Pyrolytic Transformation Research Articles

Design and Development of g-C3N4/ZnO/CdS Ternary Photocatalyst for the Removal of Environmentally Hazardous Organic Dyes under Visible Light

The processing of wastewater has emerged as a primary focus of research owing to the unavailability of clean water to satisfy the current population’s needs. In this work, a ternary nano-photocatalyst, g-C3N4/ZnO/CdS exhibiting visible light activity has been fabricated via a dual-step process that involved a pyrolytic transformation of urea to g-C3N4 subsequently followed by the solid state mechanochemical method to fabricate g-C3N4/ZnO/CdS. The synthesized nanomaterial underwent characterization using advanced techniques such as XRD, FTIR, FE-SEM/EDAX and UV-DRS techniques. The decomposition of Indigo Carmine dye was performed under the illumination of visible light, resulting in 99.6% degradation using a 50-mg photocatalytic dosage. Kinetic studies indicate that the photodegradation process followed pseudo-first-order where the phenomenon of adsorption adhered to the Langmuir–Hinshelwood model. This work attempted the generation of a multi pathway of electron migration by combining more than one Type-II heterojunction, which can effectively delay the electron-carrier recombination.

The coupling transformation process of biodegradation and pyrolysis for Dananhu low-rank coal

The study presented a novel approach for coupling biodegradation and pyrolysis to transform low-rank coal. In the first stage, four kinds of bacteria, Planomicrobium huatugouensis (P. huatugouensis), Sphingomonas polyaromaticivorans (S. polyaromaticivorans), Pseudomonas putida (P. putida), and Bacillus subtilis subsp. subtilis (B. subtilis subsp. subtilis), were used to transform the Dananhu low-rank coal. After the first stage, the coal that has not been biodegraded (residual coal) undergoes the second stage of pyrolytic transformation, which is carried out by a thermogravimetric analyzer combined with Fourier-transform infrared spectrometry (TG-FTIR). The results showed that the maximum coupling transformation rate of biodegradation and pyrolysis could reach 73.95%, which was 21.88% higher than the thermal transformation rate of Dananhu low-rank coal and 27.37% higher than the optimal microbial transformation rate. This indicated that coupling transformation could significantly improve the utilization rate of Dananhu low-rank coal. In the stage of biodegradation transformation, bacteria destroyed the carboxyl groups, ether bonds, and other oxygen-containing functional groups in Dananhu low-rank coal, converting the large molecules of coal into liquid molecules, meanwhile, the compact coal structure became loose, and the residual coal was also pyrolyzed easily than Dananhu low-rank coal. During the pyrolysis process, a large number of fatty chains, carboxyl groups, oxy groups, and hydroxy groups were decomposed to produce lots of gas-phase products. The pyrolysis products showed an increase in the release of CO and CH4, and an increase in the proportion of aliphatic hydrocarbons in the volatiles. The high efficiency of coupling transformation is due to the combination of the advantages of the two technologies, which is achieving the green and energy-efficient utilization of low-rank coal.

Calcium enhances phosphorus reclamation during biochar formation: Mechanisms and potential application as a phosphorus fertilizer in a paddy soil

Transformation of phosphorus (P) species during pyrolytic production of biochar from P-rich biowastes with a subsequent soil amendment is important to P reclamation. Aiming at increasing the content of plant-available P and restraining the formation of easily mobile P in pyrolysis product, this study used exogenous calcium ions (20 wt% CaCl2) addition prior to pyrolysis to regulate the pyrolytic transformation of P chemical fractions from sewage sludge and bone dreg. Results showed that active Ca catalyzed the decomposition of organic P to transform into inorganic orthophosphate. Based on Hedley’s sequential extraction method, this study found that addition of Ca ions remarkably reduced the content of soluble P, exchange P, Fe/Al bound P, and occluded P in biochar, while increased Ca bound P from 78 to 85% to 85–96%. Liquid 31P NMR indicated that exogenous Ca induced the crack of the P-O-P bond in pyrophosphate to become orthophosphates. It also explained why new orthophosphates including chlorapatite (Ca5(PO4)3Cl) and calcium hydroxyapatite (Ca10(PO4)6(OH)2) appeared in the Ca-composite biochar compared to pristine biochar. Combined with rapid P-release test in paddy soil (pH 6.27) and 30-days rice seedling growth test under flooded condition (10 wt% biochar addition ratio), it was confirmed that compared to pristine biochar, Ca-composite biochar released more P in paddy soil, but also promoted more P to be taken in by rice root and stalk. These results suggested that pretreating biowaste with Ca ion was a friendly approach to enhance P reclamation during biochar formation, making it a promising P fertilizer.

