Vinyl Chloride Research Articles

Asymmetric Ru-In atomic pairs promote highly active and stable acetylene hydrochlorination

Ru single-atom catalysts have great potential to replace toxic mercuric chloride in acetylene hydrochlorination. However, long-term catalytic stability remains a grand challenge due to the aggregation of Ru atoms caused by over-chlorination. Herein, we synthesize an asymmetric Ru-In atomic pair with vinyl chloride monomer yield (>99.5%) and stability (>600 h) at a gas hourly space velocity of 180 h−1, far surpassing those of the Ru single-atom counterparts. A combination of experimental and theoretical techniques reveals that there is a strong d-p orbital interaction between Ru and In atoms, which not only enables the selective adsorption of acetylene and hydrogen chloride at different atomic sites but also optimizes the electron configuration of Ru. As a result, the intrinsic energy barrier for vinyl chloride generation is lowered, and the thermodynamics of the chlorination process at the Ru site is switched from exothermal to endothermal due to the change of orbital couplings. This work provides a strategy to prevent the deactivation and depletion of active Ru centers during acetylene hydrochlorination.

Thermo‐oxidative degradation behavior of poly(vinyl chloride) insulation for new and overloaded wires via TG‐FTIR

AbstractWhen a poly(vinyl chloride) (PVC) wire experiences overload failure, the internal structure of the insulation changes to become overloaded insulation and the fire hazard changes. In this study, the thermo‐oxidative degradation behavior of new and overloaded PVC insulation materials was analyzed using coupled thermogravimetric‐Fourier transform infrared spectroscopy (TG‐FTIR). The thermo‐oxidative degradation results show that the first two stages of thermo‐oxidative degradation of PVC insulation are important stages for measuring fire hazard. In addition, the onset temperature of thermo‐oxidative degradation of overloaded PVC insulation was increased. The activation energies of the first two stages of the overloaded PVC insulation increased by 7.7% and 27.0%, respectively, compared to the new PVC insulation. And the reaction mechanism is changed. The FTIR results indicate that the increased amount of volatile organic compounds and CO2 generated during the pyrolysis of the overloaded PVC insulation may result in the generation of more heat and smoke during combustion, thus increasing the fire hazard.

A General Approach for Photo-Oxidative Degradation of Various Polymers.

The escalating demand for plastics has resulted in a surge of plastic waste worldwide, posing a monumental environmental challenge. To address this issue, a versatile photo-oxidative degradation method applicable to seven distinct polymer families is proposed, comprising poly(isobutyl vinyl ether) (PIBVE), poly(2,3-dihydrofuran) (PDHF), poly(vinyl acetate) (PVAc), poly(n-butyl acrylate) (PBA), poly(methyl acrylate) (PMA), poly(vinyl chloride) (PVC), poly(dimethyl acrylamide) (PDMA), poly(ethylene oxide) (PEO), poly(oligo(ethylene glycol) methyl ether acrylate) (PEGMEA), and even poly(methyl methacrylate) (PMMA). This method employs photo-mediated hydrogen atom transfer (HAT) followed by oxidation to promote polymer degradation. This reaction is carried out under aerobic condition in the presence of iron trichloride (FeCl3) as a photocatalyst in combination with low-intensity purple light irradiation. The process can degrade up to 97% of the polymer in less than 3 h. This degradation process can be easily controlled by switching the light off, which allows for precise modulation of the degradation rate, enhancing the effectiveness of the method. Overall, this method provides a sustainable method for degrading various polymer types with low energy input.

Theoretical investigation of the OH-initiated atmospheric degradation mechanism of CX2CHX (X = H, F, Cl) by advanced quantum chemical and transition state theory methods.

