Addition Of Polyvinyl Chloride Research Articles

Upcycling PVC and PET as Volume-Enhancing Functional Fillers for the Development of High-Performance Bio-Based Rigid Polyurethane Foams

Polyvinyl chloride (PVC) and polyethylene terephthalate (PET) contribute significantly to global plastic waste, with only 9% recycled in recent years. In this work, these plastic wastes were upcycled as functional fillers to improve the rigid polyurethane foam (RPUF) properties. To attain this target, we leveraged the intrinsic polarity of the C=O and C-Cl groups of PVC and PET to induce intermolecular attractions with the N-H groups of the polyurethane matrix, evidenced by the observed IR peak shifts. This enhanced the nucleating effect during foaming, increasing the foams’ compressive strengths by 77% and 22% with the addition of 10% PVC and 5% PET filler, respectively. Furthermore, the addition of PVC and PET fillers increased the foam volume. Thus, the collective utilization of PPW and its corresponding impact on the CO-based RPUF’s properties signifies a reduction in carbon dioxide emissions by 14.15% and 17.52% for PVC and PET, respectively. Moreover, thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) revealed improved thermal stability and degradation profiles of the produced RPUFs. Overall, this work highlights potential advancement in environmentally responsible upcycling strategies for common end-of-life plastic wastes, while enhancing rigid foam properties.

Polyvinyl chloride and polybutylene adipate microplastics affect peanut and rhizobium symbiosis by interfering with multiple metabolic pathways

Microplastics (MPs), widely presented in cultivated soil, have caused serious stresses on crop growth. However, the mechanism by which MPs affect legumes and rhizobia symbiosis is still unclear. Here, peanut seedlings were inoculated with Bradyrhizobium zhanjiangense CCBAU 51778 and were grown in vermiculite with 3 %/5 % (w/w) addition of PVC (polyvinyl chloride)-MPs/PBAT (polybutylene adipate)-MPs. PVC-MPs and PBAT-MPs separately decreased nodule number by 33–100 % and 2.62–80.91 %. Transcriptome analysis showed that PVC-MPs affected more DEGs (differentially expressed genes) than PBAT-MPs, indicating PVC-MPs were more devastating for the symbiosis than PBAT-MPs. Functional annotation revealed that PVC-MPs and PBAT-MPs enriched DEGs related to biosynthesis pathways such as flavonoid, isoflavonoid, and phenylpropanoid, in peanut. And when the dose increased from 3 % to 5 %, PVC-MPs mainly enriched the pathways of starch and sucrose metabolism, alanine, aspartate and glutamate metabolism, diterpenoid biosynthesis, etc.; PBAT-MPs enriched cysteine and methionine metabolism, photosynthesis, MAPK signaling, and other pathways. These significantly enriched pathways functioned in reducing nodule number and promoting peanut tolerance to MPs stresses. This study reveals the effect of PVC-MPs and PBAT-MPs on peanut and rhizobium symbiosis, and provides new perspectives for legume production and environmental safety.

Unraveling the effects and mechanisms of microplastics on anaerobic fermentation: Exploring microbial communities and metabolic pathways

To investigate the effects of microplastics (MPs) on hydrolysis, acidification and microbial characteristics during waste activated sludge (WAS) anaerobic fermentation process, five different kinds of MPs were added into the WAS fermentation system and results indicated that, compared to the control group, the addition of polyvinyl chloride (PVC)-MPs exhibited the least inhibition on volatile fatty acids (VFAs), reducing them by 13.49 %. Conversely, polyethylene (PE)-MPs resulted in the greatest inhibition, with a reduction of 29.57 %. MPs, while accelerated the dissolution of WAS that evidenced by an increase of lactate dehydrogenase (LDH) release, concurrently inhibited the activities of relevant hydrolytic enzymes (α-Glucosidase, protease). For microbial mechanisms, MPs addition affected the proliferation of key microorganisms (norank_f_Bacteroidetes_vadinHA17, Ottowia, and Propioniclava) and reduced the abundance of genes associated with hydrolysis and acidification (pfkb, gpmI, ilvE, and aces). Additionally, MPs decreased the levels of key hydrolytic and acidogenic enzymes to inhibit hydrolysis and acidification processes. This research provides a basis for understanding and unveils impact mechanisms of the impact of MPs on sludge anaerobic fermentation.