Oil and gas production from the pyrolytic transformation of recycled plastic waste: An integral study by polymer families

Different plastics recovered from a local urban solid waste plant were collected before landfilling, separated, and classified by families, i.e. polyethylene (PE), polypropylene (PP), high impact and expanded polystyrene (HIPS and EPS, respectively), polyethylene terephthalate (PET), and polyvinyl chloride (PVC). A systematic pyrolysis study was carried out to compare the different behavior registered in each plastic type, and an integral analysis of the produced oils and synthetic gas was conducted. In general terms, the oil yield followed the order EPS > PP > PE > HIPS > PET > PVC, reaching maximum values over 500 °C after 1 h of treatment. The oil from HIPS, EPS, PET, and PP was rich in light compounds, i.e., C5-C9 hydrocarbons. Almost 100 % of the oil from HIPS and EPS pyrolysis was aromatic. The aromatic fraction was important in the case of PVC (57 %) and PET (45 %). PE produced an oil with the most varied distribution of compounds but rich in olefins (67 %). The analysis of the non-condensable composition of the gas showed that in all the pyrolysis gases methane was over 50 % (vol.), followed by ethane in importance. CO was produced in the case of PET.

Recycling of biomass wastes from amarula husk by a modified facile economical water salt method for high energy density ultracapacitor application

In this study, we are reporting for the first time the activated carbon from amarula seed husk (AMH) produced by a modified facile synthesis method producing low-cost, high porosity materials through impregnation of raw materials with water salt. The water salt treatment resulted from the salt formed by a mixture of calcium chloride and phosphoric acid. Calcium influences the catalytic of dehydroxylation and desiccation while phosphate groups stimulates the pyrolytic transformation of the raw material which increases the expansion of pores on the surface of the carbon materials thus prevents destruction of the carbon structure and produce a high yield. The treated AMH with water salt displayed high specific surface area with a maximum specific capacitance of 275 F g−1 at 0.5 A g−1 in a three-electrode configuration. The fabricated symmetric device presented a specific energy and power of 16 Wh kg−1 and 450 W kg−1 at 0.5 A g−1, and retained 10 Wh kg−1 and 18 kW kg−1 at 20 A g−1. The symmetric device retained a capacitance retention of 94.3 % noted after 13,000 cycling and 88.5 % for up to 20,000 cycling at 5 A g−1. An exceptional increase in specific energy from 15.5 to 38.3 Wh kg−1 at 1 A g−1 was noted after 200 h floating time. The results propose the potential synthesis progress for recycling and transforming economical biomass waste for developing high performing energy storage device. The approach used in this work is simple and cost-efficient compared to other method that comprises of high temperature and organic chemicals, which are poisonous and corrosive to the environment.

Fullerphene Nanosheets: A Bottom‐Up 2D Material for Single‐Carbon‐Atom‐Level Molecular Discrimination (Adv. Mater. Interfaces 11/2022)

Fullerphene Nanosheets In article number 2102241, Jingwen Song, Jonathan P. Hill, Lok Kumar Shrestha, Katsuhiko Ariga, and co-workers describe the synthesis of large area ultrathin fullerphene nanosheets using a Pickering emulsion precursor to obtain homogeneous fullerene film. Pyrolytic transformation of the film yields fullerphene film used to establish selective sensing of acid analytes.

Engineering Catalytic Interfaces in Cuδ+/CeO2-TiO2 Photocatalysts for Synergistically Boosting CO2 Reduction to Ethylene.

