Pyrolysis Products Research Articles

Biofilm mitigation in hybrid chemical-biological upcycling of waste polymers.

Introduction: Accumulation of plastic waste in the environment is a serious global issue. To deal with this, there is a need for improved and more efficient methods for plastic waste recycling. One approach is to depolymerize plastic using pyrolysis or chemical deconstruction followed by microbial-upcycling of the monomers into more valuable products. Microbial consortia may be able to increase stability in response to process perturbations and adapt to diverse carbon sources, but may be more likely to form biofilms that foul process equipment, increasing the challenge of harvesting the cell biomass. Methods: To better understand the relationship between bioprocess conditions, biofilm formation, and ecology within the bioreactor, in this study a previously-enriched microbial consortium (LS1_Calumet) was grown on (1) ammonium hydroxide-depolymerized polyethylene terephthalate (PET) monomers and (2) the pyrolysis products of polyethylene (PE) and polypropylene (PP). Bioreactor temperature, pH, agitation speed, and aeration were varied to determine the conditions that led to the highest production of planktonic biomass and minimal formation of biofilm. The community makeup and diversity in the planktonic and biofilm states were evaluated using 16S rRNA gene amplicon sequencing. Results: Results showed that there was very little microbial growth on the liquid product from pyrolysis under all fermentation conditions. When grown on the chemically-deconstructed PET the highest cell density (0.69g/L) with minimal biofilm formation was produced at 30°C, pH 7, 100rpm agitation, and 10sL/hr airflow. Results from 16S rRNAsequencing showed that the planktonic phase had higher observed diversity than the biofilm, and that Rhodococcus, Paracoccus, and Chelatococcus were the most abundant genera for all process conditions. Biofilm formation by Rhodococcus sp. And Paracoccus sp. Isolates was typically lower than the full microbial community and varied based on the carbon source. Discussion: Ultimately, the results indicate that biofilm formation within the bioreactor can be significantly reduced by optimizing process conditions and using pure cultures or a less diverse community, while maintaining high biomass productivity. The results of this study provide insight into methods for upcycling plastic waste and how process conditions can be used to control the formation of biofilm in bioreactors.

Recovering high-quality glass fibers from end-of-life wind turbine blades through swelling-assisted low-temperature pyrolysis

The recycling of end-of-life wind turbine blades has become a global environmental challenge driven by the rapid growth of wind power. Pyrolysis is a promising method for recovering glass fibers from these discarded blades, but traditional pyrolysis is often operated at high temperatures, which degrades the mechanical properties of recovered fibers. To address this issue, a swelling-assisted pyrolysis method was proposed to recover high-quality glass fibers from end-of-life wind turbine blades at low temperatures. The results confirmed that the decomposition of the resin matrix within the blade was significantly promoted at low temperatures in the swelling-assisted pyrolysis process, achieving a resin decomposition ratio of 76.8 % at 350 °C. This improvement was attributed to enhanced heat transfer and co-pyrolysis with acetic acid. Swelling could physically disrupt the cross-linked structure of the blade, creating a more porous and layered structure, thereby enhancing heat transfer during the pyrolysis process. Simultaneously, the co-pyrolysis with acetic acid could generate hydrogen radicals, which promoted the cracking of macromolecular oligomers into lighter products or gaseous alkanes. Consequently, the formation of pyrolysis char within the solid pyrolysis product was reduced, shortening the oxidation duration to 30 min. In comparison to traditional pyrolysis, the swelling-assisted pyrolysis process effectively suppressed the diffusion of surface defects over the recovered fibers, leading to promising improvements in their flexibility, elasticity, and mechanical properties, with tensile strength notably increased by 27.5 %. These findings provided valuable insights into recovering high-quality glass fibers from end-of-life wind turbine blades.

