Polyvinyl Chloride Waste Research Articles

Reuse of polyvinyl chloride residues—in powder and fiber forms—as potential components for green mortar pavers

Plastic wastes are considered a significant environmental pollution load because of their mostly non-biodegradable nature. Consequently, the need to lessen the environmental impact calls for employing eco-friendly strategies such as reusing materials in construction. The objective of this study is to analyze the mechanical behavior and environmental impacts of mortar elements, with a specific focus on pavers, by incorporating waste polyvinyl chloride (WPVC) as aggregate and partially replacing cement. Two distinct forms of this waste were considered in the investigation: (i) as it is generated in industrial processes, mainly in fiber form, WPVCf, and in the form of powder obtained by sieving the former, WPVCp. The ratio of conventional mortar materials replaced by WPVC and the final water-to-binder ratio changed based on waste type and mix workability. The experimental work involved preparing 84 pavers, each measuring 100 mm × 150 mm × 60 mm. For each type of paver, 12 samples were prepared, ensuring a minimum of 4 sets of test data for each curing period (7, 14, and 28 days). Flexural strength tests, conducted in accordance with the Colombian standard NTC 2017, utilized a standard flexural test machine with a 150 kN capacity. A specially designed steel tool applied a point load at the center of each paving block, maintaining a minimum distance of 10 millimeters from the edges. The findings demonstrated that pavers containing fiber plastic waste exhibited the requisite strength for paved walkways, even in the short term, when the weight ratio of WPVCf to sand (WPVCf/S) was 24 %. These results derive an eco-friendly solution for reusing PVC wastes currently deposited directly in landfills. Moreover, to analyze the environmental impacts of this solution, a Life Cycle Assessment (LCA) analysis was carried out in this research. The LCA results pointed out that dosing with a WPVCf/S ratio of 24 % emerges as the most ecologically responsible, manifesting substantial reductions across impact categories, such as a significant 23 % decrease in climate change, a 23 % reduction in Photochemical ozone formation, and a 22 % reduction in renewable energy consumption. This underscores the potential of WPVCf incorporation as a consequential step toward eco-friendly construction materials. Furthermore, this solution not only translates to diminished paving block costs by requiring less fine aggregate and cement but also contributes to reduced transportation expenses owing to the decreased weight of the pavers.

Elucidating synergistic effects and environmental value enhancement in infrared-Assisted Co-Pyrolysis of coal and polyvinyl chloride

Co-pyrolysis of high-alkali coal and polyvinyl chloride (PVC) through infrared heating is a promising approach for managing escalating PVC waste and converting low-grade coal resources efficiently. The synergistic effects during co-pyrolysis and thermal degradation of PVC were studied through thermogravimetric analysis (TG-FTIR) and spectral analysis. Furthermore, chlorine migration and chemical transformation integral to the process, along with catalytic interactions, were explored through chlorine mass balance assessment, employing X-ray photoelectron spectroscopy and ion chromatography to establish a groundbreaking understanding of these phenomena. The results of products exhibited a trend of initially increasing and then decreasing with increasing temperatures and mixing ratios. The maximum oil yield was 14.62 %, achieving at 600 °C and 20 %. Meanwhile, the content of aromatic hydrocarbons remained high level through the synergistic interaction of Lewis and Brønsted acid sites, nearly exceeding 60 %. The results showed that the Artificial Neural Network model had a high prediction accuracy with an R2 value of 0.99, while the decarboxylation effect dissociated the metal, resulting in an increase in the fixation of inorganic chlorine from 1 % to 66 % and a decrease in the chlorine content in the liquid phase. Innovatively, the study employs an ANN model for predicting the behavior of co-pyrolysis, exemplifying high accuracy in understanding complex thermal conversions of PVC and coal. Notably, the work challenges existing constraints by applying sophisticated analytical methods to elucidate the thermodynamics and kinetics of the co-pyrolysis processes, thereby enhancing the energetic and environmental value of the products.

