Vinyl Chloride Research Articles

Multi-Objective Optimization and Design for Industrial Vinyl Chloride Reactor by Hybrid Model

The acetylene conversion rate and vinyl chloride production capacity are the main economic indexes for vinyl chloride synthesis, and the reaction temperature is an important operating parameter to prevent the Hg active component from being loss. These three factors have not been taken into consideration simultaneously in the traditional optimization process, making it difficult to achieve optimization targets perfectly for industrial application. To overcome this problem, an efficient strategy framework was proposed based on a hybrid model. Compared with conventional paradigms, the proposed framework could not only reduce computational expense but optimize these two economic indexes with a constrained reaction temperature simultaneously. In addition, a machine learning method was used to conduct a feature analysis, which can reveal the potential interaction between different variables so key variables of this reactor could be identified. To demonstrate and verify this framework, multi-objective optimization involving multiple variables with constrained conditions for the industrial reactor was conducted from design and operation perspectives, respectively. The proposed strategy could provide optimal operational direction for the industrial reactor from these design and operation aspects, which contribute to the sustainable and highly efficient process development in this field. For the first section of an industrial vinyl chloride reactor, this strategy could realize significant improvement in the acetylene conversion rate from 81.34% to over 95.00% and in the vinyl chloride production capacity from 2.60 to above 3.40 mol/h in the operation scenarios, which can meet production requirements. So, the second section of the traditional reactor system is not needed at all.

Topical Anesthesia in Cutaneous Head and Neck Surgery: A Randomized Controlled Trial.

Cutaneous head and neck surgery can safely and effectively be performed using local anesthetic (LA). However, optimizing pain management during LA administration is paramount for patient comfort and procedural efficacy. The primary objective of this study was to investigate the comparative effectiveness of EMLA cream and ethyl chloride (EC) spray in mitigating pain associated with LA administration in cutaneous head and neck surgery. Randomized controlled trial. University-affiliated tertiary head and neck oncology center. Sample size calculation was performed followed by computer randomization into the following groups: EMLA, EMLA placebo (aqueous cream), EC, and a control group (no topical agent). Demographics, pain, and procedural experience scores were recorded perioperatively. Statistical analysis was performed to analyse differences between groups utilizing the Mann-Whitney U test, Kruskall-Wallis test, Chi-square test, and Spearman's Rho. 121 cutaneous lesions with a median patient age of 76 were analyzed. There were no statistically significant differences in pain scores (median [IQR]) between patients receiving EMLA (4 [3.75]), EMLA placebo (4.8 [3.6]), EC (5.8 [2.8]), and no treatment (5 [4.1], P = .19). Procedural experience scores were clinically similar (P = .02). Risk factors associated with elevated nociceptive sensitivity were surgical site (scalp, P = .01), malignant lesions (P < .01) and lesion surface area (rs = 0.22, P = .01). EMLA and EC did not mitigate LA-associated pain in patients undergoing cutaneous head and neck surgery and as such practitioners should reconsider their use of these in this regard. Patients' operative experience remains excellent regardless of topical anesthetic use. Ib.

ATR-FTIR characterisation of daily-use plastics mycodegradation

Synthetic polymers, such as plastics, have permeated all aspects of modern life, and nowadays plastic pollution is a major environmental problem. Mycodegradation of these polymers could represent part of the solution to this problem since it calls on a broad toolbox of enzymes and applies non-enzymatic mechanisms to degrade and deteriorate recalcitrant materials. However, not enough is known about this ability for most of the representatives of the fungal kingdom. Another bottleneck is the harmonisation of technologies to analyse plastic degradation. This work involved the design of a biodegradation experiment, where the potential of four fungi representative of Dikarya and Penicillia (Funalia floccosa, Trametes versicolor, Pycnoporus cinnabarinus and Penicillium oxalicum) were tested on their ability to deteriorate the six most used plastics based on gravimetry and attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR). The following correlation between changes in the band signals and the loss of mass after treatment was determined using polyethylene terephthalate, polypropylene, polyethylene, poly vinyl chloride, high density polyethylene, low density polyethylene and nylon. After treatment, the decrease in absorbance of the characteristic bands of the plastics was taken as an indication of the degradation of the corresponding bonds/functionalities. The four fungi used could transform CH, CH2, CH3, CO, CO, CN, NH and CCl bonds. The best result was obtained using the fungus F. floccosa with 90-day treatments for high density polyethylene (∼ 62.0 %), low density polyethylene (∼ 23.6 %) and nylon (∼ 35.6 %). Therefore, mycodegradation could open up new doors in the fight against plastic pollution.