Halogenated olefins are anthropogenic compounds with many industrial applications but at the same time raising many environmental and health concerns. Gas-phase electrophilic addition of the OH radical to the olefinic CC bond represents the primary sink for these chemicals in the atmosphere, with the degree and type of halogenation playing a significant role in their overall reactivity. In this work, we present a theoretical investigation of the reaction mechanisms and kinetics for the reactions between the OH radical and CH2CH2 (ethylene, ETH), CF2CHF (trifluoroethylene, TFE) and CCl2CHCl (trichloroethylene, TCE), simulated by state-of-the-art protocols and methods, with the aim of providing a detailed interpretation of the available experimental results, as well as new data of relevance to tropospheric chemistry. Specifically, potential energy surfaces (PESs) are obtained using the jun-Cheap (jChS) composite scheme, whereas temperature and pressure dependent rate coefficients and product distributions in the 100-600 K temperature range are calculated within the Rice-Ramsperger-Kassel-Marcus/master equation (RRKM/ME) framework. The rates for barrierless channels are obtained from variable reaction coordinate-variational transition state theory (VRC-VTST) combined with the two transition state model. While the reactions with ETH and TFE proceed mainly via the formation of addition adducts at P = 1 atm and T = 298 K, the dominant channel for TCE is the Cl-elimination reaction. Global rate constants for the two halogenated olefins, TFE and TCE, are found to be pressure-independent, contrary to the case of ETH. The computed rate constants, as well as their temperature and pressure dependence, are in remarkable agreement with the available experimental data, and they are used to derive atmospheric lifetimes (τ) for both TFE and TCE as a function of altitude (h) in the atmosphere, by taking into account variations in the rate coefficients (k (T, P)) and [OH] concentration.

Boosting poly(vinyl chloride) with waste-based plasticizer and green nanofiller

Boosting poly(vinyl chloride) with waste-based plasticizer and green nanofiller

Continuous-flow synthesis of di-(2-ethylhexyl) peroxydicarbonate in a packed-bed microreactor: Process optimization and kinetic modeling

Di-(2-ethylhexyl) peroxydicarbonate (EHP) is a low-temperature liquid organic peroxide commonly used as an initiator for polymerization of vinyl chloride and ethylene. The exothermic nature of peroxidation and the instability of this peroxide product pose safety challenges during synthesis. Therefore, batch reaction processes for synthesizing such products often prioritize safety over efficiency. In this work, an efficient and safe protocol was proposed for EHP production with the use of a packed-bed microreactor. Response surface methodology was applied to optimize critical process parameters, resulting in a remarkable yield of 95.48% in a residence time of 23.8 min. It proves that the efficiency was significantly improved by the packed-bed microreactor compared with batch reactors. Additionally, an operational window was established to guide the process development for synthesizing EHP in flow. Finally, a kinetic model was established, which was of crucial theoretical significance and practical value for better understanding peroxidation processes and parameter optimization.

Polymers in the Textiles and in the Construction Industry

Ionic solids, ceramics and most polymers and plastics are insulators, they do not conduct electrical current. Plastics are materials that can be formed into various shapes by the application of pressure or heat. Plastics are classified into thermosetting plastics, thermoplastic material, or an elastomer. A thermosetting plastic cannot be reshaped readily as it’s made from an irreversible reaction. Thermoplastic materials can be reshaped, for example polyethylene polymer used in the making of milk containers. Elastomers are plastics with elastic behavior or rubbery plastics, as they can be subject to stretching and bending. Polymers can be either naturally occurring from animals or plants or synthesized in chemical plants or chemical laboratories. This work is aimed to identify the polymers that are used in the textile industry and the polymers used as fill in materials in the construction industry, to find polymers that are less toxic with similar properties as PVC in the textile industry due to the environmental concerns that comes with using PVC, to know whether poly vinyl chloride is still used in the textile industry in the United States, and to find suitable polymers used as fill material in the construction industry.