PVC Dechlorination for Facilitating Plastic Chemical Recycling: A Systematic Literature Review of Technical Advances, Modeling and Assessment

Polyvinyl chloride (PVC) resins are widely used in modern society due to their acid and alkali resistance, low cost, and strong insulation properties. However, the high chlorine (Cl) content in PVC poses significant challenges for its recycling. This study reviews the treatment processes, model construction, and economic and environmental assessments to construct a methodological framework for the sustainable development of emerging dechlorination technologies. In terms of treatment processes, this study summarizes three types of processes, pretreatment, simultaneous dechlorination during chemical recycling, product purification, and emphasizes the necessity of dechlorination treatment from a systematic perspective. Additionally, the construction of models for dechlorination processes is investigated from the laboratory to the industrial production system to macro-scale material, in order to evaluate the potential inventory data and material metabolism behaviors. This review also summarized the methodology framework of Techno-Economic Analysis (TEA) and Life Cycle Assessment (LCA), which can be applied for evaluation of the economic and environmental performance of the dechlorination processes. Overall, this review provides readers with a comprehensive perspective on the state-of-the-art for PVC dechlorination technologies, meanwhile offering sustainable guidance for future research and industrial applications of chemical recycling of PVC waste.

Effect of interaction between different plastics and polyvinyl chloride on the chlorine transformation behavior in volatiles during low-temperature pyrolysis

To reduce the pollution during the pyrolysis recovery of chlorine-containing plastic waste from different sources, effects of the interaction between different plastics and polyvinyl chloride (PVC) on the transformation of chlorine at low temperature were investigated by thermogravimetry-Fourier transform infrared (TG-FTIR) and fixed-bed pyrolysis experiments. Results showed that the proportions of chlorine in chars were all <0.04 %, indicating that almost all chlorine was released after pyrolysis. However, the chlorine forms in volatiles were significantly changed with mixing different plastics. HCl production was significantly inhibited due to the addition of other plastics, while the organic chlorinated compounds (OCCs) formation was promoted, which increased the distribution of chlorine in liquid products. During PVC pyrolysis, chlorine was mainly distributed in gas (93.09 %) in the form of HCl, only a small amount of aliphatic chlorides were generated and distributed in liquid (6.89 %). After the addition of polystyrene (PS), polyethylene (PE) and polyethylene terephthalate (PET), the chlorine distribution in liquid increased to 8.86 %, 11.98 % and 25.99 %, respectively. The formation of OCCs was significantly affected by the difference in thermochemical reaction characteristics of plastics. Specifically, the production of aromatic chlorides was promoted by PS, while the generation of aliphatic chlorides and aromatic chloroesters was significantly promoted by PE and PET, respectively. Therefore, the release form of chlorine could be significantly altered by the interaction between PVC and other waste plastics, which provides a reference for the regulation of chlorine-containing pollutants in the recovery and utilization of plastic waste.

Thermochemical Valorization of Plastic Waste Containing Low Density Polyethylene, Polyvinyl Chloride and Polyvinyl Butyral into Thermal and Fuel Energy

Pyrolysis is a promising technology for transforming waste plastics (WPs) into high-value products. In the near future it will play a key role in the circular economy, as a sustainable and environmentally friendly method of managing this waste. Although the literature reports on the pyrolysis of plastics, it is focused on pure polymers. On the other hand, the state-of-the-art knowledge about the pyrolysis of mixed and contaminated WPs is still scarce. Industrial waste processing usually uses polymer mixtures containing various impurities that influence the pyrolysis process during chemical WPs recycling. In the paper the pyrolysis of three types of WPs: low density polyethylene (LDPE), polyvinyl chloride (PVC) and polyvinyl butyral (PVB) from repeated mechanical recycling of plastics, as well as their binary and ternary mixtures, is considered. The influence of particular components on the pyrolysis process is analyzed. The aim is to determine synergistic behavior of the mixtures during the pyrolysis process, which is important for increasing the efficiency and quality of the obtained bioproducts. Methods such as thermogravimetric (TG/DTG) analysis coupled with Fourier transform infrared spectroscopy (FTIR) and mass spectroscopy (MS) are used. The variations in the initial and final temperature of pyrolysis, mass loss and mass loss rate are determined. The content of PVC significantly lowers the initial temperature and mass loss and increases the final temperature. The pyrolysis of the considered mixtures shows a noticeable synergism—in the initial stage of pyrolysis up to a temperature around 450 °C, the mass loss is accelerated compared to what is predicted by simple superposition. The inhomogeneity of the mixtures as well as the waste origin causes a significant variation in the activation energy. Three main conclusions are obtained: (i) if the waste does not contain PVC, the pyrolysis is nearly complete at a temperature around 500 °C at a heating rate of 10 °C/min, whereas PVC is not fully processed even at 995 °C; (ii) the synergistic effects affect significantly the pyrolysis process by accelerating some steps and lowering the activation energy; and (iii) the presence of PVC noticeably lowers the temperature of the first stage of PVB pyrolysis. The investigation results prove that chemical recycling of mixed LDPE, PVC and PVB waste can be an effective method of plastic waste management.