Insights into PVC-promoted hydrothermal carbonization of manure: Dechlorination, inorganic metals removal, and combustion behaviors

Hydrothermal carbonization (HTC) can serve as a promising route to effectively co-valorize biomass and plastic wastes for solid fuel production. However, manure-derived hydrochar for fuel application remains a significant challenge due to its high ash content and low energy density. Polyvinyl chloride (PVC), as a chlorine-containing plastic, subjected to HTC commonly results in the generation of massive acidic wastewater. Herein, we proposed a PVC-promoted HTC route for high energy–density hydrochar production. By utilizing PVC as an in situ acidic additive, the HTC condition was optimized at 275 °C, 30 min, with a PVC addition of 10 %. The hydrochar obtained under the optimized condition exhibited a higher heating value (HHV) of 25.89 MJ/kg, comparable to bituminous coals, and achieve a high energy recovery rate of nearly 70 %. Moreover, the excellent removal efficiencies of inorganic metals and chlorine both exceeding 95 % (except for Fe at 86 %) were observed, owing to the strong interactions between dechlorination and inorganic metals removal. Importantly, it was evidenced that acidic reaction environment was demonstrated to enhance the carbonization degree and modify the hydrochar formation mechanism. Furthermore, the high comprehensive combustion index S of 3.22 × 10−7 %2/( °C3·min2) and low average Ea of 134.20 kJ/mol were achieved, indicating the favorable combustion behaviors. Overall, this work systematically and comprehensively investigated the PVC-promoted HTC of manure waste for advanced solid fuel production and examined its combustion characteristics, unveiling the hydrochar formation mechanism.

Combined effects of micron-sized polyvinyl chloride particles and copper on seed germination of perilla.

Microplastics (MPs) and copper (Cu) pollution coexist widely in cultivation environment. In this paper, polyvinyl chloride (PVC) were used to simulate the MPs exposure environment, and the combined effects of MPs + Cu on the germination of perilla seeds were analyzed. The results showed that low concentrations of Cu promoted seed germination, while medium to high concentrations exhibited inhibition and deteriorated the morphology of germinated seeds. The germination potential, germination index and vitality index of 8mg • L-1 Cu treatment group with were 23.08%, 76.32% and 65.65%, respectively, of the control group. The addition of low concentration PVC increased the above indicators by 1.27, 1.15, and 1.35 times, respectively, while high concentration addition led to a decrease of 65.38%, 82.5%, and 66.44%, respectively. The addition of low concentration PVC reduced the amount of PVC attached to radicle. There was no significant change in germination rate. PVC treatment alone had no significant effect on germination. MPs + Cu inhibited seed germination, which was mainly reflected in the deterioration of seed morphology. Cu significantly enhanced antioxidant enzyme activity, increased reactive oxygen species (ROS) and MDA content. The addition of low concentration PVC enhanced SOD activity, reduced MDA and H2O2 content. The SOD activity of the Cu2+8 + PVC10 group was 4.05 and 1.35 times higher than that of the control group and Cu treatment group at their peak, respectively. At this time, the CAT activity of the Cu2+8 + PVC5000 group increased by 2.66 and 1.42 times, and the H2O2 content was 2.02 times higher than the control. Most of the above indicators reached their peak at 24h. The activity of α-amylase was inhibited by different treatments, but β-amylase activity, starch and soluble sugar content did not change regularly. The research results can provide new ideas for evaluating the impact of MPs + Cu combined pollution on perilla and its potential ecological risk.

