stripping solution with a feed solution pH of 2.0 and a sodium hydroxide concentration of 0.1 mol L-1, the maximum permeability coefficient during stable mass transfer reached 12.55 µm s-1. At a mass transfer area of 3.14 cm2, an enrichment factor (EF) of 3.5 for 200 mg L-1 of phenolic aqueous solution was achieved within 48 h through KPO-PIM.


Assuntos
Modelos Químicos , Fenol/química , Polímeros/química , Cloreto de Polivinila/química , 1-Octanol/química , Difusão , Querosene/análise , Cinética , Membranas Artificiais , Água
12.
Colloids Surf B Biointerfaces ; 183: 110438, 2019 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-31470223

RESUMO

This study aims to induce antibacterial and superhydrophobic properties on the surface of thermoplastic polyurethane (TPU) sheets via an improved phase separation process through application of polyvinyl chloride (PVC) thin films. Porous PVC thin films were produced using different amounts of ethanol as nonsolvent. However, the created porosity was not sufficient to achieve superhydrophobicity. To improve the phase separation process, the silver phosphate nanoparticles were first synthesized and then added to the solution. According to scanning electron microscopy and X-ray photoelectron spectroscopy results, the nanoparticles were majorly localized at the bulk of PVC films. A direct relationship was found between the level of porosity and superhydrophobicity. An exceedingly high amount of nanoparticles had a deteriorating influence on porosity and superhydrophobicity. The optimum sample was found to be durable against liquids with different pH values. In contrast to the good resistance of superhydrophobic sample at elevated temperatures (80 °C), a sticky behavior was obtained upon exposure to 120 °C. The level of bacterial adhesion for the superhydrophobic sample was drastically declined (>99%) with respect to the pure PVC film in case of S. aureus and E. coli bacteria after an incubation time of 24 h. In conclusion, the hybrid of superhydrophobic behavior and an antibacterial material such as silver phosphate nanoparticles exhibited a promising potential in achieving antibacterial surfaces.


Assuntos
Antibacterianos/química , Nanopartículas Metálicas/química , Fosfatos/química , Cloreto de Polivinila/química , Compostos de Prata/química , Antibacterianos/farmacologia , Escherichia coli/efeitos dos fármacos , Interações Hidrofóbicas e Hidrofílicas , Nanopartículas Metálicas/ultraestrutura , Microscopia Eletrônica de Varredura , Espectroscopia Fotoeletrônica/métodos , Porosidade , Staphylococcus aureus/efeitos dos fármacos , Propriedades de Superfície
13.
Molecules ; 24(13)2019 Jun 28.
Artigo em Inglês | MEDLINE | ID: mdl-31261834

RESUMO

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.


Assuntos
Naproxeno/química , Compostos Orgânicos de Estanho/química , Cloreto de Polivinila/síntese química , Membranas Artificiais , Estrutura Molecular , Fotólise , Cloreto de Polivinila/química , Propriedades de Superfície , Raios Ultravioleta
14.
Environ Sci Pollut Res Int ; 26(25): 26381-26388, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31290046

RESUMO

A new Schiff base containing 1,2,4-triazole ring system (L) was synthesized and confirmed by 1HNMR, FTIR spectroscopy. The chemical modification of PVC with a new Schiff base (L) was synthesized to produce a homogenous blend (PVC-L). A homogenous blend (PVC-L) was added to copper chloride to produce PVC-L-Cu (II). The PVC films had been irradiated with ultraviolet light for a long period and confirmed by FTIR spectroscopy and weight loss; the surface morphology was inspected by scanning electron microscopy.