Insight into dechlorination of pyrolysis oil during fast co-pyrolysis of high-alkali coal and polyvinyl chloride (PVC)

Thermal treatment can utilize polyvinyl chloride (PVC) in a high-value, eco-friendly method, but HCl generation and high oil chlorine content are key pyrolysis issues. Therefore, this research extensively characterized fast co-pyrolysis of PVC and high-alkali coal (HAC) using XPS, TG-FTIR-GC/MS, and GC-MS. This explored alkali metal catalysis and volatile reforming effects on Cl transfer and utilizing PVC as a hydrogen donor to improve the quality of pyrolysis oil. According to the GC-MS results, increasing the PVC ratio to 40 % raised monocyclic (MAHs) and polycyclic aromatic hydrocarbons (PAHs) to 59.1 % and 33.4 % respectively. However, co-pyrolysis of PVC and HAC inhibited the polyene reconstruction of the carbon skeleton, leading to a decrease of oxygenates, such as phenolic, acid, and ester. The XPS results showed that the inorganic chlorine in the solid product increased from 1 % to 66 % after co-pyrolysis at 600 °C, indicating the high fixed chlorine effect of HAC. Fast heating almost merges the PVC dechlorination stage with the conjugated polyene reconstruction stage, creating a liquid–gas synergy. Abundant coal α-carbon selectively binds with H+, dechlorinated PVC, and polyene fragments, rather than binding with Cl-. This study provides valuable insights into coal-PVC interactions and the dechlorination of pyrolysis oil during fast co-pyrolysis processes and advances the sustainable management of PVC waste.

Designing a sustainable supply chain for battery PVC cases: A multi-objective optimization approach

Nowadays, Polyvinyl Chloride (PVC) and its derivatives are being used in a wide range of products, including car battery cases, due to their corrosion resistance and exceptional durability. As PVC production has grown, the amount of non-hazardous waste generated from PVC products has dramatically increased. In this context, incorporating PVC waste management into the PVC supply chain can effectively address the PVC waste generation issue. This study investigates the design of the Polyvinyl Chloride Closed-Loop Supply Chain (PVCCLSC) based on a triple-objective model for Abadan Petrochemical Company. The first objective aims to minimize the total cost of PVCCLSC, the second objective focuses on minimizing environmental impact, and the third objective maximizes the improvement of Occupational Health and Safety (OHS). In this study, an integrated solution approach is developed encompassing four main phases: (i) Developing an accelerated K-means clustering algorithm, along with the Elbow Method (EM) and Average Silhouette Method (ASM), to estimate the quality of returned PVC products, (ii) Employing a robust optimization method to capture the uncertainty, (iii) Implementing an augmented ε-constraint method to solve the proposed multi-objective model, and (iv) Applying a Bender’s Decomposition Algorithm (BDA) to solve the model and determine optimal solutions. As a result of the proposed BDA, relative optimality gaps have been reduced from 4.56 % in the conventional solution to zeros, and runtime has been reduced from 55 min to 20 min. Furthermore, as a result of this study, more than 44 % of returned PVC products should be recycled using the tertiary method to fulfill environmental requirements.