Pyrolytic Decomposition of Polyethylene in the Presence of Aluminosilicate Materials Containing Nickel Oxide

The work is devoted to the study of the pyrolysis of high-density polyethylene (PE) in the presence of aluminosilicate materials containing nickel oxide. The process of catalytic pyrolysis of plastics makes it possible to convert polymers into chemical compounds, which can later be used as an additional source of fuels, raw materials for the chemical industry or polymer production. The physicochemical parameters of materials containing nickel oxide have been established using the following methods: IR-Fourier spectroscopy; x-ray diffraction analysis; N2 physical adsorption method; thermogravimetric analysis; pyrolytic gas chromatography. The dependences of the chemical composition of PE pyrolysis products on the type of support used and the presence of nickel oxide. The presence of nickel oxide in the studied aluminosilicates increases the Lewis acidity, which increases the content of aromatic compounds in the pyrolysis products. The activation energy of the PE pyrolysis process in the presence of MCM-41 containing nickel oxide was calculated from experimental data.

Synergistic Interaction during Copyrolysis of Soybean Straw and Tire Waste: Improving Emissions and Product Quality.

This study explores copyrolysis of soybean straw (SS) with hydrogen-rich tire waste (TW) to enhance pyrolytic product quality and reduce pollutant emissions. Addition of TW increased SS biomass conversion from 67.19 to 72.46% and decreased coke/residue formation from 32.81 to 27.54%. The activation energy dropped to 121.84 kJ/mol from 160.73 kJ/mol (as calculated by the Kissinger-Akahira-Sunose method) and 122.78 kJ/mol from 159.76 kJ/mol (as calculated by the Ozawa-Flynn-Wall method). Thermogravimetric analysis coupled with Fourier-transform infrared spectroscopy (TG-FTIR) showed lowered CO2, NO2, and SO2 emissions (5.58, 5.72, 3.38) compared to conventional SS pyrolysis (18.38, 11.55, 12.37). Yields of value-added chemicals (phenols, olefins, aromatics) increased (32.38, 22.17, 30.18%) versus conventional SS pyrolysis (23.56, 13.78, 20.36%). Pyrolysis gas chromatography-mass spectrometry (Py/GC-MS) analysis reveals that the addition of TW leads to a decrease in the production of oxygenates and polycyclic aromatic hydrocarbons, reducing their yields to 8.96 and 7.67%, respectively, down from 19.37 and 14.37%. Simultaneously, it enhances the yields of olefins, aromatics, phenols, and aliphatic hydrocarbons to 23.38, 26.78, 26.17, and 25.78%, respectively, compared to 15.37%, 15.29, 18.36, and 17.25%, respectively, in the absence of TW. In summary, copyrolysis of TW with SS improves product quality and reduces pollutant emissions, marking a significant research contribution.

Selective recovery of pyrolyzates of biodegradable (PLA, PHBH) and common plastics (HDPE, PP, PS) during co-pyrolysis under slow heating

Pyrolytic synergistic interactions, in which the production of pyrolyzates is enhanced or inhibited, commonly occur during the co-pyrolysis of different polymeric materials, such as plastics and biomass. Although these interactions can increase the yield of desired pyrolysis products under controlled degradation conditions, the desired compounds must be separated from complex pyrolyzates and further purified. To balance these dual effects, this study was aimed at examining pyrolytic synergistic interactions during slow heating co-pyrolysis of biodegradable plastics including polylactic acid (PLA) and poly(3-hydroxybutyrate-co-3-hydroxyhexaoate) (PHBH) and petroleum-based plastics including high-density polyethylene (HDPE), polypropylene (PP), and polystyrene (PS). Comprehensive investigations based on thermogravimetric analysis, pyrolysis–gas chromatography/mass spectrometry, and evolved gas analysis-mass spectrometry revealed that PLA and PHBH decompose at lower temperatures (273–378 °C) than HDPE, PP, and PS (386–499 °C), with each polymer undergoing independent decomposition without any pyrolytic interactions. Thus, the independent pyrolysis of biodegradable plastics, such as PLA and PHBH, with common plastics, such as HDPE, PP, and PS, can theoretically be realized through temperature control, enabling the selective recovery of their pyrolyzates in different temperature ranges. Thus, pyrolytic approaches can facilitate the treatment of mixed biodegradable and common plastics.