Photocatalytic CO2 conversion into a high-value-added C2 product is a highly challenging task because of insufficient electron deliverability and sluggish C-C coupling kinetics. Engineering catalytic interfaces in photocatalysts provides a promising approach to manipulate photoinduced charge carriers and create multiple catalytic sites for boosting the generation of C2 product from CO2 reduction. Herein, a Cuδ+/CeO2-TiO2 photocatalyst that contains atomically dispersed Cuδ+ sites anchored on the CeO2-TiO2 heterostructures consisting of highly dispersed CeO2 nanoparticles on porous TiO2 is designedly constructed by the pyrolytic transformation of a Cu2+-Ce3+/MIL-125-NH2 precursor. In the designed photocatalyst, TiO2 acts as a light-harvesting material for generating electron-hole pairs that are efficiently separated by CeO2-TiO2 interfaces, and the Cu-Ce dual active sites synergistically facilitate the generation and dimerization of *CO intermediates, thus lowering the energy barrier of C-C coupling. As a consequence, the Cuδ+/CeO2-TiO2 photocatalyst exhibits a production rate of 4.51 μmol-1·gcat-1·h-1 and 73.9% selectivity in terms of electron utilization for CO2 to C2H4 conversion under simulated sunlight, with H2O as hydrogen source and hole scavenger. The photocatalytic mechanism is revealed by operando spectroscopic methods as well as theoretical calculations. This study displays the rational construction of heterogeneous photocatalysts for boosting CO2 conversion and emphasizes the synergistic effect of multiple active sites in enhancing the selectivity of C2 product.

Pitch oil production – An intangible cultural heritage in Central Europe

Pitch oil production from Scots pine (Pinus sylvestris L.) resinous wood is an intangible cultural heritage in the Central European region including the Czech Republic, Northern Austria and South Eastern Germany, and is related to traditions in Finland and Southern France. The heating of wood in small kilns also fueled by wood produces liquid for collection. Our detailed investigations of three pitch oil kilns in Upper Austria led to the discovery of relationships to the production of pine and birch tar in Fennoscandia and black pine tar production in Western Anatolia. Our measurements of temperatures at the bases of the kilns revealed a slow temperature rise. We predicted maximum temperatures based on infrared spectra, and measured overall temperatures in the range of 250 °C–650 °C. With gas chromatographic analyses of pitch oil we detected a dominant proportion of resin components and only a minor proportion of compounds attributable to pyrolytic transformation of solid wood mass. In most pitch oil samples the extractives comprised 90 %. Most samples were similar and only the first samples at the starting outflow were systematically dominated by pyrolysis products. Tar runoff from a traditional circular charcoal kiln for charcoal production – used as a reference – had a strongly different composition, with a high proportion of pyrolysis compounds.

Comparative study on pyrolytic transformation mechanism of ANFs-derived carbon membrane for electromagnetic interference shielding application

Selecting suitable precursor and exploring controllable carbonization process is crucial to carbon materials, especially for carbon-based material in electromagnetic interference shielding application. However, carbon materials are primarily used in the forms of powders, which remains big challenge in developing continuous ones. Herein, large-scale aramid nanofibers (ANFs)-derived carbon membrane was developed for the first time. Influence of pyrolysis temperature on chemical constitution and crystalline structure during carbonization process was investigated. The results showed that the decomposition stage of ANFs freestanding membrane begun at ~ 474 °C, while the reconstruction stage begun at ~ 600 °C. Besides, the rupture of amide bonds occurred around 500 °C, which was validated by disappearance of C=O groups. Moreover, the declining integrated intensities ID/IG, and the sharp rising electrical conductivity of demonstrated progressive aromatization and ring condensation. In addition, the microgrooves with an average diameter of ~ 40 nm were formed during the carbonization. Subsequently, the ANFs-derived carbon membrane exhibited superior conductivity (123.8 S cm−1) and electromagnetic shielding effectiveness value of 16 dB (X band) with thickness of 28 μm. This work provided feasible strategy in fabricating carbon-based membrane for advanced electronic devices.

Pyrolytic transformation behavior of hydrocarbons and heteroatom compounds of scrap tire volatiles

Pyrolysis has been a major method to dispose the problem of scrap tires and it is gaining enormous attention all over the world. But less is known about its comprehensive transformation behavior of pyrolysis products. Experiments on pyrolysis of scrap tires were carried out using Py-GC/MS to investigate the distribution of volatile products at five typical temperatures of 200, 300, 400, 500, and 800 °C. Products generated at each temperature stage were categorized according to their functional group for exploring the possible chemical formation pathways. It was found that pyrolysis products were distributed at all temperature stages and predominantly produced at 300–400 °C. Hydrocarbon volatiles were mainly composed of alkenes, especially sesquiterpenes, D-limonene and isoprene. Heteroatom volatile products were all generated below 500 °C. Fatty acids, alkenyl alcohols, sulfides, diphenylamine, nitriles, and benzothiazole were predominant heteroatom products identified in this study. Based on Py-GC/MS results, pyrolytic transformation behavior of hydrocarbons and heteroatom compounds was proposed. In addition, a deeper investigation into the evolution of sulfur was conducted since it was the leading contaminant during the overall pyrolysis process. Results showed that about 60.98 wt% of total sulfur was distributed in the solid residues and was mostly in the form of sulfides and thiophenes. Sulfur content in liquid and gas products was 29.52 wt%, and 7.64 wt%, respectively. Overall, the results of this research presented an in-depth pyrolysis regularity of scrap tire volatiles and provided theoretical guidance for directional valorization of pyrolytic oil.