Potential valorization and transformation of plastic biomass waste into useful fertilizers in agricultural Mediterranean soils under extreme climate conditions

Plastics are widely used in agricultural practices, although recently they have been recognized as a new emerging risk in soils. Polyethylene (PE), is commonly used by farmers to cover agricultural practices; geotextile, is used mainly for ground and crop covering; and polyvinyl chloride (PVC) is considered the main material contained in irrigation hoses. The present study aimed to assess the effects of three plastics (polyethylene, geotextile, polyvinyl chloride) on the soils’ fertility. Several pot experiments were conducted in soil samples from the study area (Thessaly) contaminated with adequate amounts of each plastic type (PE, geotextile: 2% v/v and PVC: 5% v/v). Water was added in two quantities: one to maintain typical soil moisture levels according to the crops’ requirements and an elevated amount to form supersaturating soil conditions similar to those following a flood event. Furthermore, temperature effect was also investigated to assess its impact on plastics’ behavior and soil fertility. The levels of all nitrogen forms and the microbial activity were determined at 10, 30, and 60 days. Significant changes were observed in the concentrations of nitrate, nitrite, and ammonium ions under ambient soil moisture conditions especially when the microplastics were incubated for a longer period. PE addition resulted in greater changes, followed by geotextile, although PVC addition did not induce significant changes in the nitrification process during the experimental time. PE and geotextile microplastics appeared to enhance microbial colonization and total microbial activity. In addition, soil characteristics were notably altered when moisture stress conditions were reached (85%) and when soils were flooded for two months, leading to a severe decrease in the availability of all nitrogen forms. The results showed that alterations in soil nitrogen forms in the presence of plastics study are crucial for maintaining the health and improving the productivity of Mediterranean soils.

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.

Study on Bitumen Modified with Crumb Rubber and PVC

Abstract: This study investigates the mechanical and rheological properties of bitumen modified with crumb rubber and polyvinyl chloride (PVC). The crumb rubber and PVC were added to bitumen at varying percentages and the resulting modified bitumen was tested for its viscosity, penetration, softening point, and elastic recovery. The results show that the addition of crumb rubber and PVC to bitumen improves its viscosity and elastic recovery properties, while reducing its penetration and softening point. The study also explores the optimal percentage of crumb rubber and PVC for modifying bitumen to achieve the desired mechanical and rheological properties. Overall, the study highlights the potential of using crumb rubber and PVC as sustainable additives for improving the performance of bitumen in road construction.

Synergistic effect and chlorine migration behavior in co-pyrolysis of Pingshuo coal and polyvinyl chloride and directional chlorine enrichment using calcium oxide

Co-pyrolysis of waste plastics and low-rank coal is an important way to realize the recycling of plastic wastes and the clean and efficient conversion of coal. However, halogens released would cause equipment corrosion and affect tar quality when halogenated plastics were co-pyrolyzed with coal. For this reason, polyvinyl chloride (PVC), as a representative of halogenated plastic, was co-pyrolyzed with Pingshuo coal (PS) in a two-stage fixed-bed reactor. The synergistic effect between PS and PVC and the migration behavior of chlorine were investigated, and the in-situ removal of chlorine during pyrolysis was explored by adding a CaO bed in the second stage of the reactor. The results showed that the addition of PVC in PS has a positive synergistic effect on tar yield with a maximum tar yield increment of 2.30 wt% at 30 wt% PVC, which is related to the negative synergistic effect on gas yield. Furthermore, the addition of PVC increases the content of 1–3 ring aromatics and decreases the content of aliphatics in the tar. The chlorine content in char and tar increases significantly with the increase of PVC addition. The addition of a CaO bed can significantly reduce the yield of HCl and the chlorine content in the tar. At 700 ℃, the dehydrochlorination efficiency of CaO can reach 78.1%. However, the CO2 produced by PS pyrolysis will reduce the dehydrochlorination efficiency of CaO, and this effect of CO2 can be reduced by increasing the temperature of the CaO bed.