Synthesis and Flame Retardant Behavior of Phosphorous- and Nitrogen-Containing Copolymer and Its Application in Polypropylene.

In this study, a 4-(hydroxymethyl)-2,6,7-trioxa-1-phosphabicyclo[2.2.2]octane 1-oxide (PEPA)-functionalized acrylate monomer, PEPAA, is designed and utilized for the synthesis of macromolecular flame retardants poly(PEPAA-co-AM) with varying PEPAA/AM ratio through copolymerization with acrylamide (AM). The poly(PEPAA-co-AM) is then incorporated into polypropylene (PP) to prepare PP/poly(PEPAA-co-AM) composites. The flame retardant effect of poly(PEPAA-co-AM) on PP is investigated using cone calorimetric test (CCT), and compared with that of PEPAA homopolymer (P-PEPAA), AM homopolymer (PAM), and blends of P-PEPAA/PAM. The results demonstrate that, in comparison with P-PEPAA, PAM, and blends of P-PEPAA/PAM, the incorporation of poly(PEPAA-co-AM) significantly enhances the flame retardancy of PP. Notably, the best flame retardancy is achieved when the ratio of PEPAA/AM copolymerization in poly(PEPAA-co-AM) is 2/8. The morphology and composition of residual chars from combustion are analyzed using SEM-EDS while the residual graphitization degree is examined through Raman spectroscopy. Additionally, TG-FTIR-MS is utilized to investigate the pyrolysis products in gas phase during thermal decomposition of poly(PEPAA-co-AM). Based on these experimental results, a flame retardant mechanism for poly(PEPAA-co-AM) is proposed. The PP/poly(PEPAA-co-AM) composites not only retain the excellent processing properties of pure PP but also exhibit enhanced mechanical properties.

Integrating solar-driven biomass gasification and PV-electrolysis for sustainable fuel production: Thermodynamic performance, economic assessment, and CO2 emission analysis

Biomass gasification provides a promising pathway for sustainable fuel production. Nevertheless, its development is hindered by lower efficiencies in biomass–to–fuel energy conversion and carbon utilization, along with restricted scale due to economic collection radius. To tackle these challenges, a solar–biomass hybrid gasification system is proposed for sustainable fuel production. The system employs parabolic trough and tower concentrators to generate solar heat, driving the biomass pyrolysis and pyrolysis products gasification reactions to produce bio–solar syngas. The high–density bio–oil and char produced in distributed pyrolysis units can be economically transported to the centralized gasification plant. Moreover, PV–electrolysis water is utilized to generate H2 and O2, which are used to adjust syngas composition and substitute for air separation O2, respectively. Consequently, the energy consumption for water–gas shift, CO2 separation, and air separation units can be reduced. Thermodynamic, economic, and CO2 emission performance are analyzed for a typical case of methanol production using corn residue. The total energy conversion efficiency of the hybrid system can reach 65.01 %, representing an improvement of 6.57 % compared to the conventional biomass gasification system. The fuel production cost is estimated to be $354.1 per ton, falling within the market price range. Additionally, the greenhouse gas emissions to produce unit kg methanol can be reduced by 0.63 kg CO2eq. Furthermore, we analyzed the performance of six representative fuel production scenarios involving different types of biomass feedstocks. Finally, the limitations of this work and the feasibility of its practical applications are discussed. This study offers an innovative approach to bio-solar fuel production, promoting the development of circular bio-economy and the application of sustainable fuel.