Synergistic biodegradation of trichloroethylene-contaminated soil using Typha angustifolia L. and an anaerobic degrading bacterial consortium

Plant-microorganism combined bioremediation is a highly efficient and environmentally sustainable method for the remediation of contaminated soils. Despite its potential, the synergistic effects of wetland plants and anaerobic microbial consortium on the removal of chlorinated hydrocarbons (CAHs) from soil remain inadequately understood. In this study, an anaerobic bacterial consortium, capable of completely dechlorinating trichloroethylene (TCE), was enriched and screened from long-term CAH-contaminated soil. Subsequently, the combined effects of the wetland plant Typha angustifolia L. and the anaerobic bacterial consortium on the removal of TCE from soil were investigated, along with the underlying microbial mechanisms. The results demonstrated that the anaerobic bacterial consortium was able to completely convert 0.5 mM TCE to vinyl chloride (VC) within 7 days, and subsequently degrade VC to ethylene within 48 days. The integration of Typha angustifolia L. with the anaerobic bacterial consortium significantly enhanced both the removal and complete dechlorination of TCE from the soil compared to either treatment alone. Furthermore, this combination substantially increased the diversity and richness of soil bacterial communities, enriched dechlorinating microorganisms, and elevated the relative abundance of dehalogenating enzymes and peroxidases involved in pollutant degradation. In addition, the combination resulted in a more complex soil bacterial community, closer microbial interactions, and a more stable microbial co-occurrence network. This study extends the scope of plant-microorganism combined bioremediation for CAH- contaminated soils.

Electrocatalytic dechlorination of chloroethylenes using nitrogen-doped graphene electrodes

Electro-dehalogenation for the clean-up of carcinogenic chloroethylenes (CEs) in groundwater is hindered by the high operating costs of metal electrodes and low efficiency due to competing water reduction and hydrogen formation. This study prepared metal-free electrodes with high Faradaic efficiency (FE) up to 50 % in aqueous solution by coating nitrogen-doped graphene nanoplatelets (N-GPs) on carbon paper. Dechlorination rates at these N-GPs electrodes were enhanced by ∼15 times compared with the plain graphene-based electrode, with first-order rate constants of 0.28, 0.33, 0.41, and 0.048 h−1 for tetrachloroethylene (PCE, 22 μM), trichloroethylene (TCE, 22 μM), cis-dichloroethylene (cis-DCE, 22 μM), and vinyl chloride (VC, 11 μM) dechlorination to acetylene and ethene (VC), respectively, at −1.0 V vs standard hydrogen electrode (SHE), and initial neutral pH. Surprisingly, extremely low N or no-N containing GP was detected from highly reactive N-GPs. Despite the N-doping process has been widely used for improving electrocatalytic reactivity of catalysts by introducing N-functional groups, this study suggests that, the polygonal intrinsic defects formed after N burn-off may act as dechlorination active sites. The N-GP electrodes showed appreciable stable performance over 24 h (five cycles). Simultaneous electrolysis of a mixture of CEs in groundwater without the addition of supporting electrolytes achieved >90 % reduction of PCE, TCE, and cis-DCE and ∼60 % reduction of VC within 24 h at −1.23 V vs SHE, demonstrating its superior performance and great potential of these electrodes in practical applications.

Microdroplet-Mediated Multiphase Cycling in a Cloud of Water Drives Chemoselective Electrolysis.