Utilizing pulverized waste polyvinyl chloride film as an alternative reducing agent for iron ore reduction

The research into using waste plastics as a substitute for coal powder and coke as a reducing agent has garnered significant attention, driven by various factors such as increased environmental concerns and growing interest in sustainable materials. This study investigates the process of carbothermal reduction using a mixture of waste polyvinyl chloride (PVC) and iron concentrate. Thermogravimetric analysis demonstrated that the heat-treated polyvinyl chloride products (PVC370) exhibited superior reaction properties compared to anthracite. Reduction tests indicated that PVC370-bearing pellets were less sensitive to temperature changes than anthracite-bearing pellets, highlighting a potential advantage of PVC370 in industrial applications. Moreover, the metallization ratio of PVC370-bearing pellets exceeded that of anthracite-bearing pellets before reaching 1150 °C. At a temperature of 1100 °C and a C/O of 0.8, the metallization ratio of PVC370-bearing pellets peaked at 83.17 %. During the reduction process of PVC370-bearing pellets, hydrogen (H2), carbon monoxide (CO), and hydrogen chloride (HCl) were efficiently released at relatively low temperatures. The efficiency of gas release in the reduction process could be attributed to certain factors, such as the composition or structure of the PVC370-bearing pellets. Notably, the quality of gasses generated during the reduction process of PVC370-bearing pellets is superior to that of anthracite-bearing pellets, even when considering chlorine content.

Upcycling of PVC waste to high-value sorbent with KOH-activation for efficient removal of organic dyes

Polyvinyl chloride (PVC), known for its chemical stability and flame-retardant qualities, has many uses in various fields, such as pipes, electric wires, and cable insulation. Research has established its potential recovery as a fluidic fuel through pyrolysis, but the use of PVC pyrolysis oil, which is tainted by chlorine, is constrained by its low heat value and harmful environmental effects. This study engineered a layered double hydroxide (LDH) to tackle these challenges. The LDH facilitated dechlorination during PVC pyrolysis and bolstered thermal stability via cross-linking. During pyrolysis with LDH, PVC was transformed into carbon-rich precursors to sorbents. Chemical activation of these residues using KOH created sorbents with a specific surface area of 1495.4 m2 g⁻1, rendering them hydrophilic. These resulting sorbents displayed impressive adsorption capabilities, removing up to 486.79 mg g⁻1 of methylene blue and exhibiting the simultaneous removal of cations and anions.

The Carbon Footprint of Peritoneal Dialysis in Australia.

As climate change escalates with increasing health impacts, healthcare must address its carbon footprint. A critical first step is understanding the sources and extent of emissions from commonly utilised clinical care pathways. We used attributional process-based life cycle analysis to quantify CO2 equivalent emissions associated with the delivery of Baxter home automated peritoneal dialysis (APD) and continuous ambulatory peritoneal dialysis (CAPD) in Australia. Annual per patient carbon emissions attributable to the manufacture and disposal of PD fluids and consumables were 1,992 kg CO2equivalent emissions for APD and 1,245 kg CO2equivalent emissions for CAPD. Transport impacts varied depending on the distance between site of manufacture of PD fluids and consumables and the home state of the patient. As a result, the total impact of providing PD also differed by Australian state, ranging from 2,350-4,503 kg CO2 equivalent emissions for APD and from 1,455-2,716 kg CO2 equivalent emissions for CAPD. Recycling of polyvinyl chloride (PVC) could reduce emissions by up to 14 per cent for APD and 30 per cent for CAPD, depending on the distance between the site of PVC waste generation and the recycling centre. This study demonstrated higher per patient carbon emissions from APD compared to CAPD, due to both higher fluid and consumable requirements, and the consequent higher transport impacts. PVC recycling can partially mitigate PD associated carbon emissions.

PVC waste-derived nanofiber: Simple fabrication with high potential performance for PM removal in air filtration

The utilization of polymer waste in nanofiber membranes is still limited. This study successfully fabricated nanofiber membranes for air filtration using polyvinyl chloride (PVC) waste through electrospinning. The feed solution properties were observed by measuring viscosity and conductivity parameters at varying concentrations of PVC 10–30%, which, indeed, the concentration of PVC greatly affects the microstructure. The smallest fiber diameter was obtained with the addition of 10% PVC. However, it was found that the fiber has beads. Furthermore, the fiber diameter increased with a higher concentration of PVC without the formation of beads, in particular for the PVC concentration > 20%. The ultimate tensile strength was 3.36, 3.97, and 3.67 MPa for 20, 25, and 30% of PVC, respectively. Due to the PVC hydrophobic nature (contact angle value of 100–120°), the PVC waste nanofiber successfully reached the filtration efficiency of 94.35% for PM2.5 and 94.60% for PM0.3 filtration, with a relatively low-pressure drop of 119.12 Pa for fiber membrane with 20% of PVC waste. It implies that the quality factor (QF) is comparable to that of pure-polymer nanofibers or commercial air filters. Thus, the utilization of PVC waste-based nanofiber holds great promise for advancing air filtration systems.