Investigation on NO and N2O emissions characteristics in deep peak regulation circulating fluidized bed boilers

Abstract To adapt to the increasing proportion of new energy power generation capacity, coal power must transition from its traditional role as the primary power source to serving as a fundamental backup and system regulation energy source. The circulating fluidized bed technology is known for its wide range of load regulation capabilities; however, emissions of pollutants during load regulation can exhibit significant variability. This study utilized Aspen Plus software to develop a circulating fluidized bed combustion model based on a gas-solid fluid dynamics model, an equivalent coal pyrolysis model, and a multi-phase macroscopic combustion reaction dynamics model of pyrolysis products. This model was used to predict both the temperature distribution within the furnace chamber and the distribution of pollutant concentrations. Predictions of pollutant emissions from 100 % load to 30 % load of the circulating fluidized bed were explored under the original combustion condition and 5 % proportion of recirculated flue gas. Under the primary combustion condition, the emission concentration of NO x showed a decreasing and then increasing trend with decreasing load, while the concentration of nitrous oxide, in contrast to NO x , showed an increasing and then decreasing trend. The effect of recirculated flue gas on pollutant emissions was not significant at reduced loads. This study aims to provide technical support and theoretical guidance for the management of pollutant emissions from the deep peak regulation of actual circulating fluidized beds.

Quantitation of polystyrene by pyrolysis-GC-MS: The impact of polymer standards on micro and nanoplastic analysis

The analytical method for detecting and quantifying micro and nanoplastics (MNPs) using Pyrolysis-Gas Chromatography-Mass Spectrometry (Py-GC-MS) is evolving and continuously refined. The requirement for accurate analytical methods faces challenges during method validation due to the scarcity of relevant reference materials. Additionally, the wide array of polymer types and their diverse characteristics further complicate this validation process. This study evaluated the impact of using diverse polystyrene (PS) standards with different molecular weights, polydispersity indexes, tacticity, endcapping, and chain branching, on quantifying the mass concentration of PS in various products. The results for the PS-based products showed inconsistencies across different standards, indicating that the measurements for a single product varied substantially when different polystyrene (PS) standards were applied. The influence of sample quantity on pyrolysis revealed differences in the ratios of pyrolysis products among various PS standards and different sample amounts. This research emphasizes the complexities involved in the precise quantification of polymers using Py-GC-MS. It provides valuable insights crucial for quantitative MNP analysis, highlighting the need for refined calibration strategies and standardised reference materials to improve the reliability of the MNP analysis method.

Investigating the adsorption mechanism of zinc chloride-modified porous carbon for sulfadiazine removal from water

Abstract Sulfadiazine (SDZ) is a commonly used antibiotic in medicine, aquaculture, and animal husbandry. However, its misuse has resulted in its release into soil and water environments, posing a gradual threat to the environment and human health. In this study, cotton pulp, poplar sawdust, and corn stover were chosen as raw materials. Zinc chloride (ZnCl2) was used as a modifier to prepare modified porous carbon through pyrolysis at different carbonization temperatures (400 and 800°C). The objective was to investigate the adsorption effect and mechanism of modified porous carbon on SDZ in aqueous environments, as well as the effect of different biomass fractions of the carbon source on the adsorption effect. The physical and chemical properties of the modified porous carbon were characterized by various means of characterization, and the results showed that the high temperature and modification effects made the adsorbent material possess a larger specific surface area and richer pore structure, higher aromaticity, higher degree of graphitization, etc., which would be beneficial for the adsorption of SDZ. Among them, CCPZ800 showed the highest saturation adsorption of SDZ, Q max = 425.45 mg/g. The adsorption experiments were carried out by changing the initial conditions and fitted with kinetic and isothermal adsorption to further explain the adsorption mechanism of modified porous carbon on SDZ in conjunction with the adsorption of SDZ by hydrothermal carbon materials. The results showed that the adsorption of modified porous carbon on SDZ conformed to the quasi-secondary kinetic and Freundlich isothermal adsorption models. Adsorption mechanism of SDZ on modified porous carbon followed a multimolecular layer adsorption, with chemical adsorption being the dominant process. Both physical adsorption and chemical adsorption occurred simultaneously, with the main adsorption mechanism being π–π conjugation. In addition, compositional distribution of biomass from different carbon sources results in variations in pyrolysis mode and pyrolysis products, which in turn affect adsorption. By analyzing the effect of variability in the composition of biomass on the adsorption effect of SDZ, it can be concluded that higher cellulose content in the carbon source leads to a better adsorption effect of SDZ. The study showcases the effectiveness of ZnCl2-modified porous carbon in removing SDZ from water, offering insights into the selection of raw materials for this adsorbent preparation.