Electrification of water in clouds leads to fascinating redox reactions on Earth. However, little is known about cloud electrochemistry, except for lightning, a natural hazard that is nearly impossible to harness. We report a controllable electrochemistry that can be enabled in microclouds by fast phase switching of water between the microdroplet, vapor, and bulk phase. Due to the size-dependent charge transfer between droplets during atomization, this process generates an alternating voltage arising from the self-electrification and discharging of microdroplets, vapor, and bulk phase by electron and ion transfer. We show that the microclouds with alternating voltage cause 1,2-dichloroethane (ClH2C-CH2Cl) to be converted to vinyl chloride (H2C═CHCl) at ∼80% selectivity. These findings highlight the importance of controlled cloud electrochemistry in accelerating the removal of volatile organic compounds and treating contaminated water. We suggest that this work opens an avenue for harnessing cloud electrochemistry to solve challenging chemoselectivity problems in aqueous reactions of environmental and industrial importance.

Advanced Poly(vinyl chloride)-Based Membranes Functionalized with Amino Compounds for Vanadium Redox Flow Batteries

Advanced Poly(vinyl chloride)-Based Membranes Functionalized with Amino Compounds for Vanadium Redox Flow Batteries

Preparation of internally‐plasticized poly(vinyl chloride) by grafting hyperbranched cardanol epoxy polyglycerol

AbstractA novel epoxy plasticizer (HCEP) with a hyperbranched polyglycerol structure was synthesized using reduced glycerol and cashew phenol as raw materials. Then it was grafted onto poly(vinyl chloride) (PVC) through click reaction to form self‐plasticized PVC. The structure of the product was characterized with various methods. The effects of the degree of internal plasticizer substitution on the properties of PVC were tested through dynamic mechanical, mechanical property, and thermogravimetric analyses. The amorphous dendritic structure of HCEP effectively enhances the free volume of grafted PVC, leading to a reduction in the glass transition temperature and a significant enhancement in flexibility at room temperature. The maximum elongation at break is 289.89%. The grafting of plasticizers onto PVC avoids the leaching of plasticizers during usage, providing a viable solution for reducing reliance on phthalate‐based plasticizers.

Investigation of Phosphazene Superbase Interactions with [PCl2N]3.

In this study, the reaction between phosphazene superbases and a chlorophosphazene trimer ([PCl2N]3) has been investigated. In this room temperature reaction, the phosphazene superbase (Me2N)3PN(Me2N)2P═NEt, commonly known as P2Et, was shown to behave as a nucleophile, displacing one of the chlorides from [PCl2N]3 and producing the tadpole-like structure 1. The reaction described herein is one of the few instances of a phosphazene superbase behaving as a nucleophile rather than a Brønsted base. Once formed, this structure contains contrasting reactivity, containing a weakly basic phosphazene head while maintaining a highly basic phosphazene tail of the tadpole. The mechanism of the reaction was explored by investigating the potential energy surface through density functional theory calculations at the B3LYP/6-311+G(d,p) level of quantum mechanical theory. It was determined that the reaction of P2Et with [PCl2N]3 followed a stepwise process beginning with the substitution of P2Et onto [PCl2N]3 with the concurrent loss of chloride. Subsequently, the chloride attacks the ethyl group of the P2Et moiety, and ethyl chloride is released, producing 1. Compound 1 was further characterized via 31P NMR spectroscopy, mass spectrometry, and X-ray crystallography.

Insights into the thermal stabilization mechanism of zeolitic imidazolate framework-8 for poly(vinyl chloride)

The thermal stability of zeolitic imidazolate framework-8 (ZIF-8) for poly(vinyl chloride) (PVC) has received attention, but its thermal stabilization mechanism needs further clarification. Herein, the stearic acid-modified ZIF-8 with high specific surface area and large pore volume was effectively synthesized by using zinc stearate as the zinc source for the first time. Modification of stearic acid results in larger adsorption capacity of ZIF-8 for HCl and better thermal stability effect for PVC, especially long-term thermal stability. Moreover, the thermal stability mechanism of ZIF-8 for PVC was demonstrated by experiments and theoretical calculations. In addition to absorbing HCl to eliminate autocatalytic degradation of PVC, ZIF-8 disintegrates and may form 2-methylimidazole-Zn-Cl salt complex instead of free ZnCl2, avoiding the negative zinc burning effect. Furthermore, the Diels-Alder reaction between imidazole ring and degraded PVC prevents the extension of the conjugated double bonds of PVC and delays the deepening of the color of PVC.

