Pyrolysis Method Research Articles

High loading and sustained-release system of doxorubicin-carbon dots as nanocarriers for cancer therapeutics

Nanocarriers for drugs have been investigated for decades, yet it is still challenging to achieve sustained release from nanomaterials due to drug loading inefficiency and burst release. In this study, we developed novel functional carbon dots (CDs) and investigated the therapeutic efficacy by studying the loading efficiency and release behavior of the anticancer drug doxorubicin (DOX). CDs were successfully synthesized using a one-step pyrolysis method with varying concentrations of citric acid (CA) and thiourea (TU). Functional groups, morphology, particle size, and zeta potential of synthesized CT-CDs and DOX loaded CT-CDs were investigated by UV-visible, Fluorescence, dynamic light scattering, Zeta Potential measurements, FTIR, and transmission electron microscopy. The zeta potential data revealed DOX loading onto CT-CDs by charge difference, i.e. -24.6 ± 0.44 mV (CT-CDs) and 20.57 ± 0.55 mV (DOX-CT-CDs). DOX was loaded on CDs with a loading efficiency of 88.67 ± 0.36%.In vitrodrug release studies confirmed pH-dependent biphasic drug release, with an initial burst effect and sustained release of DOX was found to be 21.42 ± 0.28% (pH 5), 13.30 ± 0.03% (pH 7.4), and 13.95 ± 0.18% (pH 9) even after 144 h at 37 °C. The CT-CDs were non-toxic and biocompatible with L929 Fibroblasts cells. The cytotoxic effect of DOX-CT-CDs showed a concentration-dependent effect after 48 h with Glioblastoma U251 cells. Flow cytometry was used to examine the cellular uptake of CT-CDs and DOX-CT-CDs in L929 and U251 cells. It was observed that the maximum CT-CDs uptake was around 75% at the end of 24 h. This study showed that the synthesized fluorescent CT-CDs demonstrated a high drug loading capacity, pH-dependent sustained release of DOX, and high cellular uptake by mammalian cells. We believe this work provides practical and biocompatible CDs for chemotherapeutic drug delivery that can be applied to other drugs for certain therapeutic aims.

Waste to Energy; Conversion of Plastic Waste into Liquid Fuel Equivalent to Diesel and Gasoline Using the Pyrolysis Method

Abstract The aim of this research is to produce oil equivalent to diesel and gasoline from plastic waste using the pyrolysis method, examining its physico-chemical properties and comparing it with conventional diesel and gasoline. The production of diesel oil and gasoline from plastic waste is a topic that has received increasing attention in recent years, due to increasing awareness of the environmental problems caused by plastic waste and the need for alternative energy sources. Methods for converting plastic waste into liquid fuel, separating diesel and gasoline equivalents and examining their physico-chemical properties are the main focus of this research. Pyrolysis is the process chosen because the technology is simpler than other methods, such as gasification for example. A total of 6000 grams of plastic chips were pyrolyzed in an LPG-fueled reactor. Pyrolysis was carried out at temperatures of 200, 250, 300, 350, 400 °C, then the yield of oil produced at each temperature was weighed. It was found that the optimum temperature for pyrolysis was 300 because the increase in yield afterwards was very small. Next, 2000 grams of pyrolysis oil was distilled by gradually increasing the temperature from 100 to 300. The resulting 1520 grams or 79.17% gasoline equivalent fraction, 320 grams or 16.67% diesel fraction, the remaining 80 grams or 4.17% residual oil. The results of the physico-chemical properties examination showed that the diesel and gasoline fractions were similar to conventional diesel and gasoline.

Effects of different low-temperature pyrolysis treatments on the biotoxicity of biochar derived from tobacco stalks

The pyrolytic treatment of tobacco stalk (TS) waste results in the production of a large amount of biochar, which is usually used for environmental remediation. However, little attention has been given to the effects of different pyrolysis methods on the biotoxicity of TS biochar. This study examined the effects of three different pyrolysis methods at 350 °C (fast pyrolysis, slow pyrolysis, and low-temperature carbonization) on the biotoxicity of TS biochar (Escherichia coli (E. coli) growth and wheat germination). The results revealed that the dissolved organic matter (DOM) of the three types of biochar promoted the growth of E. coli, and the maximum growth of E. coli was ranked as DOM-F350 > DOM-S350 > DOM-350. However, the DOM inhibited the growth of the wheat seeds, with the growth index (below 0.8) of the wheat seeds ranked as DOM-350 > DOM-F350 > DOM-S350. The alkali metal content, pH and humus-like substance content of biochar may be responsible for the biotoxicity of biochar through various mechanisms. In addition, TS-S350 exhibited greater biotoxicity than did TS-F350 because of the greater content of toxic nitrogen-containing organic compounds. These findings can provide reliable theoretical guidance for the effective management and safe utilization of TS waste.