A novel chemical pre-pyrolysis treatment of waste tyre crumbs: A viable way for low temperature waste tyre pyrolysis

Pyrolysis of tyres is a process that consumes non-renewable energy resources, and is characterised by the requirement of a significant amount of energy. For example, natural rubber and styrene-butadiene rubber require 300–350 °C and 400–450 °C, respectively, to decompose under inert nitrogen conditions. The current study aims, firstly, to reduce the temperature typically used for waste tyre crumbs pyrolysis to minimise the energy requirement of the process as well as to improve the quality of the liquid fraction of the pyrolysis product, tyre derived oil (TDO). Before pyrolysis, waste tyre crumbs were first treated with a mixture of chemicals, dried and then pyrolysed using a 40 g vertical fixed bed reactor. The results acquired from the ultimate analyser for the CHNS illustrated a decrease in carbon from 80.6 % to 57.2 % and an increment in nitrogen (from 0.4 % to 6.5 %) and oxygen (from 9.7 % to 30.2 %) in the treated tyre crumbs. FTIR results indicated that oxidation took place in the treated sample by displaying the presence of oxygenated functional groups in the spectrum, which agreed with CHNS results. The temperature was reduced drastically from a minimum of 400 °C to a minimum of 100 °C for pyrolysis, and therefore, resulting in a lower initial/starting pyrolysis temperature range of 100–115 °C. In addition, approximately 87 wt% pyrolysis yield was obtained out of 60 % pyrolysable substances in a tyre at the final temperature of 280 °C. The differential thermogravimetric analyser (DTA) was used to confirm the extent to which pyrolysis experiments took place in the feedstock by analysing the char after pyrolysis. The current study is set to improve the pyrolysis of waste tyre crumbs by significantly reducing the temperature and time of the process, which lowers the operation cost required for the tyre crumbs’ pyrolysis process.

Study of products derived from the microwave-assisted thermal degradation of high-moor peat

Peat reserves are of great interest for various industries (energy, fuel, chemical, etc.). It is common practice to use pyrolysis to process such solid carbon-containing resources with the subsequent yield of fuel and valuable products. One of the environmentally and energetically favorable ways to degrade carbon-containing feedstock that is currently under development is microwave-assisted pyrolysis. Microwave radiation provides volumetric heating of the material, which significantly increases heating uniformity across the volume of the irradiated sample, providing greater efficiency of heat transfer and avoiding local overheating on the reactor surface. In the conducted study, a system was designed for the microwave processing of organic materials. The structural elements of the system are described, and a schematic showing pyrolysis product separation is presented. A prototype of the developed reactor was used to conduct experiments on degrading high-moor sphagnum peat of the Greko-Ushakovskoe deposit under mild pyrolysis conditions induced by microwave radiation. The component composition of reaction products was analyzed via chromatography-mass spectrometry and compared with the results of previous experiments using conventional thermal pyrolysis. More advanced processing of peat is performed under the conditions of microwave-assisted mild pyrolysis with a high yield of valuable products due to a more efficient heat transfer, uniform heating of the material, and the optimal reaction rate. The developed technology is shown to produce raw materials for a wide range of high-tech industrial productions. The prospects for the industrial use of the proposed microwave-assisted peat processing technology are discussed, specifically for the production of efficient hydrophobic sorbent.