Synthesis Based on a Preceramic Polymer and Alumina Nanoparticles via UV Lithography for High Temperature Applications.

Because of the increased demand for preceramic polymers in high-tech applications, there has been growing interest in the synthesis of preceramic polymers, including polysiloxanes and alumina. These polymers are preferred because of their low thermal expansion, conformability to surfaces over large areas, and flexibility. The primary objective was to evaluate the aspects of polymer-derived ceramic routs, focusing on the UV lithography process of preceramic polymers and the pyrolyzing properties of the final ceramics. We found that the p(DMS-co-AMS) copolymer was effective in scattering the hydrophilic Al2O3 nanoparticles into the exceedingly hydrophobic solvent. The physico-chemical behavior of characterized copolymers was explored during their pyrolytic transformation into amorphous silicon-based ceramics. The results indicate that an increase of the pyrolysis temperature degraded the Si–O network through the carbothermic reaction of silicon. We also found a rapid elimination of copolymer pores and densification when the temperature increased (1100 to 1200 °C). At different but specific temperature ranges, there are different distinct rearrangement reactions in the conversion of polymer to ceramic; reductions of the melting point (Tm) of the total heat of melting (ΔHm) of the pyrolysis process resulted in the crystallization of ceramic materials; hence, lithography based on pyrolysis properties of preceramic polymers is a critical method in the conversation of polymers.

Pyrolytic Transformation of Indigenous Biomass Wastes into Biochar: An Insight into Char Structure and Physicochemical Characteristics

Pyrolytic Transformation of Indigenous Biomass Wastes into Biochar: An Insight into Char Structure and Physicochemical Characteristics

Pyrolytic Transformation of Indigenous Biomass Wastes into Biochar: An Insight into Char Structure and Physicochemical Characteristics

Pyrolytic Transformation of Indigenous Biomass Wastes into Biochar: An Insight into Char Structure and Physicochemical Characteristics

Assessing thermal behaviours of cellulose and poly(methyl methacrylate) during co-pyrolysis based on an unified thermoanalytical study

The objective of this study was to evaluate pyrolysis and co-pyrolysis behavior of cellulose and poly(methyl methacrylate) (PMMA) and examine the kinetics of the processes by using thermogravimetric analysis (TGA) coupled with FT-IR spectrometry. For this purpose, non-isothermal experiments were carried out using different heating rates and three prominent iso-conversional methods were used to obtain kinetic parameters at various extents of conversions from 0.1 to 0.9. Blending PMMA with cellulose had a marked effect on the process. The results of co-pyrolysis using a blending ratio of 50 wt% PMMA indicated that the highest rate of pyrolytic transformation was achieved at a conversion degree of 0.5 while activation energy ranged from 188.1 to 364.3 kJ/mol. The most intensive gas release during cellulose pyrolysis was CO2. Co-pyrolysis was more complicated than that of pyrolysis of cellulose and PMMA due to depolymerization and radical interactions.

Effect of Pyrolysis Temperature on the Mechanical Response in Partially Pyrolysed Polysiloxanes

The pyrolysis process of polysiloxane resin conducted in the temperature range 400 – 700 °C results in hybrid materials owning some polymeric (thermosetting) behaviour. A certain level of elastic recovery and/or viscoelastic flow showed at various steps of pyrolytic transformation was monitored using the instrumented Vickers hardness method. Determined indentation force-indentation depth curves reflect the mechanical response and the level of the transformation; however, the relaxation behaviour is not covered by this method fully. An extensive indentation relaxation was revealed in the material partially pyrolysed at 400 °C, about 16 % and 8 % when the HV 0.1 and the HV 0.2 loading were applied, respectively. Materials pyrolysed from 500 to 650 °C which exhibited the indentation relaxation below 1 % and the mostly elastic response on the loading were observed. Above the pyrolysis temperature of 600 °C a rapid onset of mechanical properties, namely indentation elastic modulus and hardness, was observed. The short-term indentation relaxation was evaluated via the indentation force relaxation method in the regime of constant indentation depth obtained at the moment of reaching an initial force of 0.981 N or 1.962 N. The obtained indentation force relaxation curves were analysed on the basis of a logarithmic function. The significant effect of the pyrolysis temperature as well as the influence of loaded volume was described.