Selective recovery of palladium from wastewater by modified PVC waste pipe

Green, efficient, and cost effective methods of recycling palladium (Pd) from wastewater have attracted increasing attention. In the present study, polyvinyl chloride (PVC) was utilized as a backbone for N-(3-aminopropyl)-imidazole to graft onto and yield an adsorbent suited for selective Pd recovery from wastewater by chlorine coordination. Batch experiments showed that the self-synthesized adsorbent had a Pd(II) adsorption rate of >99% at pH 1.0–3.0 and >93% in 4 min. The selectivity of the adsorbent in a complex mixed system containing high concentrations of typical base metals (CCu(II):CZn(II):CPd(II) = 66:33:1) was investigated, and the adsorbent demonstrated much higher selectivity for Pd (97.59%) than for Cu (0.52%) and Zn (2.96%). The adsorbent can also be reused as the adsorption rate remained above 99% after five cycles. Furthermore, waste PVC pipes also could be used as the synthetic raw material. The adsorbent demonstrated a high adsorption rate even when synthesized from discarded PVC pipes and the adsorption rate reached over 93% in 2 h and reached 95.15% at equilibrium in 4 h. Scanning electron microscopy and energy-dispersive spectrometry, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy were used to analyze the adsorption mechanism, which was attributed to electrostatic interaction and intermolecular interaction. The self-synthesized adsorbent is potentially applicable to the green recovery of Pd from wastewater owing to its high adsorption rate and selectivity.

Stenotrophomonas maltophilia Isolated from the Gut Symbiotic Community of the Plastic-Eating Tenebrio molitor.

Polyvinyl chloride (PVC) waste is a major environmental challenge. In this study, we found that a PVC-eating insect, Tenebrio molitor, could survive by consuming PVC as a dietary supplement. To understand the gut symbiotic community, metagenomic analysis was performed to reveal the biodiversity of a symbiotic community in the midgut of Tenebrio molitor. Among them, seven genera were enriched from the midgut of the insect under culture conditions with PVC as carbon source. A strain of Stenotrophomonas maltophilia was isolated from the midgut symbiotic community of the plastic-eating Tenebrio molitor. To unravel the functional gene for the biodegradation enzyme, we sequenced the whole genome of Stenotrophomonas maltophilia and found that orf00390, annotated as a hydrolase, was highly expressed in the PVC culture niche.

Determination of Resistance to Water-İnduced Damage of Bituminous Mixtures Containing Hydrated Lime Prepared with Different Contents of PVC Waste

Increasing commercial mobility throughout the world has increased the need for roads and as a result, new road networks have emerged. The pavement type of the highways constructed in our country consists of flexible pavements to a significant extent. Parameters such as the number of heavy vehicles, repeated loads as well as environmental and climatic conditions cause different deformations on flexible pavements. One of these deformations is water-induced damage. In particular, changing climatic conditions cause some regions to experience intense precipitation in a very short period of time, which they should receive throughout the year. As a result, flexible pavements are damaged and their service life becomes shorter than expected. With increasing environmental awareness, the use of some waste materials in bituminous mixtures has become an extremely important issue. In this study, bituminous materials modified with different Polyvinyl Chloride (PVC) contents were mixed with properly graded aggregates and their resistance to water-induced damage has been evaluated. In addition, several performance tests were carried out to evaluate the effect of hydrated lime addition on the resistance of the samples to water-induced damage. In this context, the properties of the modified bitumen and aggregates were determined by performing conventional bitumen and aggregate tests. As the final objective of the study, Modified Lottman Test (AASHTO T 283) was performed on the mixtures to determine the effect of PVC addition to bituminous materials on resistance to water-induced damage.