Nitrile Imine Cyclizations and Rearrangements: N-Phenyl-C-styrylnitrile Imine and N-Phenyl-C-phenylethynylnitrile Imine.

The formation and rearrangements of nitrile imines are of ongoing synthetic and theoretical interest. In this paper, we report a computational investigation at the M06/6-311 + G(d,p) level of the formation and rearrangement of propargylic N-phenyl-C-styrylnitrile imine 3 from 2-phenyl-5-styryltetrazole 1 by flash vacuum pyrolysis (FVP). Nitrile imine 3 cyclizes to 3aH-3-styrylindazole 4, which is also generated by H-shifts in the FVP of 3-styrylindazole 8. Tautomerization of 4 and N2-elimination afford cyclohexadienylidene 14, which by cyclization followed by H-shifts yields the primary pyrolysis product, 3-phenylindene 5. An alternate path via 7aH-3-styrylindazole, phenyl(styryl)diazomethane, and phenyl(styryl)carbene is potentially possible. The analogous pyrolysis of 2-phenyl-5-phenylethynyltetrazole 1' afforded cyclopenta[fg]fluorene and cyclopenta[def]phenanthrene via N-phenyl-C-phenylethynylnitrile imine 3' and 3aH-3-phenylethynylindazole 4'. In both cases, 3 and 3', rearrangement to diazocyclohexadienes and cyclohexadienylidenes (e.g., 14) is energetically preferred over alternate aryldiazomethane and arylcarbene intermediates.

Synergistic enhancement of nitrogenous compounds in bio-oils: Hydrogen peroxide pretreatment and nitrogen-rich pyrolysis

A novel pretreatment method, combining H2O2 and nitrogen-rich pyrolysis for biomass was proposed to address the issue of low nitrogen compounds or levoglucosan content in pyrolysis bio-oil. Bio-oil enriched with high content of levoglucosan and nitrogenous compounds was obtained. In this study, the effects of pretreatment conditions (H2O2 solution concentration, pretreatment time, solution pH) and nitrogen-rich ratio on the pyrolysis characteristics of corn stover were investigated. The difficulty of converting different components into nitrogenous compounds was evaluated for the first time. The results reveal that H2O2 pretreatment effectively removed most lignin and ash, leading to a substantial enrichment of cellulose. Notably, carbohydrate content in bio-oil increased by more than 970 %. However, excessive pyrolysis temperature and pH of H2O2 solution can aggravate the decomposition of carbohydrates. The co-pyrolysis of the pretreated corn stover with urea increased the bio-oil yield (up to 56.32 wt%) and the content of nitrogenous compounds (43.16 wt%). The order of ease in converting certain components into nitrogenous compounds is Ketones > Aldehyde > Furans > Phenols > Esters > Alcohols. This study not only clarified the correlation coupling mechanisms between raw material pretreatment conditions and nitrogen-rich ratio with pyrolysis product characteristics. It can also provide guidance for biorefining. Based on the excellent lignin removal effect of the method proposed in this study, it has broad application prospects in the field of biorefinery of lignocellulosic biomass.

Microwave Pyrolysis of Automotive Polypropylene Based on a Microwave Atmosphere Tube Furnace