Mechanical properties and microstructure of quartz fiber-reinforced silica matrix composite with a single layer pyrocarbon interphase

Silica matrix composites (SiO2f/SiO2), reinforced with pyrolytic carbon (PyC) interfacial layers, were synthesized using the precursor impregnation and pyrolysis (PIP) method, mechanical properties and microstructure of these composites were thoroughly investigated. The flexural strength of SiO2f/PyC/SiO2 composites exceeded 55 MPa after treatment at 450°C. Notably, at medium and high temperatures, strength of SiO2f/SiO2 composites was significantly enhanced compared to that of uncoated PyC composites. The experimental resulted indicate that PyC temporary interfacial layer effectively mitigated the strong interfacial reaction between quartz fibers and matrix. Furthermore, fiber pull-out phenomenon observed at the fracture of SiO2f/PyC/SiO2 composites suggested that interfacial bonding was weak, which contributed to the high mechanical strength of these composites.

Mechanism and kinetic study of n-undecane degradation on Co-CeO2: A dual approach combining thermal and plasma catalysis

The catalytic degradation of long-chain alkanes presents a formidable challenge in environmental chemistry. n-Undecane (C11), a quintessential long-chain alkane, predominates as a component of volatile organic compounds (VOCs) emitted from the printing industry and diesel-powered vehicles. The uncontrolled release of these compounds into the atmosphere necessitates stringent measures. This study reports on the plasma-catalytic degradation of n-undecane over the CeO2 based catalysts cooperated with cobalt (Co), manganese (Mn), aluminum (Al), nickel (Ni), iron (Fe), or magnesium (Mg) via aerosol pyrolysis method. Notably, the Co-doped CeO2 catalyst with a Co:Ce atom ratio of 4:1, in conjunction with plasma, achieves an optimal degradation performance. Under the reaction conditions of 90 °C and an energy density of 40 J/L, C11 conversion and COx selectivity reached impressive levels of 100 % and 97 %, respectively. Characterization findings indicate that elevated ratios of Ce3+/(Ce3++Ce4+) and Co3+/(Co2++Co3+) are conducive to the catalytic degradation of C11. Kinetic models have been developed to elucidate the thermal and plasma catalytic degradation mechanisms

Honeycomb-like porous carbons derived from multistep pyrolysis of artificial humic acids as efficient sorbents for removing diethyl phthalate

The uprecycling of hydrothermal liquid waste-derived artificial humic acids into stable carbon materials is helpful for advancing the development of hydrothermal carbonization technology, but it has rarely been investigated. For the first time, a multistep pyrolysis method was designed to convert artificial humic acids into honeycomb-like porous carbons (PCs). The obtained PCs exhibited a high specific surface area, reaching 1728.55 m2/g, while nonactivation treatment still provided a high value of 1425.14 m2/g. The high-pyrolysis process yielded graphite-like structures and maintained surface functional groups. PCs have been applied as sorbents to remove the emerging plasticizer diethyl phthalate (DEP) in water environments and exhibit promising sorption capabilities (as high as 993.30 mg/g), which are much higher than those reported for other sorbents. The sorption rate was controlled by mass transfer and chemical-like sorption, whereas the sorption capability was controlled mainly by the adsorption process, especially pore filling. Partitioning, hydrogen bonding, pore filling and π–π stacking are possible sorption mechanisms. In addition to the specific surface area, the pore volume is a suitable parameter for assessing the sorption capability. Exogenous dissolved organic matter can affect the sorption of DEP onto PCs through cosorption and coverage of their surface, but its influence is limited. Excellent sorption performance can cover a wide range of pH conditions. The prepared PCs also showed notable reusability and practicality. In this study, an excellent method was proposed for recycling hydrothermal liquid waste and preparing PCs, and the prepared PCs exhibited great potential for environmental remediation.