Polyethylene and polyvinyl chloride microplastics promote soil nitrification and alter the composition of key nitrogen functional bacterial groups

Microplastics (MPs) contamination in soils seriously threatens agroecosystems globally. However, very few studies have been done on the effects of MPs on the soil nitrogen cycle and related functional microorganisms. To assess MP's impact on the soil nitrogen cycle and related functional bacteria, we carried out a one-month soil incubation experiment using typical acidic soil. The soil was amended with alfalfa meal and was spiked with 1% and 5% (mass percentage) of low-density polyethylene (LDPE) and polyvinyl chloride (PVC) MPs. Our results showed that both LDPE and PVC addition significantly increased soil nitrification rate and nitrate reductase activity, which could further promote soil denitrification. The relative abundance of diazotrophs, ammonium oxidizing, and denitrifying bacterial groups were significantly altered with MPs addition. Moreover, the MPs treatments greatly enhanced denitrifying bacteria richness. Redundancy analysis showed that nitrate reductase activity was the most significant factor affecting the soil functional bacterial community. Correlation analysis shows that Nitrosospira genus might be for the improvement of soil nitrification rate. Our results implied that MPs exposure could significantly affect the soil nitrogen cycling in farmland ecosystems by influencing essential nitrogen functional microorganisms and related enzymatic activities.

Microbial resistance in rhizosphere hotspots under biodegradable and conventional microplastic amendment: Community and functional sensitivity

Microplastics (MPs) are ubiquitous in the environment and can potentially damage microbes and plant root cells. Although the influence of MPs on soil parameters has been investigated, the response of microbiomes to soil microenvironments with contrasting limiting factors, particularly in flooded soil environments such as rice paddies, remains unknown. Using zymography and high-throughput sequencing, we conducted a mesocosm experiment with polylactide (PLA) and polyvinyl chloride (PVC) MPs to compare the effects of biodegradable and conventional MPs on rice growth, exoenzyme kinetics, and microbial communities. Both conventional and biodegradable MPs significantly inhibited rice growth, possibly by affecting nutrition. Compared with the control soils, both PLA- and PVC-amended soils exhibited higher enzyme activity in the hotspots. The enzymatic resistance to MPs was higher in ‘coldpots’ with PVC addition compared to that in PLA and control treatments. Bacterial biomass increased but diversity declined in PLA-amended soils, possibly because PLA particles act as carbon input inhabited the population of bacteria. Our findings suggest that co-occurrence networks among bacteria were strengthened by the addition of both MPs, with an increase in microbial functionality resilience and enhanced competition with neighboring roots for nutrient mining. This competition for nutrients may adversely affect plant growth.

Poly Vinyl Chloride Additives and Applications-A Review

A Pure polyvinyl chloride (PVC) is a white, brittle material and it is the third-largest polymers produced after polyethylene and polypropylene as 40 million tons of PVC are produced yearly. The basic structure of PVC is (C2H3Cl)n and it is produced by polymerization of the vinyl chloride monomer (VCM) with a polymerization degree ranges from 300 to 1500. The chlorine content in PVC is about 57% by weight, which makes it less dependent on hydrocarbon content. In this paper, we are going to reveal the PVC additives and applications.

Deciphering the role of microplastic size on anaerobic sludge digestion: Changes of dissolved organic matter, leaching compounds and microbial community

