•The differences on pyrolysis of PVC polymer and plastics were studied for the first time.•More Cl distributed in the pyrolysis char of PVC pipes compared to that of PVC polymer.•Additives in PVC ...plastics promoted the cracking of heavy fraction in pyrolysis tar.
The organic and inorganic additives in PVC plastics cause great difficulties in their actual recycling process, which are different from pure PVC polymer (PVC-PO). In this study, PVC-PO and two commercial PVC plastics were selected and their differences in structure, pyrolysis behavior, chlorine release and migration were compared by FTIR, TG-MS and a fixed-bed pyrolysis reactor. There were more oxygen-containing functional groups and aromatic compounds in the commercial PVC plastics than PVC-PO because of the addition of foaming agents, flame retardants and lubricants. The thermal weight loss of the commercial PVC plastics was divided into three stages due to the decomposition of additives and the releases of CO2 gas, while that of the PVC-PO was two. The pyrolysis tar of two PVC plastics contained 35.72% and 15.71% oxygenated compounds, respectively, while that obtained from PVC-PO contained 96.46% of aromatic compounds. In addition, calcium additives in PVC plastics could promote the cracking of heavy constituents in the volatile, which was favorable for the formation of more light fractions in tar. The pyrolysis gas of PVC-PO was mainly composed of H2 and C1-C4 hydrocarbon gases, while that of PVC plastics contained about 50% of CO2, followed by H2 and hydrocarbon gases. The chlorine content of the PVC-PO (55.88 wt.%) was higher than that of the PVC plastics (13.83 wt.%, 22.77 wt.%). Most of the chlorine in the three PVC samples released as HCl at 220–370 °C, while the peak temperature of dechlorination of the PVC-PO delayed about 8 °C compared to that of PVC plastics and small part of HCl also released at around 475 °C in the pyrolysis of PVC-PO. About 99.90 wt.% of the chlorine was distributed in the gas phase after PVC-PO pyrolysis, while there were 99.85 wt.% and 97.85 wt.% of chlorine was detected in the gas products of two PVC plastics.
Triboelectric-electromagnetic hybrid nanogenerator (HNG) exhibits exceptional output performance, rendering it a highly viable solution for powering tiny electronics in the foreseeable future. ...However, the construction of a simple structure and light weight HNG using magnetizable triboelectric materials is a highly desirable yet challenging task. Herein, we present a HNG based on flexible neodymium iron boron/polyvinyl chloride (Nd2Fe14B/PVC) composite films for efficiently harvesting mechanical energy from the environment. By embedding Nd2Fe14B powder in PVC matrix, the as-prepared Nd2Fe14B/PVC composites possess desirable triboelectricity and magnetic strength, which is advantageous in replacing traditional heavy magnets to construct a lightweight HNG with high performance. Under a force of 3.8 N and a frequency of 2.1 Hz, the triboelectric nanogenerator (TENG) produces an output power of 4.5 mW at a loading resistance of 5 MΩ, while the electromagnetic generator (EMG) generates up to 0.11 mW at a loading resistance of 200 Ω. The HNG exhibits superior stability and better charging performance compared to single energy harvesting units. A commercial 470 μF capacitor can be charged to 3 V within 385 s through the HNG, which can continuously supply electrical energy to a hygrothermograph and vernier scale. This work provides an effective method for preparing magnetizable triboelectric materials and introduces new possibilities for the rational design of simple structure and lightweight HNGs.
A light-weight and stable hybridized triboelectric-electromagnetic nanogenerator with high-performance is designed based on flexible neodymium iron boron/polyvinyl chloride (Nd2Fe14B/PVC) composite film, which can continuously provide electrical energy for a hygrothermograph and vernier scale. Display omitted
•Design a simple and lightweight hybridized triboelectric-electromagnetic nanogenerator remains a challenge.•The novel magnetizable triboelectric film exhibits desirable triboelectricity and magnetic strength.•A hybridized nanogenerator is constructed based on flexible magnetizable Nd2Fe14B/PVC film.•The hybridized nanogenerator can continuously power a hygrothermograph and vernier scale.•This work provides an effective method for preparing magnetizable triboelectric materials.
•Quantitative analysis about char yield of plastic pyrolysis.•Role of intermolecular chlorine loss on char precursor formation during PVC pyrolysis.•Enhancement of char precursor formation using ...reactive transition metal oxide NiO.