Adsorption of metals on aged microplastics in intensive mariculture areas: Aggravating the potential ecological risks to marine organisms

Field determination of the metal adsorption capacity of microplastics (MPs) by using a passive sampler had been done in typical subtropical mariculture area in China. The adsorption of eight metals (Fe, Mn, Cu, Zn, As, Pb, Cr and Cd) by five types of MPs (low-density polyethylene, polypropylene, polystyrene, poly(ethylene terephthalate) and poly(vinyl chloride) (PVC) was compared, including metal types, mariculture types (cage and longline culture), metal residue content in ambient environment, polymer types and particle sizes of MPs. The results showed that Cu, Zn, As, Cd, Pb and Cr in the mariculture environment were contaminated compared with the quality criteria. The concentrations of these six metals adsorbed on five MPs increased linearly with those in seawater. More enriched Cu and As in MPs in marine cage culture than in longline culture, due to the obvious endogenous pollution emissions for the artificial diets, fish medicine and disinfectants. Aged PVC with more cracks and pores showed higher metal adsorption capacity than any other polymers. MPs with a smaller size range of 50–74 μm tended to accumulate higher amounts of metals than those with a larger size range of 74–178 μm, consisting with the surface characteristics of MPs. The significant positive relationship between the concentrations of nutrients in seawater and the adsorption amounts of Cu, Zn and As on MPs implies that the eutrophication would promote their pollution. Based on the ecological risk assessment, the occurrence of MPs could aggravate the potential risk of metals to marine organisms in intensive mariculture areas. This is the first time to reveal the impacts of the adsorption of metals on aged MPs on the potential ecological risks of metals to organisms under the realistic environmental condition.

Is ethyl chloride the new nitrous oxide? A case report

BackgroundOver the last decade, there has been an emerging trend of recreational misuse of several drugs and inhaled solvent including ethyl chloride. This case report follows CARE guidelines and highlights, with supporting video, the neurological features of ethyl chloride intoxication.Case presentationA 48-year-old man was seen for the sudden occurrence of an unsteady gait with dizziness. His only medical history was a chronic and treated HIV infection without any complications. Clinical examination revealed a cerebellar syndrome associated with impairment of short-term memory. Biological and radiological workups were normal. After several days, the patient recalled ethyl chloride inhalation. He fully recovered after being discharged from hospital.ConclusionClinicians should recognise the clinical features and neurological manifestations of ethyl chloride intoxication due to the potential fatal cardiovascular complications of this intoxication.

Metal immobilized in a USY zeolite-supported (4-CB)TPPB: A new strategy of enhanced stability for acetylene hydrochlorination

Palladium (Pd)-based catalysts supported by silicaluminate materials are potential as the efficient non-mercury catalyst for acetylene hydrochlorination, which is a necessary industrial reaction for producing vinyl chloride monomer. A new strategy was employed to improve Pd/USY zeolite catalysts taking advantage of 4-carboxybutyl triphenylphosphonium bromide ((4-CB)TPPB) for acetylene hydrochlorination. The most active catalyst (Pd@20(4-CB)TPPB/USY) with the 0.5 wt% Pd loadings and the 20 wt% (4-CB)TPPB additives could achieve a stable acetylene conversion of 99.9 % and the vinyl chloride selectivity of 99.7 % during more than 50 h, outperforming the Pd/USY catalyst. The additive of (4-CB)TPPB was preferential to stabilize the catalytic active Pd species, inhibit the Pd (II) reduction and change the surface acidic properties during the preparation process and reaction, hence restraining the carbon deposition. Density functional theory (DFT) calculations further indicate that (4-CB)TPPB additives could effectively enhance the adsorption energy of catalyst for reactants and the desorption energy of vinyl chloride monomer (VCM) products, thus inhibiting the carbon deposition for improving the catalytic performance of Pd/USY catalysts. These findings provide guidance for designing efficient Pd-based catalysts as well as their utilization for acetylene hydrochlorination.