Recycling PVC Waste into CO2 Adsorbents: Optimizing Pyrolysis Valorization with Neuro-Fuzzy Models

Nowadays, the environmental challenges associated with plastics are becoming increasingly prominent, making the exploitation of alternatives to landfill disposal a pressing concern. Particularly, polyvinyl chloride (PVC), characterized by its high chlorine content, poses a major environmental risk during degradation. Furthermore, PVC recycling and recovery present considerable challenges. This study aims to optimize the PVC pyrolysis valorization process to produce effective adsorbents for removing contaminants from gaseous effluents, especially CO2. For this purpose, PVC waste was pyrolyzed under varied conditions, and the resulting solid fraction was subjected to a series of chemical and physical activations by means of hydroxides (NaOH and KOH) and nitrogen. Characterization of the PVC-based activated carbons was carried out using surface morphology (SEM), N2 adsorption/desorption, elemental analysis, and FTIR, and their capacity to capture CO2 was assessed. Finally, neuro-fuzzy models were developed for the optimization of the valorization technique. The resulting activated carbons exhibited excellent CO2 adsorption capabilities, particularly those activated with KOH. Optimal activation conditions include activations at 840 °C with NaOH at a ratio of 0.66 and at 760 °C using either NaOH or KOH with ratios below 0.4. Activations under these experimental conditions resulted in a significant increase in the adsorption capacity, of up to 25%, in the resulting samples.

Stable Efficient Dye‐Sensitized Solar Cell Using Waste Polyvinyl Chloride (PVC) Derived Porous Carbon as Counter Electrode

AbstractAt the time, the world critically requires renewable energy. The challenge is figuring out how to meet expanding global energy consumption. Dye‐sensitized solar cells (DSCs) have attracted a lot of interest due to their high energy conversion efficiency, low cost, environmental friendliness, and easy production procedure. First, the study prepares standard cell platinum, which is the most expensive and in low supply. By replacing PVC‐derived porous carbon for expensive platinum in the DSScs counter electrode. The standard efficiency of platinum counter electrode comes out to be 1.94 and efficiency of PVC derived porous carbon electrode comes out to be 0.46.

Optimal plastic recycling system and technology development could accelerate decarbonization: A case study from Japan

This study provided a geographic and technical matching approach supporting low-carbon style recycling systems, demonstrated using polyvinyl chloride waste (PVCW) generated in 2018 in Mie Prefecture, Japan. From a carbon dioxide (CO2) emission basis, mechanical/material recycling (MR) and energy recovery facilities were all allocated full capacity; however, parts of chemical recycling facilities were excluded in the optimal solutions. From the spatial distribution of the allocated result, we confirmed a trend that to achieve the minimum total emissions, the matchings from pretreatment to recycling facilities were done based on a nearby priority rule. From an emission reduction basis, MR accounted for the major proportion of total reductions which was similar to that accessed from an emission basis. Thus, the promotion of MR should be prioritized at the current technical level when optimizing emissions of the whole lifecycle. The number of facilities allocated were substantially reduced; meanwhile, the averaged emission reductions per ton of PVCW disposed were increased from the current level (2.93) to the near-future level (4.99 t-CO2 t−1). Thus, we concluded that this optimization under a higher technical level was effective to make the current recycling system with more emission reductions (low-carbon environmental effect) and require fewer disposal facilities (cost-saving economic effect). Meanwhile, certain long-distance routes found in solutions implied that technical parameters were more important than geolocation parameters to achieve maximum emission reductions.

High-efficiency co-liquefaction of low-rank coal and PAEs-rich PVC waste in supercritical water: Products upgrading and dechlorination