Hollow carbon nanofibers with self-induced internal electric field for high-performance full-carbon sodium ion capacitors

Self-induced internal electric field (SIEF) is crucial to achieve high capacity, high rate and long cycle life of carbon anodes in Na+ storage, but it is also a huge challenge currently. Herein, a template-assisted electrospinning process and subsequent low-temperature pyrolysis method is employed to synthesize S, N co-doped hollow carbon nanofibers (SNHCF) with rich micropores and chemisorption sites. The rich micropores and interconnected macroporous in SNHCF provide large internal availability that effectively exposing the active sites, inhibiting the volume expansion and shortening the Na+ diffusion distance. Besides, S, N co-doping in the carbon skeleton can act as an electron acceptor and electron donor respectively to form a SIEF to boost adsorption of Na+. Theoretical calculation and ex-situ characterizations confirmed that S, N co-doping can regulate the electronic configuration and reduce the diffusion barrier of Na+. As a result, SNHCF anode has ultra-high specific capacity (588.2mAh g−1 at 0.05 A/g) and impressive rate performance (264.3mAh g−1 at 20 A/g). The full-carbon sodium ion capacitors assembled with SNHCF anode and activated carbon cathode exhibits high energy density (119 Wh kg−1) and ultra-long cycle stability (80.06 % capacity retention after 12,000 cycles).

Improved demineralization of the carbon black obtained from the pyrolysis of the sidewall and tread of scrap Tires: Extraction of some micro-/macro-nutrient elements of plants

In parallel with the increasing tyre production in the world, the amount of scrap tyres is also increasing. Within the scope of scrap tyre management, studies aimed at preventing the accumulation of tyres that threaten the world in terms of human health and the environment can be briefly defined as 4RL, including recycling, reuse, recovery, regeneration, landfill. Current methods have not yet completely controlled the accumulation of scrap tires. In this study, sidewall and tread parts of scrap tires with different compositions were pyrolyzed separately. Pyrolytic carbon black has been upgraded with an improved acid-base extraction method. Two different carbon blacks of high commercial value were obtained from the tire sidewall and tread. Since the mixture obtained from acidic-basic extraction, consisting of elements such as Zn, K, Na, Ca and S, are micro and macro nutrients of plants, the solution can be used directly in the fertilizer industry. With this study, the commercial value of solid residue, which is a major bottleneck in tire pyrolysis plants, has been increased. The pyrolysis method has been transformed into a more feasible project.

Development of the Diffusive Gradient in Thin Film (DGT) Method with CaO/Biochar Binding Agent from Eggshells and Rice Straw Waste for Determining the Concentration of Phosphate

Phosphorus, often found in the form of phosphate in the environment, especially aquatic environments, has been identified as the primary contaminant that causes algae blooms and eutrophication. Phosphate adsorption in the aquatic environment was carried out by comparing the adsorption capabilities of eggshell (CaO), rice straw (BC) and CaO/biochar materials at mass variations of 1:1, 1:2 and 2:1 from the use of eggshell and rice straw waste. Each material was synthesized using ball milling and pyrolysis methods. The adsorption isotherm and kinetics of the material are by the Langmuir adsorption isotherm and are pseudo-second-order (PSO) adsorption kinetics. The CaO/biochar 1:2 material shows the highest phosphate adsorption capacity at pH 12 with a contact time of 24 hours. CaO/biochar 1:2 was applied in the phosphate adsorption process using the Diffusive Gradient in Thin Film method as a binding agent, which acts as an adsorbent. The DGT technique is an in situ sample preparation technique for identifying the presence of phosphate, a labile species. The binding agent material was characterized using FTIR, XRD, and BJH-BET instruments. The success of synthesizing CaO/biochar 1:2 binding gel and ferrihydrite was demonstrated by the appearance of the same adsorption as the diffusive gel using FTIR. The CaO/biochar binding gel demonstrated that it is a better material compared to the ferrihydrite binding gel for phosphate adsorption, achieving CDGT values of 10.1727 mg/L and 2.5959 mg/L at pH 5 and 3, respectively, with a phosphate concentration of 10 mg/L. These findings underscore the potential of CaO/biochar as a more effective material for phosphate removal applications.