Carcinoembryonic antigen and cancer antigen 125 simultaneously determined using a fluidics-integrated dual carbon electrode

Carcinoembryonic antigen (CEA) and cancer antigen 125 (CA125) are important tumor markers for the diagnosis of ovarian cancer at the metastasis stage. Here, CEA and CA125 were simultaneously detected by a label-free electrochemical immunosensor. Using a stencil and carbon ink, a dual carbon electrode (DCE) was fabricated on a poly(vinyl chloride) substrate. Gold particles (AuPs) were electrodeposited on the electrode as a signal amplifier and support for immobilized antibodies. Linear sweep voltammetry was utilized to detect the tumor markers based on the specific binding of antigens to antibodies. Scanning electron microscopy and atomic force microscopy were used to characterize the fabricated DCE. The results were compared to those of a commercial DCE. Using the developed DCE immunosensor, we achieved a linear range of CEA from 0.5 to 25 ng mL−1 and a linear range of CA125 from 2 to 50 U mL−1. The limits of detection of CEA and CA125 were 0.15 ng mL−1 and 0.6 U mL−1, respectively. The reliability of the immunosensor was evaluated using human serum. The results were consistent with those obtained from the reference enzyme-linked fluorescence assay. The immunosensor was integrated with a small plasma membrane to form a fluidic cell (Flu-iDCE) based on acrylic sheet. The membrane had no effect on the detection of the tumor markers with the proposed Flu-iDCE. This first report of a fluidic device integrated with a DCE demonstrates the potential of the device for point-of-care detection of CEA and CA125.

Evaluation of Green Biobased Plasticizers in Poly(vinyl chloride): Sustainability, Thermal Behavior, Mechanical Properties, and Durability

Evaluation of Green Biobased Plasticizers in Poly(vinyl chloride): Sustainability, Thermal Behavior, Mechanical Properties, and Durability

Effect of Metal Oxides Nanoparticles on the Optical Properties of Poly(vinyl chloride)/Poly(vinylidene fluoride) Blends Electrolytes Plasticized with Glycerol

Effect of Metal Oxides Nanoparticles on the Optical Properties of Poly(vinyl chloride)/Poly(vinylidene fluoride) Blends Electrolytes Plasticized with Glycerol

A data-driven robust optimization method based on scenario clustering for PVC production scheduling under uncertainty

In this paper, a data-driven robust optimization method based on scenario clustering is proposed for addressing energy consumption uncertainty characterized by correlation and multi-peaked distribution within the PVC production process. Firstly, principal component analysis (PCA) and kernel density estimation (KDE) methods are used to capture the correlation and distribution information effectively across multidimensional uncertain parameters; then a modified K-means clustering method based on density peaks is applied to cluster energy consumption scenarios and the flexible uncertainty subsets is established. A two-stage robust optimization model for the vinyl chloride production section is then proposed, and the column and constraint generation algorithm is applied to solved. Finally, the effectiveness of the proposed method is validated through a PVC production case study. Comparative results demonstrate that the proposed model reduces energy consumption under uncertainty and improves the robustness of PVC production scheduling.

Influence of parameter variation intervals on pyrolysis sensitivity analysis for charring and non-charring materials

This study applies the Morris method for a sensitivity analysis to evaluate the input parameters’ influence on the heat release rate in a pyrolysis model, focusing on two materials, poly(methyl methacrylate) (non-charring) and poly(vinyl chloride) (charring), examined under a cone calorimeter. A key aspect of our exploration was the role of input parameter variation intervals on the sensitivity outcomes. We analyzed three interval-setting methods: 1. A standard ±10% deviation from the nominal value, commonly used in the literature. 2. A range determined by the experimental uncertainties for individual parameters. 3. A span from minimum to maximum values found in existing literature for each parameter. Our intensive literature review supported the framing of intervals for the latter two methods. Our findings underscore the critical role of the selected variation interval. Specifically, while a uniform ±10% variation identified activation energies as the primary influencers—consistent with prior literature—the introduction of experimental uncertainties shifted this prominence toward heats of reaction. Thus, the selected interval can drastically reshape the perceived importance of certain parameters. This original work challenges the traditionally employed variation ranges in sensitivity studies, emphasizing the need for a nuanced approach.