Multi‐branched octopus‐like plasticizers with excellent plasticizing performance in poly(vinyl chloride)

AbstractThe development of alternatives is a priority issue for the plasticizer industry due to the reproductive toxicity and potential carcinogenicity of phthalate plasticizers. Herein we demonstrate the synthesis and characterization of multi‐branched octopus‐like plasticizers applied in poly(vinyl chloride) (PVC). The plasticizers were achieved through a straightforward one‐step esterification reaction, resulting in four polyol ester plasticizers (glyceryl tri‐n‐octanoate [GTOE], pentaerythritol tetra‐n‐octanoate [PQOE], xylitol penta‐n‐octanoate [XPOE], and mannitol hexa‐n‐octanoate [MHOE]). The multi‐branched structure enhances the interactions between plasticizers and PVC molecules leading to superior plasticizing properties, particularly mechanical properties, thermal stability, and migration resistance compared with commercial plasticizers di(2‐ethylhexyl) phthalate (DEHP), dioctyl terephthalate (DOTP), and acetyl tributyl citrate (ATBC). Concretely, the elongation at break of MHOE/PVC (825%) and PQOE/PVC (814.63%) was better than that of DEHP/PVC (670.02%), DOTP/PVC (490.62%) and ATBC/PVC (566.78%). The T5% of GTOE/PVC, PQOE/PVC, XPOE/PVC, and MHOE/PVC were 46.97, 67.24, 60.09 and 48.14°C higher than ATBC/PVC respectively. In the volatility resistance testing after 48 h, the weight loss of GTOE/PVC, PQOE/PVC, XPOE/PVC, and MHOE/PVC was 5.63%, 3.64%, 2.95%, and 8.88% respectively, which was far less than DEHP/PVC (15.58%), DOTP/PVC (11.83%) and ATBC/PVC (18.15%). Consequently, the obtained plasticizers demonstrate enhanced plasticizing efficiency, presenting promising alternatives to phthalate plasticizers and expanding the repertoire of choices within the plasticizer industry.

A joint economic evaluation and FP2O techno-economic resilience approach for evaluation of suspension PVC production

The production of polyvinyl chloride (PVC) involves obtaining a thermoplastic polymer from vinyl chloride monomer (VCM) and ethylene, primarily through the suspension method. This process is vital for manufacturing various products, such as pipes and coatings. However, its high-energy consumption necessitates economic evaluations to assess feasibility. In this work, a dual approach is proposed: a Feedstock-Processing-Product-Operation (FP2O) based techno-economic resilience analysis via sensitivity analysis alongside economic evaluation. The study evaluated a PVC production process with a capacity of 518,400 t/y of VCM over a 15-year plant lifespan. The techno-economic assessment revealed a Total Capital Investment of $609, 882, 203, a Payback Period of 4.22 years, and a Return on Investment of 14.38 %. Positive Net Present Value and a cost/benefit ratio >1 indicate the plant's installation under proposed conditions is favorable. Additionally, the technical-economic resilience analysis identified the process's response to changes in PVC price, raw material costs, and production capacity, guiding improvement actions pre- and post-plant assembly.

Viability of strontium carbonate-modified Co3O4 catalysts for chlorinated VOCs oxidation

A series of cobalt oxide catalysts modified with strontium carbonate (Sr:Co molar ratios 0.1–0.4) were prepared, characterised using various techniques (N2 physisorption, XRD, SEM, SEM-EDX, H2-TPR, O2-TPD, XPS) and kinetically evaluated in the gas-phase oxidation of vinyl chloride and 1,2-dichloroethane. Initially, the incorporation of strontium enhanced several physico-chemical properties, including increased surface area, reduced crystal size, and a higher amount of surface oxygen species, suggesting improved catalytic performance. However, the Sr-Co catalysts showed relatively poor catalytic stability, with an increase in chlorinated organic species as catalytic activity decreased. The used catalysts exhibited high concentrations of chlorine, particularly on the surface, along with a decrease in surface area and an increase in crystallite size. Additionally, a reduction in surface oxygen species, crucial for pollutant oxidation, was observed. Therefore, this catalytic chlorination, combined with the loss of textural and structural properties, were inferred to be closely related to catalysts deactivation.