The antibacterial efficacy of reduced graphene oxide (rGO) and rGO/ZnO composites produced through thermal pyrolysis method against various bacterial strains

The antibacterial efficacy of reduced graphene oxide (rGO) and rGO/ZnO composites produced through thermal pyrolysis method against various bacterial strains

Peroxymonosulfate Activation by Fe@N Co-Doped Biochar for the Degradation of Sulfamethoxazole: The Key Role of Pyrrolic N

In this study, Fe, N co-doped biochar (Fe@N co-doped BC) was synthesized by the carbonization–pyrolysis method and used as a carbocatalyst to activate peroxymonosulfate (PMS) for sulfamethoxazole (SMX) removal. In the Fe@N co-doped BC/PMS system, the degradation efficiency of SMX (10.0 mg·L−1) was 90.2% within 40 min under optimal conditions. Radical quenching experiments and electron spin resonance (ESR) analysis suggested that sulfate radicals (SO4•−), hydroxyl radicals (•OH), and singlet oxygen (1O2) participated in the degradation process. After the reaction, the proportion of pyrrolic N decreased from 57.9% to 27.1%. Pyrrolic N served as an active site to break the inert carbon network structure and promote the generation of reactive oxygen species (ROS). In addition, pyrrolic N showed a stronger interaction with PMS and significantly reduced the activation energy required for the reaction (∆G = 23.54 kcal/mol). The utilization potentiality of Fe@N co-doped BC was systematically evaluated in terms of its reusability and selectivity to organics. Finally, the intermediates of SMX were also detected.

Synthesis of Titanium-Based Powders from Titanium Oxy-Sulfate Using Ultrasonic Spray Pyrolysis Method.

Submicron and nanosized powders have gained significant attention in recent decades due to their broad applicability in various fields. This work focuses on ultrasonic spray pyrolysis, an efficient and flexible method that employs an aerosol process to synthesize titanium-based nanoparticles by transforming titanium oxy-sulfate. Various parameters are monitored to better optimize the process and obtain better results. Taking that into account, the influence of temperature on the transformation of titanium oxy-sulfate was monitored between 700 and 1000 °C. In addition to the temperature, the concentration of the starting solution was also changed, and the flow of hydrogen and argon was studied. The obtained titanium-based powders had spherical morphology with different particle sizes, from nanometer to submicron, depending on the influence of reaction parameters. The control of the oxygen content during synthesis is significant in determining the structure of the final powder.

Lunar in-situ ironmaking through laser-assisted flash vacuum pyrolysis of iron oxide

The in-situ metallurgy of lunar regolith minerals for extracting metals and oxygen is a promising approach for the future construction of lunar bases. In this study, a novel laser-assisted flash vacuum pyrolysis (LFVP) method was proposed and developed for the production of metallic iron and oxygen from lunar regolith using iron oxide as raw material. First, the theoretical feasibility of vacuum pyrolysis of FeO was conducted through thermodynamic calculations. Subsequently, an experiment on laser heating of iron oxides was performed, with a reduction rate of FeO of approximately 15.5 % (±0.6 %). Scanning electron microscopy and transmission electron microscopy images revealed that the micronano-level metallic iron exhibited spherical particles, strip-like and irregularly shaped aggregates. The spatial distribution unevenness of the formed metallic Fe, differences in the condensation conditions of gaseous products, and the surface tension effects of liquid metallic iron were mainly attributed to the disparities in the morphology of metallic iron. Meanwhile, the process mechanism of vacuum pyrolysis of FeO was also analyzed. Therefore, LFVP of FeO for producing metallic iron represents a novel ironmaking technology, offering a promising solution for extracting metals and oxygen in situ from lunar minerals for future lunar base construction.

RECYCLING OF PLASTIC WASTE BY THE PYROLYSIS METHOD

Chemical recycling of plastic waste can be a useful complement to mechanical recycling to achieve the required rate of plastics recycling and create a climate-neutral and resource-saving circular economy. Various mixed plastic wastes to be recycled in the future are investigated under fully uniform intermediate pyrolysis conditions characterized by moderate heating rates and pyrolysis temperatures. The distribution of the product and the selected properties of the product are determined, and the mass and energy balance of the process is obtained. Product yield and composition are highly dependent on pyrolyzed residues. All results indicate that pyrolysis is a suitable process for obtaining chemical feedstocks from various complex mixed plastic wastes. The main mass and energy balances for chemical recycling of mixed plastic waste by pyrolysis method were determined. Products for recycling raw materials can be obtained from all investigated plastic waste. Product quality often depends on raw materials. The energy requirement for heating, melting, pyrolysis and evaporation is about 5% of the calorific value of the raw material. It has been demonstrated that 50 to 75% of the raw carbon can be recovered in the condensate and reintroduced into the value chain in the chemical industry.