Enhanced in situ bioremediation of chlorinated ethenes: from in situ microcosms to full-scale application

Concentrations greater than 20 mg/L of chlorinated volatile organic compounds (cVOCs) including tetrachloroethene (PCE), trichloroethene (TCE), and cis-1,2-dichloroethene (cDCE) have been present in site groundwater for more than four decades. To promote a faster clean-up time, an in situ bioremediation approach was evaluated using In-Situ Microcosms® (ISMs) followed by a full-scale in situ bioremediation approach. The ISM study evaluated slow-release versus quick-release carbon substrates with and without bioaugmentation using the chlorinated ethene degrading culture, SDC-9™. After a three-month incubation period, the ISMs were retrieved. The ISMs amended with a carbon source with or without bioaugmentation displayed greater than a 93% reduction in TCE, which corresponded to an increase in cDCE in all the ISMs. The Dehalococcoides population and gene abundances associated with chlorinated ethene biodegradation (tceA, bvcA, vcrA) increased three orders of magnitude in the bioaugmented ISMs over the natural attenuation ISM and carbon source only amended ISMs. Additionally, the SDC-9™ and AquaBupH®, an enhanced emulsified oil substrate (EOS®) and buffer, amended ISM unit showed the highest level of vinyl chloride and similar level of ethene to the SDC-9™ and EHC®, a controlled-release, organo-iron substrate, ISM. However, the AquaBupH and SDC-9™ ISM displayed the highest level of acetate, demonstrating active fermentation processes. The results of the ISM study indicated that a combined approach of biostimulation along with bioaugmentation effectively promoted conditions conducive to reductive dechlorination. The full-scale in situ bioremediation system coupled biostimulation with bioaugmentation using SDC-9™ to successfully reduce chlorinated ethenes in groundwater. The slow-release carbon substrate, EOS-100® served as a sustained carbon source along with CoBupH (buffering agent similar to AquaBupH), facilitating the production of hydrogen, through volatile fatty acid fermentation. This led to the reduction of chlorinated ethenes over the subsequent three years, showcasing minimal rebound in contaminant levels. Two rounds of bioaugmentation notably increased the Dehalococcoides population, accelerating the biodegradation processes, which is setting up the site for monitored natural attenuation. This study shows that using ISMs to guide full-scale bioremediation design resulted in an effective cVOC biodegradation system that led to quicker and more sustainable clean-up.

Comparison of numerical calculations and ALOHA modeling in consequence assessment of chlorine gas emissions from ethylene dichloride reactors.

Incidents involving chemical storage tanks in the petrochemical industry are significant events with severe consequences. Within the petrochemical industry, EDC is a sector that produces ethylene dichloride through the reaction of chlorine and ethylene. The present research was conducted to evaluate the consequences of chlorine gas released from the EDC reactor in a petrochemical industry in southern Iran. Data regarding reactor specifications were obtained from the factory's technical office, while climatic data was acquired from the Meteorological Organization. The consequences of chlorine gas release from the reactor were assessed in four predefined scenarios using numerical calculation methods and modeling with the ALOHA software. The numerical calculation method involved thermodynamic fluid path analysis, discharge coefficient calculations, and wind speed impact analysis. The hazard radius was determined based on the ERPG1-2-3 index. Results showed that in the scenario of chlorine gas release from EDC reactors, according to the ALOHA model, an increase in wind speed from 3 to 7m/h led to an expanded dispersion radius. At a radius of 700m from the reactor, the maximum outdoor concentration reached 3.12ppm, decreasing to 2.27ppm at 800m and further to 1.53ppm at 1000m. The comparison of numerical calculations and modeling using the ALOHA software indicates the desirable conformity of the results with each other. The R2 coefficient for evaluating the conformity of the results was 0.9964, indicating the desired efficiency of the model in evaluating the consequences of the release of toxic gasses from the EDC tank. The results of this research can be useful in designing the site and emergency response plan.