Here the role of microplastic size on dissolved organic matter, leaching compounds and microbial community during anaerobic sludge digestion was evaluated. Compared to that without the addition of polyvinyl chloride (PVC), during the 30 days' incubation, the anaerobic sludge digestion by adding PVC at the size of 75 μm and the concentration of 2.4 g/g volatile solids (VS) showed a 8.5% lower cumulative methane production, while a 17.9% higher cumulative methane production was noted by adding PVC at the size of 3000 μm and the concentration of 2.4 g/g VS. A long-term fed-batch laboratory-scale fermenter test for 147 days further testified, that higher removal efficiencies of total solids, volatile solids, and total chemical oxygen demand, and higher methane production were noted by adding PVC (2.4 g/g VS, 3000 μm) into the fermenter. More interestingly, higher concentrations of proteins, polysaccharides, volatile fatty acids, and soluble microbial by-products component were noted in the liquid phase of sludge drawn from the fermenter added with PVC since the biomass therein showed higher efficiencies of solubilization, hydrolysis, acidification, and methanogenesis. Moreover, as identified from the fermenter added with PVC, dibutyl phthalate (DBP) was the most predominant leaching phthalates compound, although the biomass therein showed a 93.4% anaerobic biodegradability of DBP. The leaching of DBP drove the predominance of microbial community towards Synergistota and Methanosaeta. More irregular elliptical shallow dimples were noted on the PVC surface after 147 days' incubation, accompanied with abundances of Proteobacteria, Actinobacteriota, Chloroflexi, Methanosaeta and Methanobacterium. The results from this study showed that the size of microplastic was a crucial factor in evaluating its impact on anaerobic sludge digestion.

Pyrolysis Characteristics of Hailar Lignite in the Presence of Polyvinyl Chloride: Products Distribution and Chlorine Migration

This study investigated the effects of polyvinyl chloride (PVC) addition on low-rank coal’s pyrolysis characteristics, especially the products distribution and chlorine migration. Hailar lignite (HLE) with different industrial, pure, PVC-content additions were prepared (the mass percentage of PVC addition was from 5% to 25%), and the co-pyrolysis characteristics of HLE and PVC were performed on a fixed-bed reactor and thermogravimetric analyzer. The chars were characterized with X-ray diffraction (XRD), X-ray fluorescence (XRF), and Fourier-transform infrared (FT-IR) spectroscopy analysis. The gas and tar compositions were analyzed by using gas chromatography (GC) and a gas chromatography–mass spectrometry (GC–MS) system, respectively. The results indicate that the addition of PVC can increase the release amounts of CH4, C2H4, and C2H6, simultaneously reducing the release amount of CO2 and CO; the quality of pyrolysis tar was also improved, especially the alkane content in tar, which increased by 6.9%. The migration of chlorine in PVC was analyzed with the different PVC additions and terminal pyrolysis temperatures. It showed that the content of chlorine in the gas phase first increased with the increasing pyrolysis temperature, but at the terminal temperature of 600 °C, the chlorine in the gas phase began to decrease. The results of the co-pyrolysis char characterization show that the content of the alkali metal oxide gradually decreases in the char, and metal chloride appears during the pyrolysis process. In the co-pyrolysis reaction of coal and PVC, chlorine was fixed in the char, thereby reducing the distribution of chlorine in the gas phase. This also proves that the PVC pyrolysis process, with the participation of low-rank coal, can enrich chlorine into the solid phase, thus reducing the emission of chlorine in the gas phase.

Co-pyrolysis of sewage sludge and metal-free/metal-loaded polyvinyl chloride (PVC) microplastics improved biochar properties and reduced environmental risk of heavy metals

Co-pyrolysis of sewage sludge and plastics have been utilized for producing biochars as a strategy to fix plastic pollution. However, comparative studies on the characteristics and environmental risk of heavy metals in biochars obtained by the co-pyrolysis of sludge and microplastic with/without metal additives are seldom. Here we demonstrated the effects of simulated co-pyrolysis (at 400 °C) of sewage sludge and metal-free or metal-loaded polyvinyl chloride (PVC) microplastics at different mass ratios (1:0, 19:1, 3:1, 1:3, sewage sludge: PVC (w/w)) respectively. Results revealed that co-pyrolysis of metal-loaded PVC and sewage sludge resulted in higher electrical conductivity, ash content, and an acidic pH of biochars as compared to the co-pyrolysis of metal-free PVC and sewage sludge. Addition of metal-loaded PVC increased total concentrations of calcium (Ca), magnesium (Mg), cadmium (Cd), and lead (Pb) in biochars, but reduced the bioavailability of Cd, chromium (Cr), nickel (Ni), and zinc (Zn) in biochars. Analysis of chemical speciation showed that heavy metals (except Pb) in biochars derived from co-pyrolysis of sewage sludge and metal-loaded PVC had higher percentage of more stable fraction (residual fraction) and lower potential ecological risk index (RI) value. S1AP3 (sludge: metal-loaded PVC = 1:3) biochar had the lowest environmental risk based on RI value (14.41). To sum up the present study suggests that the addition of metal-loaded PVC microplastic in sewage sludge had a positive impact on the immobilization of heavy metals during co-pyrolysis process.