A high-capacity and stable dual-ion battery based on an ultra-large lattice-spacing amorphous carbon anode

Compared with traditional lithium-ion batteries (LIBs), dual-ion batteries (DIBs) offer advantages such as high operating voltage, good safety performance, and low cost. However, DIBs often suffer from challenges such as low specific capacity and poor cycling performance in practical applications. Here, a layered nitrogen-doped carbon anode has been prepared using a one-step pyrolysis method with excellent Li+ storage sites. The large lattice spacing of 0.55 nm provides more space for the storage and migration of active ions. Concurrently, the utilization of concentrated electrolyte facilitated the electrochemical window and the restrained solvation of ions, which helps to boost ion transport and improve the stability of the electrolyte and the operating voltage of DIBs. The assembled DIBs exhibit a high specific discharge capacity of 179.27 mA h g−1, within a 2.5–4.8 V voltage range, and excellent cycling stability of 3500 cycles without degradation. Specifically, the structural evolution of the electrodes during charging and discharging and the working mechanism of the DIBs are also explored. The DIBs system designed in this paper provides a facile and scalable approach to promote the development of DIBs with low-cost and high-performance.

Spray pyrolysis grown Cu and Ni co-doped ZnO thin films: a study of their structural, optical, wettability, and photocatalytic performance

This study explores the impact of Cu and Ni doping on the structural, wettability, optical, and photocatalytic properties of ZnO thin films. The co-doped thin films, with varying Ni concentrations, were deposited using a spray pyrolysis method onto pre-heated soda lime glass substrates. X-ray diffraction analysis confirmed the hexagonal wurtzite structure with preferred orientation primarily along the (002) plane, while crystallinity decreased with higher Ni concentrations. Scanning electron microscopy reveals a compact, adherent structure in all films, with Ni incorporation altering the surface morphology. Fourier transform infrared spectroscopy identified characteristic absorption bands for metal-oxygen bonds. Optical analysis indicated that all thin films exhibited over 88% average transmittance in the visible region, accompanied by a red shift in the optical bandgap. Photoluminescence spectra exhibited a broad emission band in the visible region, indicating intrinsic and extrinsic defects induced by doping. Co-doping transforms the wettability character of ZnO thin films from hydrophilic to hydrophobic. Finally, the photodegradation efficiency of the thin films against methylene blue under sunlight significantly increases from 72% to 92% with an increase in Ni concentration.

Monolithic Nitrogen-Doped Carbon Electrode with Hierarchical Porous Structure for Efficient Electrochemical CO2 Reduction.

N-doped carbon materials have garnered extensive development in electrochemical CO2 reduction due to their abundant sources, high structural plasticity, and excellent catalytic performance. However, the use of powder carbon materials for electrocatalytic reactions limits their current density and mechanical strength, which pose challenges for industrial applications. In this study, we synthesized a monolithic N-doped carbon electrode with high mechanical strength for efficient electrochemical reduction of CO2 to CO through a simple pyrolysis method, using phenolic resin as the precursor and ZIF-8 as the sacrificial template. At 900 °C, the decomposition of ZIF-8 and the volatilization of Zn atoms promote the formation of a hierarchical porous structure in the carbon matrix, characterized by macropores with extended mesoporous channels. Simultaneously, N active species derived from ZIF-8 are effectively generated around the pores and fully exposed. The efficient mass transfer facilitated by the hierarchical porous structure and high activity of exposed nitrogen species enables efficient conversion of CO2 to CO. When the ZIF-8 content is 30%, the catalyst achieves a Faradaic efficiency of 88.9% for CO at a low potential of -0.7 V (vs RHE), with a CO production rate of 244.05 μmol h-1 cm-2. After 50 h of potentiostatic electrolysis, the current density and FECO remain stable. This work not only provides a strategy for the synergistic effects of hierarchical porous structures and nitrogen doping but also offers an effective method to avoid using powder binders and prepare integrated, stable monolithic electrodes.