Metal–Organic Framework Mediated Cobalt/Nitrogen‐Doped Carbon Hybrids as Efficient and Chemoselective Catalysts for the Hydrogenation of Nitroarenes

AbstractA Co@N‐doped carbon (Co@NC) hybrid was synthesized by thermal decomposition of the metal–organic framework (MOF) ZIF‐67 under N2 atmosphere. These hybrid materials exhibit outstanding catalytic activity and chemoselectivity for the conversion of a wide range of substituted nitroarenes to their corresponding anilines under relatively mild reaction conditions. The high catalytic performance is attributed to the formation of cobalt nanoparticles and to the presence of atomically dispersed Co species in close interaction with nitrogen‐doped graphene. Both active species are formed in situ during the pyrolytic transformation of ZIF‐67. The catalysts could be reused in consecutive runs, exhibiting a slightly lower activity ascribed to blockage of the active sites by strongly adsorbed reaction species. These results open up a pathway for the design of noble‐metal‐free solid catalysts for industrial applications.

Amphiphilic Graft Copolymers as a Versatile Binder for Various Electrodes of High-Performance Lithium-Ion Batteries.

It is known that grafting one polymer onto another polymer backbone is a powerful strategy capable of combining dual benefits from each parent polymer. Thus amphiphilic graft copolymer precursors (poly(vinylidene difluoride)-graft-poly(tert-butylacrylate) (PVDF-g-PtBA)) have been developed via atom transfer radical polymerization, and demonstrated its outstanding properties as a promising binder for high-performance lithium-ion battery (LIB) by using in situ pyrolytic transformation of PtBA to poly(acrylic acid) segments. In addition to its superior mechanical properties and accommodation capability of volume expansion, the Si anode with PVDF-g-PtBA exhibits the excellent charge and discharge capacities of 2672 and 2958 mAh g(-1) with the capacity retention of 84% after 50 cycles. More meaningfully, the graft copolymer binder shows good operating characteristics in both LiN0.5 M1.5 O4 cathode and neural graphite anode, respectively. By containing such diverse features, a graft copolymer-loaded LiN0.5 M1.5 O4 /Si-NG full cell has been successfully achieved, which delivers energy density as high as 546 Wh kg(-1) with cycle retention of ≈70% after 50 cycles (1 C). For the first time, this work sheds new light on the unique nature of the graft copolymer binders in LIB application, which will provide a practical solution for volume expansion and low efficiency problems, leading to a high-energy-density lithium-ion chemistry.

Metal-Polysaccharide Interplay: Beyond Metal Immobilization, Graphenization-Induced-Anisotropic Growth.

Such sweet support: Metal-polysaccharide interplay affords, after pyrolytic transformation, highly active catalysts based on anisotropically oriented nanoparticles supported on graphene sheets.

Properties of single-phase gallium nitride (GaN) films formed using a Ga(S2CN(CH3)2)3 nanoparticle solution

Ga(S2CN(CH3)2)3 (Ga(DmDTC)3) nanoparticles (diameter: ∼28.5 nm) were synthesized using an ultrasonic spray method, and Ga(DmDTC)3 films were deposited using a spin coating technique. The GaN films were formed by the pyrolytic transformation of Ga(DmDTC)3 films under a NH3 atmosphere at 850 °C for 10 min. The as-formed GaN films exhibited a hexagonal Wurtzite structure with a (0002) preferred orientation and showed strong photoluminescence centered at 2.95 eV. The Ga to N elemental ratio was 1:0.9 with sulfur detected in small amounts in the XPS spectrum. This result showed that almost all of the sulfur atoms in the Ga2S3 were replaced with nitrogen atoms, and the remaining sulfur atoms formed sulfur-doped GaN (GaN:S) under the NH3 environment. Furthermore, epitaxial GaN films on the pyrolytic GaN films, which were formed by MOCVD, exhibited lateral growth, whereas the GaN films on bare sapphire substrates were grown upward toward the z-axial direction. The developed method in this study is a simple technique to form single-phase GaN films using a liquid precursor and can be useful as a semi-homo substrate for GaN epitaxial growth.

N-doped polymer-derived Si(N)OC: The role of the N-containing precursor

Abstract