Investigate the use of recycled polyvinyl chloride (PVC) particles in improving the mechanical properties of stone mastic asphalt (SMA)

Every year, millions of tons of industrial waste and household waste, including plastic waste, cause damage to the environment through landfilling, incineration, or dumping in open water. Polyvinyl chloride (PVC) is one of the most broadly used plastic materials in the modern world today, which can be reused in various industries by recycling waste. This matter can significantly help to improve environmental health. In this study, the impact of two kinds of recycled PVC (recycled water pipes and recycled candy wrappers) with three various percentages (2%, 3.5%, and 5% by weight of bitumen) on improving the mechanical properties of stone mastic asphalt (SMA) mixture has been investigated. For this purpose, in the present research, the Static creep test, Deformation strength test (Kim Test), Skid resistance test, indirect tensile strength (ITS) test, Semi-circular bending (SCB) fracture test, and conventional bitumen tests have been used. The conventional bitumen tests indicated that recycled PVC materials increased the softening point, viscosity, and specific gravity and reduced the penetration and the ductility of bitumen. Also, the results of mechanical tests illustrated that the addition of recycled water pipe particles and recycled candy wrapper particles improved the indirect tensile strength and increased the moisture resistance in stone mastic asphalt. However, increasing the percentage of these recycled materials to the asphalt mix had a negative effect on skid resistance. Regarding these recycled material's effects on rutting resistance, the Kim test depicted that raising the percentage of these recycled additives increases the rutting resistance of asphalt mixtures at high temperatures. Also, the static creep test revealed that the addition of these recycled PVCs reduces the accumulated permanent axial strain and increases the creep stiffness of stone mastic asphalt mixture. Moreover, based on the results of the fracture test, the addition of recycled PVC particles to the stone mastic asphalt mixture has a positive effect on the fracture energy at intermediate temperatures and intensity factor (Keff) at sub-zero temperature. Finally, in a general conclusion, it can be stated that recycled water pipe additive has a more notable influence on the mechanical properties of SMA mixture than recycled candy wrapper additive.

A study of the effectiveness of chemical additives on the characteristic flow of crude oils

This article aims to study the effect of the concentration with additives on the kinematic viscosity of crude oils. Additionally, the influence of solvents that reduces the viscosity of heavy oil with significance to their functions in the flow rate of crude oil, which is transported by conveyor pipes to long distances. Different concentrations of polymers with different types named as Polyvinyl chloride (PVC), Sodium dodecyl sulfate (SDS) and Carboxymethyl cellulose (CMC) were tested in order to analyze the experimental data. The results demonstrate that the impact of the additives to the viscosity and comparing at different temperatures. The data can be used to investigate the types of additives that can increase or reduce the viscosity of crude oils. Furthermore, the outcomes show that the addition of PVC at a concentration of (100ppm) and temperature range (30-50 CO) reduces the viscosity of crude oil to the ultimate value the 12.63% at 30Co. However, the viscosity decreases drastically up to (100ppm), and then the amount of viscosity is increased.