Fabrication of temperature-regulated sorbitol/mannitol-doped copper oxides derived from a Cu complex and their photocatalytic properties

In this study, a series of composites containing copper oxide (CuxO) particles doped with sorbitol/mannitol, namely Cu/CuxO@C (x = 1 or 2), was successfully derived from a novel copper complex ([Cu(IPZ)2Cl2] (Cu-Complex), where IPZ = 4-Iodopyrazole) by pyrolysis method and exploiting the stability and modulation of the coordination sites of sorbitol/mannitol, which exhibited excellent photocatalytic properties. The results showed that Cu/CuxO@C possessed high efficiency in degrading rhodamine B (RhB), gentian violet (GV), methyl orange (MO) and Congo red (CR) dyes under UV irradiation, and the degradation effect was gradually enhanced with the increase of calcination temperature. The structural and chemical states of the materials were characterised in detail. Furthermore, the effects of experimental factors such as catalyst dose, solution pH, and inorganic anions on dye degradation efficiency were investigated. The photocatalytic mechanism study demonstrated that the primary oxygen-active substance was superoxide radical (·O2-). The electron transport hypothesis explains the effective separation of electrons and holes within a substance. The Cu/CuxO@C composite was regarded as a potential photocatalyst for dye wastewater treatment due to its high photocatalytic efficiency, reusability, and universality, offering a novel solution to environmental and energy issues.

Hydrogen bond-induced supramolecular self-assembly strategy to fabricate ultra-dispersed Cu-loaded porous tubular graphitic carbon nitride with rich nitrogen vacancies and CuNx sites for efficient photo-Fenton catalysis

The low utilization of visible light and easy recombination of charge carriers of graphitic carbon nitride (CN) restrain its application as photo-electron donor and metal site support in photo-Fenton system. Herein, a hydrogen bond-induced supramolecular self-assembly strategy was created to fabricate an ultra-dispersed Cu-loaded porous tubular CN composite (CA-Cu/TCN) by the hydrothermal–pyrolysis method with citric acid (CA) as initiator and chelating agent. CA-Cu/TCN with rich nitrogen vacancies (NVs) and abundant ultra-dispersed CuNx sites exhibited narrow bandgap, favorable visible light absorption capability, and high separation and transfer efficiency of charge carriers. CA-Cu/TCN effectively catalyzed the activation of H2O2 for generating abundant reactive oxygen species under visible light irradiation, contributing to efficient degradation of ciprofloxacin (CIP) with removal rate of 95.9 % and kinetic rate constant of 0.0948 min−1. The superior catalytic activity of CA-Cu/TCN can be ascribed to the effective transport of photogenerated electrons, high specific surface area, atomically dispersed Cu species, and enriched surface NVs. The mechanism of photo-Fenton catalytic degradation of CIP and possible degradation pathways were proposed as the dominant role of 1O2. Toxicity evaluation of CIP and intermediates indicated that the degradation of CIP was a gradual detoxification process. This work offers a novel self-assembly strategy to design and synthesize highly active and sustainable visible light-driven photo-Fenton catalysts for effectively degrading organic pollutants.

Synthesis and application of biomass-based graphene oxide using microwave-assisted pyrolysis method

Graphene and related materials have excellent potential to revolutionise many emerging fields, but the large quantity synthesis using environmentally sustainable methods is still challenging. This work studies the synthesis of graphene oxide from food waste biochar with negatively charged properties, which is initially produced using microwave pyrolysis. The synthesised graphene oxide achieved 64.53 % carbon content, 345.79 m2/g surface area, 0.074 cm3/g micropore volume, large reactive surface area, and ribbon/banded organisation. The performance of carbon-based material is evaluated in the fabrication of a modified screen-printed carbon electrode (SPCE) for selective dopamine (DA) detection in the coexistence of ascorbic acid (AA) and uric acid (UA). The electrostatic interactions between the negatively charged biochar-based graphene oxide (BBGO) on the surface SPCE and opposite-charged dopamine assisted the oxidation potential with interfering species by electrostatic repulsion of AA and UA. This manuscript substantiates the resource recovery from organic materials and sustainable graphene oxide synthesis, underscoring their application in detecting positively charged species.