Assuntos
Cloreto de Polivinila/química , Triazóis/química , Cobre/química , Espectroscopia de Ressonância Magnética , Microscopia Eletrônica de Varredura , Bases de Schiff , Espectroscopia de Infravermelho com Transformada de Fourier , Raios Ultravioleta
15.
J Appl Clin Med Phys ; 20(7): 176-183, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31207035

RESUMO

Polyvinyl chloride (PVC) is a commonly used tissue-mimicking material (TMM) for phantom construction using 3D printing technology. PVC-based TMMs consist of a mixture of PVC powder and dioctyl terephthalate as a softener. In order to allow the clinical use of a PVC-based phantom use across CT and magnetic resonance imaging (MRI) imaging platforms, we evaluated the mechanical and physical imaging characteristics of ten PVC samples. The samples were made with different PVC-softener ratios to optimize phantom bioequivalence with physiologic human tissue. Phantom imaging characteristics, including computed tomography (CT) number, MRI relaxation time, and mechanical properties (e.g., Poisson's ratio and elastic modulus) were quantified. CT number varied over a range of approximately -10 to 110 HU. The relaxation times of the T1-weighted and T2-weighted images were 206.81 ± 17.50 and 20.22 ± 5.74 ms, respectively. Tensile testing was performed to evaluate mechanical properties on the three PVC samples that were closest to human tissue. The elastic moduli for these samples ranged 7.000-12.376 MPa, and Poisson's ratios were 0.604-0.644. After physical and imaging characterization of the various PVC-based phantoms, we successfully produced a bioequivalent phantom compatible with multimodal imaging platforms for machine calibration and image optimization/benchmarking. By combining PVC with 3D printing technologies, it is possible to construct imaging phantoms simulating human anatomies with tissue equivalency.


Assuntos
Processamento de Imagem Assistida por Computador/métodos , Imagem por Ressonância Magnética/métodos , Imagem Multimodal/instrumentação , Imagens de Fantasmas , Cloreto de Polivinila/química , Radiografia Torácica , Tomografia Computadorizada por Raios X/métodos , Humanos , Imagem por Ressonância Magnética/instrumentação , Tomografia Computadorizada por Raios X/instrumentação
16.
Mar Pollut Bull ; 144: 129-133, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31179978

RESUMO

The effects of time, temperature, and salinity on the adsorption of Tonalide (AHTN), Musk Xylene (MX), Galaxolide (HHCB), and Musk Ketone (MK) by microplastics of polyethylene (PE) and polyvinyl chloride (PVC) are studied. Results indicate that the equilibrium sorption time was about 10 h and the adsorption kinetics model conformed to the first-order adsorption kinetic model and pseudo-second order kinetic model, this indicates that the main adsorption mechanism might be chemical adsorption and physical absorption. Adsorption reached a nadir at 15 °C and 14% salinity. The adsorption capacity gradually increases, and then decreases, finally increases with an increase in NaCl concentration. Due to the specific surface area and the pore volume of PVC was larger than PE, the adsorption capacity of PVC was higher than that of PE in the equal conditions.


Assuntos
Cosméticos/química , Modelos Teóricos , Polietileno/química , Cloreto de Polivinila/química , Poluentes Químicos da Água/química , Adsorção , Benzopiranos/análise , Benzopiranos/química , Cosméticos/análise , Cinética , Polietileno/análise , Cloreto de Polivinila/análise , Salinidade , Água do Mar/química , Tetra-Hidronaftalenos/análise , Tetra-Hidronaftalenos/química , Poluentes Químicos da Água/análise , Xilenos/análise , Xilenos/química
17.
Environ Sci Pollut Res Int ; 26(20): 20769-20779, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31104236

RESUMO

This study sought to identify volatile organic compounds (VOCs) and examine the characteristics of odor-active substances from polyvinyl chloride (PVC)-overlaid medium density fiberboard (MDF). A microchamber thermal extractor was used for sampling, gas chromatography-mass spectrometry was used to identify VOCs, and gas chromatography-olfactometry-mass spectrometry was used to analyze odor-active substances from PVC-overlaid MDF over 28 days. The results showed that 38 VOCs were identified from PVC-overlaid MDF, while only 23 odor-active substances were detected by gas chromatography-olfactometry, which indicated that some VOCs did not generate odor. The main VOCs released by PVC-overlaid MDF were aromatic hydrocarbons, ketones, and esters. There was a strong correlation between concentration and odor intensity of the main VOCs. When the total amount of odor-active substances was not significantly different, the overall odor intensity was determined by the intensity of the key odorants. The greater the intensity of the key odorants, the greater the overall odor intensity. There were eight main classes of odors from PVC-overlaid MDF: aromatic, fresh scent, fruity, sour, sweet, grassy, pungent, and special scent. Among them, the main odor characteristics were aromatic, sour, and fresh scent, which were primarily generated by toluene, ethylbenzene, phenanthrene, and dibutyl phthalate.