With the extensive use of phthalates (PAEs)-rich polyvinyl chloride (PVC) plastic products, the recycling of PAEs-rich PVC waste has become a great challenge. Meanwhile, the efficient utilization of low-rank coal is important in China due to the abundant reserves. In this study, a high-efficiency co-liquefaction treatment of PAEs-rich PVC waste and low-rank coal (Inner Mongolia lignite) was developed by using supercritical water (SCW) process based on the interaction between the two kinds of waste. The effects of temperature, time, solid-to-liquid ratio (MCoal+PVC:MH2O), and mass ratio of coal-to-PVC (MCoal:MPVC) on the co-liquefaction conversion, composition of liquefied oil and dechlorination of PVC waste were investigated. The co-liquefaction of low-rank coal and PAEs-rich PVC waste had a significant positive synergistic effect with a maximum synergistic efficiency of 7.53% in the temperature range of 350–450 °C. The conversion ratio of low-rank coal and PAEs-rich PVC waste by SCW co-liquefaction increased from 59.71% to 74.92% with the increase of reaction temperature from 350 to 450 °C. PAEs-rich PVC waste could be almost completely dechlorinated (>98%) by the SCW co-liquefaction process, and more than 90% of the DEHP could be decomposed. The addition of PAEs-rich PVC waste resulted in a significant decrease of the percentage of heteroatom-containing compounds in the oil products by the co-liquefaction. At 450 °C, the co-liquefaction oil contained 69.16% of hydrocarbons and 6.14% of phenolic compounds. Different from supercritical water gasification, the purpose of SCW co-liquefaction in this study is to improve the coal liquefaction conversion ratio and oil quality by introducing the PAEs-rich PVC waste. The synergistic SCW treatment of PAEs-rich PVC waste and low-rank coal has good application prospects in products upgrading of low-rank coal and safe recycling of PAEs-rich PVC waste plastics.

Hydrothermal carbonisation of polyvinyl chloride in ethanol-water/water system for solid fuels: Dechlorination, characteristics analysis of hydrochar, and reaction path

Polyvinyl chloride (PVC) waste plastic is a typical solid waste. In this paper, the dechlorination and carbonization behavior of PVC in ethanol-water/water system under different process parameters (temperature, residence time, solid-liquid ratio) was studied, and hydrothermal carbon was characterized by SEM, elemental analysis, TG-DTG, XPS, Py-GC/MS. The results show that temperature is the key to the hydrothermal dechlorination of PVC, and the dechlorination efficiency of PVC is the highest by parameter optimization (220°C-90 min-10% S/D-80% E/D), which can reach 96.33 %. With the removal of Cl, the surface of the PVC matrix changed from full and smooth flocculent to honeycomb with uniform pore size distribution. Thermogravimetric analysis shows that the combustion of hydrochar can be divided into three stages: HCl precipitation and volatile combustion, semi-coke and coke combustion, and fixed carbon combustion. The combustion parameters and kinetic parameters of hydrochar were measured, and it was found that the hydrothermal carbonization of PVC at higher temperatures and ethanol-water ratio could improve the combustion performance of hydrochar. The highest calorific value can reach 36.68 MJ/mol. Py-GC/MS analyzed the distribution of the pyrolysis products, and alkylbenzene and aliphatic were the main products of pyrolysis. The structural analysis of hydrochar showed that C–C and CC accounted for the largest proportion, accompanied by a small amount of C–O and CO and trace C–Cl. The possible reaction mechanism of the hydrothermal carbonization of PVC was analyzed based on the distribution of functional groups and compound composition. This work provides an effective and sustainable method for the recycling of refractory chlorinated plastics.

Efficient selective uptake of mercury ions using inverse vulcanization-synthesized sulfur-rich adsorbents

Mercury abatement from complex environmental sources remains a significant challenge for environmental protection due to the lack of cost-effective sorbents. Sulfur-based adsorbents have been traditionally used for selective uptake of Hg(II) ions, necessitating the creation of effective sulfur adsorption sites. Herein, we propose a sulfur-rich material synthesized method via inverse vulcanization for mercury removal from solutions. Mercury exhibits an affinity for sulfur, and highly active sulfur sites enhance its adsorption efficiency. Inert elemental sulfur can be activated by aliphatic diamine through a ring-opening process, converting sulfur and polyvinyl chloride (PVC) into functional sulfur-rich materials at a mild temperature of 50 °C. The cross-linked structure of PVC enhances the dispersion of active sulfur sites. This sulfur and nitrogen-containing material demonstrates excellent mercury removal capabilities, exhibiting high selectivity even in complex ionic environments, with a maximum adsorption capacity of 309.2 mg/g. Our results highlight the efficiency of this sulfur-rich material as a mercury sorbent. The inverse vulcanization method enables the efficient utilization of two abundant resources, sulfur and waste PVC. This research has been submitted for publication in a scientific journal, and we have provided a concise and polished version for your consideration.