Owing to the importance of controlling the decomposition products of plastic pyrolysis, in this study the mechanisms of char formation in the thermal decomposition of PVC were investigated quantitatively using a kinetic approach. Thermal decomposition behavior of pure PVC, PE, PP, and mixtures of PVC + NiO and PVC + TiO2 powders was probed using a thermogravimetry-differential scanning calorimetry analyzer under an Ar atmosphere from room temperature to 1073 K. Morphological and structural analyses of solid residues were conducted using X-ray diffraction, scanning electron microscopy-energy dispersive spectrometry and Raman spectroscopy. Chlorine was removed from PVC up to 673 K with an activation energy of 104.7 kJ/mol, resulting in 38 % mass of solid residue polyene. When temperature was further increased, the decomposition of polyene occurred almost in the same temperature range of PE and PP decomposition, leading to the final solid residue at 1073 K of 11 %, nil and 1 % for PVC, PE and PP respectively. Central to our examination, two competing routes of chlorine loss in the pyrolysis of PVC (involving intramolecular and intermolecular intermediates respectively) were compared, with respect to their contributions towards char formation. By juxtaposing the pyrolysis behavior of PVC against those of PE and PP, it was deduced that chlorine loss through intermolecular intermediates contributed overwhelmingly to char precursor formation. Theoretical calculations revealed around 35 % of PVC subject to pyrolysis underwent chlorine loss via intermolecular intermediates. This theoretically derived proportionality is in good agreement with experimental results, which indicated a char yield of 28.6 % in the thermal decomposition of PVC. This char formation mechanism was further confirmed by the co-pyrolysis results of PVC with each of two transition metal oxides, i.e. chemically reactive NiO and inactive TiO2, showing that the intermolecular chlorine loss was enhanced in the presence of NiO due to the formation of NiCl2, whereas no obvious change in char yield was observed in case of TiO2 because no chlorination of TiO2 was detected. This combination of experimental and theoretical considerations unanimously verifies that intermolecular mechanisms of chlorine loss in the pyrolysis of PVC play a leading role to the formation of net structures giving rise to char. These findings allude to the possibility of manipulating the decomposition products such as to synthesize net structured carbon based materials through the pyrolysis of waste plastics.
The novel work for this study is to make new films for the pure and doped PVC with organosilane; thus, it used organosilane moieties (25 mg) mixed with poly(vinyl chloride) (5 g). Thus drop-casting ...procedure was utilized to make these thin films. The pure PVC and PVC-organosilane (Si-L-NO
2
/PVC called SI and Si-L-Br called SII) optical properties were studied under the wavelength range from (250 to 1300 nm) using diffusive reflectance equipment. The optical properties like absorption increased up to (87–95%), while reflectance and transmittance decrease when added organosilane molecules. Furthermore, the dielectric constant (real and imaginary) and optical conductivity enhanced, respectively. On the other hand, Urbach energy increases when adding organosilane to PVC structure from 7.7011 to 14.146 eV; furthermore, skin depth, refractive index, and optical density were figured. The energy gap is reduced from 4 to 2.3 eV for the direct transition and from 3.4 to 1.6 eV for the indirect transition. SEM analysis was implemented over thin films of pure PVC and PVC-organosilane to see the morphology of these surfaces. The AFM analysis was utilized to exhibit the topography of the surfaces, thereby finding the surface roughness and the root-mean-square of the surface for these thin films. The improvement for these thin films is used in many applications such as absorption of the light when used as a coating in flat plate collector, and declines the reflectance in radars, strength external applications such as doors, windows, and the dielectric material in electronic devices.
An endotracheal tube (ETT) is a greatly appreciated medical device at the global level with widespread application in the treatment of respiratory diseases, such as bronchitis and asthma, and in ...general anesthesia, to provide narcotic gases. Since an important quantitative request for cuffed ETTs was recorded during the COVID-19 pandemic, concerns about infection have risen. The plasticized polyvinyl chloride (PVC) material used to manufacture ETTs favors the attachment of microorganisms from the human biological environment and the migration of plasticizer from the polymer that feeds the microorganisms and promotes the growth of biofilms. This leads to developing infections, which means additional suffering, discomfort for patients, and increased hospital costs. In this work, we propose to modify the surfaces of some samples taken from commercial ETTs in order to develop their hydrophobic character using surface fluorination by a plasma treatment in SF6 discharge and magnetron sputtering physical evaporation from the PTFE target. Samples with surfaces thus modified were subsequently tested using XPS, ATR-FTIR, CA, SEM + EDAX, profilometry, density, Shore A hardness, TGA-DSC, and biological antimicrobial and biocompatibility properties. The obtained results demonstrate a successful increase in the hydrophobic character of the plasticized PVC samples and biocompatibility properties.
•The behaviour of different HCl-removing materials in PVC pyrolysis is studied.•A powder characterization method to exam chlorinated plastic pyrolysis is developed.•FTIR shows the reactive species ...use and the PVC C–Cl absorption bands suppression.•EDS and FTIR confirm the chlorine salts formed (NaCl, CaCl2 and ZnCl2) in the chars.•Na2CO3-ZnO-based removers exhibited Cl retentions of up to 71 wt.% after pyrolysis.