The Potential of AOP Pretreatment in the Biodegradation of PS and PVC Microplastics by Candida parapsilosis

Microplastics are an emerging class of recalcitrant organic pollutants that are of general scientific and public interest nowadays. It would be ideal to remove microplastics from the environment through biodegradation, as biodegradation is a highly ecological and economically acceptable approach. Unfortunately, the efficiency of biodegradation of conventional plastic polymers is low. The application of a suitable pretreatment could increase the efficiency of biodegradation. In this study, the applicability of UV-C/H2O2 and UV-C/S2O82− advanced oxidation processes as pretreatments for the biodegradation of polystyrene and poly(vinyl chloride) microplastics by the yeast Candida parapsilosis was investigated. For the investigated range (pH 4–10, peroxide concentration up to 20 mM and treatment duration up to 90 min), the UV-C/H2O2 process proved to be more effective in degrading polystyrene microplastics, while the UV-C/S2O82− process was more efficient at degrading poly(vinyl chloride) microplastics. Samples pretreated under optimal conditions (90 min treatment time at a pH of 5.7 and H2O2 concentration of 20.0 mM for polystyrene samples; 90 min treatment time at a pH of 8.6 and S2O82− concentration of 11.1 mM for poly(vinyl chloride) samples) were subjected to biodegradation by Candida parapsilosis. The biodegradation conditions included an agitation speed of 156 rpm and an initial pH of 5.7 for the experiments with the polystyrene samples, while an agitation speed of 136 rpm and an initial pH of 4.9 were used for the poly(vinyl chloride) experiments. The initial value of the optical density of the yeast suspension was 1.0 in both cases. The experiments showed a positive effect of the pretreatment on the number of yeast cells on the surface of the microplastics.

Preconcentrating extractive polymeric network in paper-based sensing of copper

The concept of using an extractive polymeric sensing network on a paper-based substrate for the pretreatment of samples in the colorimetric analysis of heavy metals is demonstrated with the determination of Cu2+ in aqueous samples. The newly developed paper-based device combines the advantages of both liquid–liquid extraction-based separation and the analytical capabilities of microfluidic paper-based analytical devices (μPADs). The preconcentrating extractive polymeric network composed of 53.5 wt% poly(vinyl chloride) (PVC), 45 wt% extractant (di-(2-ethylhexyl)phosphoric acid (D2EHPA)) and 1.5 wt% dye (1-(2′-pyridylazo)-2-naphthol (PAN)), coated on filter paper, shows good water-wicking properties, allowing the transmission of high sample volumes. This results in significant analyte preconcentration. The extractant (D2EHPA) selectively binds Fe3+ and Zn2+ which otherwise will compete with Cu2+ in its colour reaction with PAN at the chosen pH of 3.0. The device’s capacity to process higher sample volumes resulting in higher sensitivity is increased by the integration of several filter paper absorption layers. The optimized device is characterized by a limit of detection (LOD) for tap and environmental waters of 3.4 and 9.6 µg/L, respectively; stability of 51 days if stored in a refrigerator; and total analysis time (from sample insertion to colour detection) of less than 5 min.

Achieving Enhanced Dielectric and Energy Storage Performance in Poly(vinyl chloride-glycidyl methacrylate) through Tuning Interchain Interactions.

Glassy polymer dielectrics exhibit significant advantages in energy storage density and discharge efficiency; however, their potential application in thin-film capacitors is limited by the complexity of the production process, rising costs, and processing challenges arising from the brittleness of the material. In this study, a small amount of the polar monomer glycidyl methacrylate (GMA) was copolymerized with vinyl chloride (VC) using a highly integrated and precisely controlled process. This effectively facilitated the bulk synthesis of P(VC-GMA) copolymers, aimed at enhancing the dielectric properties and energy storage capabilities of the copolymer. Moreover, the incorporation of GMA into PVC induces significant alterations in the structural sequence of the copolymer, resulting in an enhancement of interchain interactions that ultimately contribute to an increase in the modulus and improved breakdown strength. With a GMA content of 2.4 mol %, P(VC-GMA) exhibits a significant enhancement in discharge energy density, surpassing that of a pure PVC copolymer, while maintaining high discharge efficiency and stability. The finding of this study paves the way for future advancements in high-energy-storage polymer dielectrics, thereby expanding the scope of advanced dielectric materials.