Co-hydrothermal carbonization of sewage sludge and polyvinyl chloride for the production of high-quality solid fuel with low nitrogen content

Sewage sludge (SS) and polyvinyl chloride (PVC) are typical solid wastes. Their co-hydrothermal carbonization behavior was investigated in this study. The low-nitrogen solid fuel (0.94 wt%) with high heating value (9.84 MJ·Kg−1) was prepared through parameter optimization at 240 °C for 1.5 h under water loading amount of 0.84 g·cm−3. In an acidic environment, the stubborn protein in SS could be converted into free amino acids, which were generated by the decomposition of PVC under hydrothermal conditions. The stubborn N could be translated into easy-to-remove N, such as nitrile–N and inorganic N, and the dehydration reaction was evidently promoted. The acidic environment at high temperatures caused the dissolution of ash in SS and improved the combustion performance of hydrochar. FT-IR results showed that, with increased PVC loading proportion, -C=N- was converted into -C=O-. Co-hydrothermal carbonization could effectively improve the combustion performance of hydrochar. The addition of PVC could lead to the generation of increased volatile matter, fixed carbon, and unsaturated CC, and the combustion temperature range shifted to a high range. However, the generation of graphite-like carbon was caused by further increasing the PVC loading proportion, which hindered the improvement of its combustion performance. In the parameter optimization study, the increased water loading amount (from 0.54 g·cm−3 to 0.84 g·cm−3) had the most evident effect on the N content in the hydrochar (from 1.50 wt% to 0.94 wt%), which promoted the denitrification efficiency (from 60.11% to 75.00%) and the conversion of -C=N- components, and prevented further polymerization of solid products.

Co-hydrothermal carbonization of sewage sludge and polyvinyl chloride: Hydrochar properties and fate of chlorine and heavy metals

An efficient method of synergetic dechlorination and reduction of heavy metals risk is crucial for the clean resource utilization of sewage sludge (SS) and polyvinyl chloride (PVC). In this work, SS was upgraded to hydrochar using co-hydrothermal carbonization (HTC) with PVC at different mixing ratio (30─70%) at 230 °C. Transformation behaviors of chlorine and heavy metals in hydrochars, along with fuel properties, were evaluated. The results illustrated that Mn and Zn could be effectively removed during co-HTC and low ratio addition of PVC was beneficial for reducing the toxicity of Ni and As. Meanwhile, compared with the HTC of single PVC, co-HTC with SS could further improve the dechlorination efficiency (69.49─81.35%). Particularly, the blending ratio of SS to PVC at 7:3 showed high fuel ratio and HHV (13.58MJ/kg) with desirable combustion performance. These findings offered a potential approach to convert SS and PVC into clean solid fuel.

Hydrogen-rich gas production from hydrochar derived from hydrothermal carbonization of PVC and alkali coal

This work targets to produce hydrogen-rich syngas by steam gasification of hydrochars obtained from co-hydrothermal carbonization (co-HTC) of polyvinyl chloride (PVC) and alkali coal. Hydrochar properties were assessed in terms of ultimate analysis, proximate analysis and the content of typical elements. The syngas, tar and char properties were investigated to explore the steam gasification performace of hydrochars. The co-HTC facilitated the destruction of the hydrophilic groups based on the O/C atomic ratio. The co-HTC increased the yield of H2 and CH4, while the CO2 yield was concurrently reduced. A relative high H2/CO ratio of around 1.65–3.96 was achieved when gasified hydrochar under the various temperature. This temperature was supposed to be an acceptable operational window for yielding H2-rich syngas. The catalytic effect of alkali and alkaline earth metals (AAEMs) on H2 production was weakened due to the AEEMs removal during the co-HTC, while the H2 production could be remedied by the PVC addition. The evolution of poly-aromatic hydrocarbons (PAHs) convinced the event of primary or secondary tars transformed into the tertiary tar. The rich pore structure of char indicated that char have good potential in adsorption, and the adsorption experiment of malachite green confirmed this point of view.These findings will offer comprehensive data on the coal upgrading and hydrochar gasification.