A powder characterization method was developed to screen the ability of a range of chemicals and absorbents to retain chlorine from chlorinated plastic pyrolysis. The behaviour of adsorbents such as Al2O3 and zeolites, and chemical removers based on NaHCO3, CaO and Na2CO3-ZnO were studied for the removal of HCl released during PVC pyrolysis. First, chlorine removers are mixed with PVC and tested in a thermobalance under pyrolysis conditions for the complete PVC dehydrochlorination (550 °C). Subsequently, after the release of HCl, CO2 and H2O, the chars are analysed by FTIR, CHN elemental analysis and ESEM-EDS to determine the retention of chlorine on the chlorine removers. According to FTIR and CHN, PVC pyrolysis occurs through dehydrochlorination and the formation of aromatics. FTIR and EDS were used to follow the consumption of the bases present in the chemical removers and the suppression of the CCl absorption bands of the PVC CHCl groups during pyrolysis, as well as the formation of the resulting salts (NaCl, CaCl2 and ZnCl2). The chemical removers exhibited chlorine retentions of up to 71 wt. % (using Na2CO3-ZnO), while the adsorbents presented a maximum of 19 % of retention at 550 °C and heating rate of 200 °C/min.
Membrane bioreactors are widely used for industrial wastewater treatment. However, membrane fouling is one of the critical problems in applying these systems. fouling mitigation is an essential issue ...since membrane fouling results in decreased permeability, increased energy consumption, and reduced membrane lifespan which should be addressed in industrial designs. In this study, our objective was to evaluate the filtration performance and fouling behavior of the blended polyvinyl chloride/polycarbonate (PVC/PC) and nanocomposite PVC/PC/modified silver nanoparticles (PVC/PC/MAg) hollow fiber membranes in continuous and intermittent (filtration with backwashing) filtration experiments at constant pressure. Additionally, an experimental module was designed for the backwashing process so that the fouling phenomenon could be investigated step-by-step for both membranes. The performance of the nanocomposite membrane was compared with that of the blended membrane after each backwashing step in terms of flux recovery and fouling resistances. Permeate flux of the blended and nanocomposite membranes at the end of the continuous filtration experiments compared with the initial flux declined by 61% and 48%, respectively. During the intermittent filtration experiments, the average flux of the blended and nanocomposite membranes in the last step decreased by about 16% and 7% in comparison with the first step, respectively. Flux recovery for the nanocomposite membrane at the end of each backwashing step in the intermittent filtration experiment was over 95% resulting in lower permeability decline over the filtration process. Moreover, the present study reveals that incorporating silver nanoparticles into the structure of the PVC/PC membrane results in an increase in permeability and enhancement of antifouling properties, as well as it increases the flux recovery during the backwashing process in MAg-filled nanocomposite membranes.
Display omitted
•The effect of the backwashing process on the fouling behavior of both membranes at each step was investigated.•The backwashing process showed better performance for nanocomposite membranes.•The presence of modified Ag nanoparticles in the blended membrane led to a change in the structure of EPS.•Fouling resistance assessment after each step of the backwashing process was conducted.•The rate of flux recovery in the nanocomposite membrane end of each backwashing step was higher than 95%.
Polyvinyl chloride (PVC) is one of the most commonly used plastics. The treatment and recycling of PVC waste is still challenging, due to its non-biodegradability, low thermal stability, high Cl ...content and low product value. In this study, a one-pot method was developed to upcycle PVC into valuable carbon materials, pipeline-quality pyrolysis gas and chlorides. The well-designed process included dechlorination by Cl-fixative (ZnO or KOH), carbonization of dechlorinated polyenes, and modification of carbon materials in sequence. ZnO and KOH converted 84.48% and 94.15% of total Cl into corresponding chlorides, respectively. CH4 and H2 accounted for 81.87–99.34 vol% of pyrolysis gas with higher heat values of 30.11–32.84 MJ m−3, which can be used as substitute natural gas. As high as 83.13% of the C element was converted into carbon materials. The morphology, structure and property of carbon materials can be modified by different Cl-fixatives. Millimeter-scale carbon spheres with mono-dispersity and porous carbon with a high specific surface area of 1922 m2 g−1 were obtained when ZnO and KOH were added, respectively. Moreover, the reaction mechanisms of PVC with Cl-fixatives were also deciphered through thermogravimetric analysis and thermodynamic simulation.
Display omitted
•PVC were upcycled through one-pot dechlorination-carbonization-modification.•High-yield carbon, pipeline-quality pyrolysis gas and chlorides were obtained.•Structure and property of carbon was modified by adding different Cl-fixatives.•Mechanism of the one-pot reaction has been explored and discussed.
PDF