Plastics have light weight and excellent performance, which are widely used in all kinds of automobiles. Polypropylene (PP) and its reinforcing materials are used in automotive components, where the surfaces of bumpers and fenders are coated with paint. Traditional recycling can frequently generate various pollutants, such as paint sludge. Microwave pyrolysis is a more environmentally friendly pyrolysis method with a higher heating coefficient than traditional electric pyrolysis. This study first explores the elemental composition of two types of automotive PP plastics and uses thermo-gravimetric analysis and the Kissinger-Akahira-Sunose method to preliminarily calculate the activation energy of automotive PP. The calculation results show that the activation energy of PP containing paint ranges from 189.145 kJ/mol- 199.513 kJ/mol, with an average value of 193.903 kJ/mol. The activation energy of PP without paint is between 215.506 kJ/mol-265.794 kJ/mol, with an average value of 242.425kJ/mol. Then, pyrolysis experiments on PP for vehicles without paint are conducted using a microwave atmosphere tube furnace at different temperatures and microwave powers. The experimental results showed that, when the pyrolysis temperature increased from 500oC to 620 oC, the total proportion of gas products rose from 0.75 wt.% to 4.81 wt.%, and the content of alkanes in the liquid products improved from 26.21 wt.% to 34.37 wt.%; when the microwave power increased from 900 W to 1100 W, the gas product rose to 20.77 wt.%, and the content of aromatic compounds in the liquid product improved to 17.78 wt.%. In addition, the pyrolysis experiment of automotive PP containing paint showed that paint had a relatively minor effect on the pyrolysis products of automotive PP. This study shows that using microwave pyrolysis to treat automotive PP and PP with paint is feasible, which provides a reference for the clean treatment of automotive polymers.

Effect of polyethylene terephthalate plastics on nitrogen, sulphur and chlorine contaminants via sludge pyrolysis and Pb/Cu adsorption properties of biochar

ABSTRACT Pyrolysis is an effective process for disposing of municipal sewage sludge (SS). Plastics can affect the SS pyrolysis behaviour and pyrolysis products due to their low ash and high hydrocarbon ratio. The secondary pollutants from the pyrolysis process may also be affected. Therefore, polyethylene terephthalate (PET), a typical plastic, was chosen to investigate the release characteristics of pollutants containing nitrogen, sulphur, and chlorine via SS pyrolysis, and the changes of biochar to adsorb two typical heavy metals, Pb and Cu. The pyrolysis of PET plastics facilitates the migration of N toward solid and liquid-phase products, S and Cl to the gas-phase products via pyrolysis. Oxygenated compounds of pyrolytic volatiles decreased from 38.18% to 28.43%, concurrently promoting the formation of phenolic compounds. The co-pyrolysis improved the quality of biochar and the ability to adsorb Pb and Cu. This systematic study can provide some support for the further improvement of SS pyrolysis technology, and will also be beneficial for subsequent applications.

Kinetic insights and pollution mitigation in waste tire pyrolysis: Targeting sulfur, nitrogen, and PAHs emissions

Waste tires have potential to be used for generation of fuel via thermal degradation because of their non-biodegradable nature. Nevertheless, the formation of various pollutants such as sulfur-based and nitrogen-based are inevitable due to presence of nitrogen and sulfur containing compounds during waste tires production. The main purpose was to examine the effect of variating heating rates on pollutants release because heating rate is an important parameter which influences the pollutants releasing profile. Moreover, Ar and CO2 as reaction medium were used to identify their behavior for restraining the PAHs in gas phase. The present study investigates the influence of heating rates and carrier gas environment (Argon and CO2) to reduce the pollutants emission. Thermogravimetry-Mass Spectrum coupled with Fourier transform infrared spectrometer was used to evaluate the thermal degradation and pollutants formation. The major degradation of waste tires occurred between 300 and 500 ℃. The sulfur-based (H2S, CS2, COS, SO2, and CH3SH), nitrogen-based (NH3, HNCO, NO, and HCN) and 9 series of PAHs pollutants were detected. The higher heating rates promoted the pollutants emission. The degradation of compounds having sulfur content formed -SH radials and -SH helped in further release of sulfur based-pollutants. The NH3 releasing profile started after 200 ℃ and released till around 800 ℃ for 30 ⁰C/min and 40 ⁰C/min but its emission was very low after 600 ⁰C for heating rates 5 ⁰C/min, 10 ⁰C/min, and 20 ⁰C/min. The aromatic compounds fraction was more at higher heating rate due to short residence time for pyrolytic products to go through secondary reaction. The 5 ℃/min and 10 ℃/min were considered favorable heating rates in terms of achieving lowest activation energy in both gas environments. The thermodynamic parameters analysis suggested that waste tires pyrolysis was non-spontaneous and endothermic reaction as well as feedstocks showed potential to be utilized for waste conversion.