Assuntos
Odorantes/análise , Cloreto de Polivinila/química , Compostos Orgânicos Voláteis/análise , Materiais de Construção , Cromatografia Gasosa-Espectrometria de Massas , Olfatometria
18.
Environ Sci Pollut Res Int ; 26(18): 18256-18266, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-31041705

RESUMO

Landfill leachate is generally transferred to in situ facilities for advanced treatment by using a pipe system. Because of its harmful and complex compounds, leachate may react with pipe materials, leading to corrosion and scaling. This experimental study uses typical PVC pipe material and investigates its anti-corrosion performance by placing the material samples into different aged leachates. By evaluating the changes in different experimental parameters, including calcium, magnesium, and chloride ion concentration, oxidation-reduction potential, dissolved oxygen, and pH, combined with a characterization of the material properties, we infer the main causes of pipe scaling-corrosion. Results show that the scaling is more intense in the younger leachate, and the concentration of calcium ions is the dominant influencing factor. The scaling might be resulted from joint actions of chemical precipitation and microbial metabolic activities. It is expected the study to provide useful insights into taking effective actions on anti-clogging, and enhance pipes design by selection of appropriate materials for future modification.


Assuntos
Cloreto de Polivinila/química , Poluentes Químicos da Água/química , Precipitação Química , Corrosão , Oxigênio , Microbiologia do Solo
19.
Molecules ; 24(7)2019 Apr 10.
Artigo em Inglês | MEDLINE | ID: mdl-30974726

RESUMO

Practical applications of Phase Change Materials (PCMs) often require their encapsulation in other materials, such as metals or plastics. This raises the issue of compatibility between PCMs and encapsulating materials, which has still not been sufficiently addressed. The study presented here follows existing research and provides experimental evaluation of the suitability of selected PCMs for proposed integration in building structures. Two organic PCMs, two inorganic PCMs and three representative plastics (polypropylene (PP-H), high density polyethylene (PE-HD) and polyvinylchloride (PVC-U)) were selected for compatibility tests. Evaluation of the results is based on the mass variations of the plastic samples during the test period. Plastic samples were immersed in PCMs and subjected to periodic heating and cooling (for 16 weeks) in a small environmental chamber simulating real operational conditions. The results show that the organic PCMs have a greater ability to penetrate the PE-HD and PP-H compared with the inorganic PCMs. The penetration of all PCMs was most notable during the first four weeks of the experiment. Later it slowed down significantly. Overall, the mass changes in PE-HD and PP-H samples did not exceed 6.9% when immersed in organic PCMs and 1.8% in inorganic PCMs. PVC-U samples exhibited almost negligible (less than 0.1%) mass variation in all cases.


Assuntos
Polietileno/química , Polipropilenos/química , Cloreto de Polivinila/química
20.
Bioresour Technol ; 284: 325-332, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-30953860

RESUMO

The aim of this work aims to synthesize the high performance porous carbons from lignin and rice husk (RH) via one-step pyrolysis with KOH and PVC. And those porous carbons were evaluated for toluene sorption. The unactivated biochars had ultralow specific surface area (SBET). By co-pyrolysis of biomass with KOH, the SBET of bio-carbon was significantly improved. The addition of PVC can further enhance the SBET. Additionally, the SBET of lignin-carbons was higher than that of RH-carbons. It was attributed to the destruction of pore structures in the RH chars with high salts by the washing process. Compared with the RH carbons, the lignin carbons had a higher micro-porosity. As for toluene sorption, the maximum breakthrough time (2195 min) and sorption capacity (263.4 mg g-1) were achieved using LPKC. The textural properties (e.g., pore volume, micro-porosity, and hierarchically porous structure) can take significant effects on the sorption process.


Assuntos
Carbono/química , Lignina/química , Cloreto de Polivinila/química , Tolueno/química , Biomassa , Oryza/química , Porosidade , Pirólise
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