The Transformative Role of Nano-SiO2 in Polymer Electrolytes for Enhanced Energy Storage Solutions

In lithium–polymer batteries, the electrolyte is an essential component that plays a crucial role in ion transport and has a substantial impact on the battery’s overall performance, stability, and efficiency. This article presents a detailed study on developing nanostructured composite polymer electrolytes (NCPEs), prepared using the solvent casting technique. The materials selected for this investigation include poly(vinyl chloride) (PVC) as the host polymer, lithium bromide (LiBr) as the salt, and silica (SiO2) as the nanofiller. The addition of nano-SiO2 dramatically enhanced the ionic conductivity of the electrolytes, with the highest value of 6.2 × 10−5 Scm−1 observed for the sample containing 7.5 wt% nano-SiO2. This improvement is attributed to an increased amorphicity resulting from the interactions between the polymer, salt, and filler components. A structural analysis of the prepared NCPEs using X-ray diffraction revealed the presence of both crystalline and amorphous phases, further validating the enhanced ionic transport. Additionally, the thermal stability of the NCPEs was found to be excellent, withstanding temperatures up to 334 °C, thereby reinforcing their potential application in lithium–polymer batteries. This work explores the electrochemical performance of a fabricated lithium-ion-conducting primary electrochemical cell (Zn + ZnSO4·7H2O|PVC: LiBr: SiO2|PbO2 + V2O5), which demonstrated an open circuit voltage of 2.15 V. The discharge characteristics of the fabricated cell were thoroughly studied, showcasing the promising potential of these NCPEs. With the support of superior morphological and electrical properties, as-prepared electrolytes offer an effective pathway for future advancements in lithium–polymer battery technology, making them a highly viable candidate for enhanced energy storage solutions.

One step beyond for CNSL‐based plasticizers for PVC: Use of cardol

AbstractPoly(vinyl chloride) (PVC) is a widely employed plastic across diverse industries and is often associated with plasticizers, additives that decrease the inherent rigidity and brittleness of the material. Conventional phthalate‐based plasticizers raise substantial toxicity concerns, encouraging the exploration of bio‐based alternatives. One such alternative is the inedible oil, cashew nutshell liquid (CNSL), mainly composed of cardanol and cardol. Recent efforts have focused on developing a cardanol‐based PVC plasticizers but the isolation of cardanol involves time‐consuming, energy‐intensive, and costly steps, limiting its market competitiveness. This study aims to assess for the first time, the efficiency of cardol esters, synthesized using acetic acid and different fatty acids (octanoic acid and myristic acid), in order to evaluate the influence of the alkyl chain on plasticizer properties. The chemical structures of these plasticizers were fully characterized by 1H NMR spectroscopy, and the mechanical properties and thermal behavior of PVC films plasticized with these additives were investigated. Finally, the endocrine activity was evaluated for cardol and cardanol acetates.

ZVI-biochar granules for reactive chlorinated solvent filters generated by high temperature pyrolysis of iron(III) amended biomass