Preliminary strategy and product analysis of microwave pyrolysis of waste printed circuit board

AbstractIn this study, microwave pyrolysis of waste printed circuit boards (WPCBs) was carried out in an inert atmosphere, and the effects of pyrolysis temperature and nitrogen flow rate on the yield and composition of pyrolysis products were investigated. With the increase of pyrolysis temperature, the yield of liquid product increases gradually, and the yield of solid product decreases gradually. At 600°C, the yield of each phase tends to be stable. When the temperature continues to rise, the content of H2 and CO decreases, and the content of C6 ~ C9 in the liquid product decreases. Microwave heating promotes the pyrolysis of brominated epoxy resin, which helps to improve the recovery rate of valuable substances and reduce the environmental impact of waste treatment. This study demonstrates that the microwave pyrolysis of WPCBs in nitrogen atmosphere has great potential in the green recovery process.

Alternative green application areas for olive pomace catalytic pyrolysis biochar obtained via marble sludge catalyst

Evaluating industrial wastes in the system with minimum preprocessing and generation economically valuable products from them have critical importance. In this regard, especially cheap, wieldy, and readily available catalysts have been researched to increase variety of useful products in pyrolysis systems, to reduce process time, and to increase quality and diversity of products. Therefore, in this study, marble sludge (named K1) was evaluated as catalyst at different dosages (10%, 20%, 30%, 50%) and pyrolysis temperatures (300, 500, 700 °C) in olive pomace (OP) pyrolysis and; the potential green applications of produced new biochars at new usage areas with different purposes based on characteristics were investigated. ANOVA test results showed that temperature and catalysts ratio had significant effect on pyrolysis product yields since significance value for K1 and temperature was lower than 0.05 for pyrolysis products. OP-K1 biochars had alkaline properties and high earth metal quantities. Moreover, increment in K1 ratio and temperature resulted in decrement of the biochar surface acidity. Therefore, it can be indicated that these biochars can have a potential usage for anaerobic digestion processes, lithium-ion batteries, and direct carbon solid oxide fuel cell (DC-SOFC) but further electrochemical property test should be performed. Moreover, produced biochars can be alternative fuels in some processes instead of coal since they have low S content and high heat values. Consequently, it is foreseen that produced biochars will have an important place in the development of potential usage areas with a new and environmentally friendly approach in different areas apart from the conventional uses of catalytic pyrolysis chars.Graphical abstract

Bio-oil production from the catalytic pyrolysis of raw and torrefied corn waste by using MgO and CaO catalysts

Abstract This research investigates the influence of torrefaction and catalytic pyrolysis of raw corn waste (RCW) to upgrade the quality of bio-oil. RCW was torrefied at 280°C for 16 mins to produce torrefied corn waste (TCW). Natural basic oxides (CaO and MgO) catalysts were selected because of inexpensive and high catalytic performance. Pyrolysis experiments were conducted in a bench-scaled bubbling fluidized bed reactor at 500°C. The effects of torrefaction and the presence of a catalyst on the pyrolysis product both yield and composition were investigated. The results from non-catalytic pyrolysis revealed that TCW pyrolysis gave 15 wt.% lower in oil yield, and about 6.8 wt.% lower in gas yield but the char yield was approximately 22 wt.% higher compared to the pyrolysis of RCW. Considering the effect of catalyst, the yield of bio-oil reduced slightly, while the yield of char and gas increased compared to non-catalytic pyrolysis for both RCW and TCW. The bio-oil composition derived from TCW pyrolysis contained more phenolic and aromatic compounds and significantly lower oxygenated compounds when compared to that of RCW pyrolysis. Moreover, with the presence of the catalysts, the bio-oil composition and HHVs of bio-oil was also improved.