Reactive filters may replace activated carbon filters for degradation of chlorinated solvents in contaminated waters. Reactive porous filter materials with high hydraulic conductivity may be in form of millimeter sized zero valent iron (ZVI)-biochar granules produced via carbothermal reduction. We screened ZVI-biochar materials produced under different synthesis conditions including different iron sources, nitrogen additives and supplementary organic substrates followed by testing adsorption and dechlorination kinetics. Diatomaceous earth was used as an inorganic host reference material. The optimal product from the screening was identified as beech charcoal amended with Fe(III) chloride and urea followed by tube furnace pyrolysis at 1000 °C for 2 h. The millimeter sized granules have a high porosity of 79 %. This material resulted in fast trichloroethylene (TCE, 100–600 µM) sorption and complete dechlorination with acetylene as the main product. It also showed a 5 to 8.5-fold higher degradation capacity than the diatomaceous earth reference system. Fitted pseudo first-order dechlorination rate constants (0.114–0.281 h−1) were comparable to rates reported for powdered ZVI-activated carbon materials. In reactions with high TCE concentrations, Fe(0) consumption for TCE reduction reached up to 93.3 % demonstrating its high selectivity. Reactions with ground material demonstrated that intraparticle diffusion pose minor limitation to dehalogenation rates in the highly porous granules. Further tests demonstrated that the material was further highly reactive to tetrachloroethylene (PCE), cis-1,2-dichloroethyene (cis-DCE) and vinyl chloride (VC). The ZVI-BC material addresses the dual challenges of achieving both high hydraulic conductivity and dehalogenation reactivity, offering a cost-efficient and sustainable option for filter material selection in the remediation of CEs using reactive filters or permeable reactive barriers.

Revisiting the activity of two poly(vinyl chloride)- and polyethylene-degrading enzymes

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.

Impact of TBAI Doping on the Optical and Dielectric Features of PVC/MoO3/NiMoO4/PANI Polymer Composite for Optoelectronic and Energy Storage Applications

Poly (vinyl chloride, PVC)/MoO3/NiMoO4/polyaniline (PANI)/x wt% tetrabutylammonium iodide (TBAI) polymers were formed using casting and hydrothermal methods. The present study examined the nanocomposites’ structural, electrical, and optical features comprising PVC/MoO3/NiMoO4/PANI/x wt%TBAI polymers. X-ray diffraction and scanning electron microscopy were used to investigate the structure and morphology of different samples. The influence of different amounts of TBAI on the linear and nonlinear optical features of PVC/MoO3/NiMoO4/PANI/x wt%TBAI polymers was explored. Adding MoO3/NiMoO4/PANI.TBAI reduced the direct and indirect optical band gaps to their minimum values (3.88, 3.04) eV and (3.58, 2.13) eV, respectively. Doped polymer with MoO3/NiMoO4 has the highest refractive index value. Only PVC filled with MoO3/NiMoO4 exhibits the highest non-linear optical parameters within the visible range. The fluorescence intensity and emitted colors influenced by the kind of dopant. The dielectric constant and ac conductivity values of the host polymer were affected by the amount of TBAI. The maximum energy density value was observed in PVC/MoO3/NiMoO4/PANI/10 wt%TBAI polymer. The Cole-Cole plot demonstrated an irregular shift for doped samples relative to the undoped. The obtained results nominated the nanocomposite films of PVC/MoO3/NiMoO4/PANI/x wt%TBAI to be used in diverse electric and optoelectrical applications.

Corrigendum to “Kinetics of Plasticized Poly(vinyl chloride) Thermal Degradation, Induction, Autocatalysis, Glass Transition, Diffusion.”

Corrigendum to “Kinetics of Plasticized Poly(vinyl chloride) Thermal Degradation, Induction, Autocatalysis, Glass Transition, Diffusion.”

Role of Cyclic Ketene Dithioacetals in Free Radical Polymerization of Vinyl Chloride

AbstractThe role of the sulfur analog of cyclic ketene acetals in the synthesis of polyvinyl chloride is examined in this study. In this context, whether 2‐methylene‐1,3‐dithiolane (S‐CKA5), 2‐methylene‐1,3‐dithione (S‐CKA6), and 2‐methylene‐1,3‐dithiepane (S‐CKA7) monomers are involved in the radical polymerization of vinyl chloride through the ring opening reaction is examined by quantum chemical methods. In light of calculations at the M06‐2X/6‐31+G(d) level, it is concluded that, in general, S‐CKAs undergo little or no ring‐opening and form block copolymers, mainly with the homopolymerization of S‐CKAs and their ring‐retaining step. It is determined that S‐CKA7 is the most prone to ring‐opening reaction and inserting dithioate links to the polymer backbone. However, the radical ring‐opening of S‐CKA7 is strongly reversible, as in other S‐CKAs.